PROSTHODONTICS-George A. Zarb, Charles L. Bolender et al.-Prosthodontic Treatment for Edentulous Patients_ Complete Dentures and Implant-Supported Prostheses-Mosby (2003)

494 Part Four Implant Prosthodontics

AB

Figure 26-5 Soft tissue penetration (A) and bone tissue–anchored portion (B) of a
postmortem preparation of a threaded implant design with excellent clinical documentation.
There are no adverse reactions to the implant seen in the soft or hard tissue.

changes may be exemplified by surface topograph- moderately rough implants developed the best bone
ical alterations. Qualitative changes refer to new fixation as described by peak removal torque and
potentially bioactive surfaces best exemplified by bone-to-implant contact (Wennerberg, 1996).
oxidized implants or surfaces doped with poten- “Moderately rough” surfaces were produced by
tially active substances. Today, new clinical blasting to an average height deviation (roughness
implants are marketed that are either quantitatively parameter Sa) of 1.5 μm, an average distance
or qualitatively surface altered or that are even a between the individual irregularities of 11.1 μm
combination of the two. (Sex) and a developed surface area ratio of 1.5 μm
(Sdr) (Figure 26-6), and were positively compared
Surface roughness is an implant-related property with smoother (turned and blasted) as well as
that has been used extensively in marketing diverse rougher-blasted implant surfaces. Very smooth sur-
oral implant systems. Because different machining faces (Sa values below 0.2 μm), which are in fact
processes result in different surface topographies, only used experimentally for abutment and anchor-
several implant manufacturers have machined age studies, will often be surrounded by a soft tis-
implants with a turning or milling process, which is sue interface indicative of imminent failure. The
a production method that has been the gold standard reasons as to why rough surfaces (Sa values around
for many years. and above 2.0 μm) demonstrate less firm bone fix-
ation when compared with less rough surfaces still
In a series of experimental studies performed in
rabbits, as well as in a few human experiments,

Chapter 26 The Science of Osseointegration 495

75 μm blasted, amd interferometry can be recommended for
flank threaded implants at this time.

Figure 26-6 A blasted surface with a roughness In recent experiments researchers have investi-
corresponding to the experimental ideal of 1.5 μm. gated the possibility of doping surfaces with differ-
ent kinds of bone-stimulating factors. Such
need to be investigated (Figure 26-7). The concerns dopings can be done with implants of any surface
with any surface roughening involve an increased roughness. A number of these bone-stimulating
risk of corrosion. However, current knowledge factors, growth factors, are present in our bodies
about such increased corrosion appears to be only and serve as important stimuli for the initiation of
a theoretical and not a practical problem. healing processes. However, external administra-
tion of growth factors may not necessarily improve
In this context it is worth emphasizing that a the healing situation. We have doped implants with
careful topographical characterization is essential bone morphogenetic proteins (BMPs) and other
for a reliable interpretation of the role of implant sur- growth factors and found no influence on the bone
face roughness for bone incorporation (Wennerberg response (Franke Stenport, 2002). One possible
and Albrektsson, 2000). There is a need for equip- explanation of this lack of a positive influence of
ment that can be used to measure arbitrary designs growth factors may be the fact that we only tried
and different surfaces. For example, only some them on regularly placed implants (i.e., a kind of
optical instruments such as confocal profilometry press fit healing situation). However, one cannot
exclude a positive influence of external administra-
Summary of thesis tion of growth factors in gap healing cases, such as
a tooth socket.
Bone tissue response
A rapidly growing number of publications
Roughness underscore the clinical popularity of certain oxi-
dized implants, and these implants may show
0.5 1.1 1.5 2.0 2.5 (Sa) strong bone responses quite independently of their
surface roughness (Sul, 2002). However, other
Figure 26-7 Experimentally the strongest bone types of oxidized implants depend mainly on their
response has a surface roughness of about 1.5 μm (Sa). surface roughness (Sul, 2002). In fact, oxidized
implants are manufactured in galvanic element
setups (thus the term anodized), and the used
electrolyte will influence subsequent tissue res-
ponses. The clinical use of oxidized oral implants
started some 10 years ago, but long-term out-
come data are still lacking (for review see Sul,
2002).

In essence, it is still unknown how much bone
contact is needed for an implant to be successful.
Consequently, the clinical relevance of different
surface (roughened and/or anodized) implants
can only be verified in controlled clinical studies.
However promising these surface alterations are,
to date, there is in most cases a lack of support-
ive data from such studies to verify any clinical
superiority of them. In fact, so far, only one sur-
face roughened system has been positively docu-
mented in controlled, randomized clinical studies
(Gotfredsen and Karlsson, 2001; Engquist et al.
2002).

496 Part Four Implant Prosthodontics

Implant Bed ately before irradiation will show a high failure
rate.
A healthy implant host site is required. Patient
characteristics, such as age, and history of the pro- Surgical Technique
posed host site(s), such as previous irradiation, will
affect the outcome of the implantation procedure. It Minimal tissue violence at surgery is essential for
also is believed that a history of smoking may proper osseointegration. This objective depends on
affect the healing response in osseointegration. continuous and careful cooling while surgical
drilling is performed at low rotatory rates, with sharp
Old age per se does not cause poorer implant instruments and the use of a graded series of drills.
results. However, extreme young age is a relative Proper drill geometry is important, as is intermittent
contraindication to the insertion of implants. The drilling, if the bone is of a very dense structure.
general recommendation is to await completion of The insertion torque should be of a moderate level
growth before inserting oral implants in young because strong insertion torques may result in stress
individuals. In selected cases, where strong psy- concentrations around the threads of a screw-type
chological motivation is present, oral implants may implant, with subsequent bone resorption.
be inserted in children, but then preferably only in
the anterior part of the jaw and in combination with Recent publications suggest the need to expand
overdenture therapy. In selected patients, bone- the surgical parameter to also include surgical skill.
anchored hearing aids may even be attached to It has been noted that individual surgeons’ success
implants when the child is only 2 or 3 years old. records may vary in both oral and orthopedic
The motivation behind treating such young chil- implant placement. Furthermore, at least two surgi-
dren is to avoid the potential social handicap of cal reports on outcomes in poor bone quality reveal
severe hearing impairment that cannot be treated in that technical excellence combined with a modi-
any other way. In the case of facial deformities, inser- fied surgical technique will yield predictably favor-
tion of skin-penetrating, bone-anchored implants able long-term outcomes. Both authors of these
usually is delayed until the child has reached puberty. reports used machine-turned implants, which were
therefore neither surface roughened or oxidized
Smoking has been reported to yield signifi- (Albrektsson, 2001)
cantly lower success rates with oral implants. The
mechanism behind this lowered success is unknown, Loading Conditions
but vasoconstriction may play a role. Continuing
substance abuse also may be a contraindication for The original recommendation to achieve osseointe-
implant treatment. gration is still valid: a two-stage implant insertion.
The implant is first inserted in the bone, and then
Previous irradiation is a relative contraindica- the soft tissues are sutured back so that the implant
tion for implant treatment (Jacobsson, 1985). After will be incorporated in bone under protected con-
implant therapy is decided, patients treated with ditions. At a second surgical procedure (minimally
irradiation should be transferred to special clinics 3 to 6 months later), the buried implant is exposed
with sufficient experience with such patients. A and connected to the oral cavity by means of a
1-year delay after irradiation before inserting transepithelial abutment. This procedure guaran-
implants is recommended. Expected success rates tees that the implant is well protected during its
are about 10% lower than for nonirradiated incorporation in bone when the osseous interface
patients. Hyperbaric oxygen treatment in divers’ has not been established properly, as evidenced
chambers has been shown to improve the outcome from experimental and clinical studies. Clinical tri-
in at least one published 5-year clinical follow-up als with various implant systems have now con-
study. If, on the other hand, patients have implants firmed the possibility of immediate functional
already in situ and osseointegrated when the need (direct) loading protocols, particularly in the
arises for therapeutic irradiation, removal of the mandible between the mental foramina. However,
implants before irradiation is not recommended. great caution is recommended with such an imme-
There is experimental evidence that osseointegrated
oral implants will remain stable in bone despite irra-
diation, whereas implants that are inserted immedi-

Chapter 26 The Science of Osseointegration 497

diate loading protocol in the maxilla, particularly if mental message in clinical epidemiology is that
the bone is judged to be of a poor quality. efficacy without effectiveness usurps the notion of
Furthermore, such loading puts a special emphasis a compelling scientific claim.
on the skills of the surgeon, which is why we rec-
ommend newly trained surgeons to only use a two- References
stage operation. A promising approach for those
who prefer a one-stage surgical protocol in combi- Albrektsson T: On long-term maintenance of the osseointe-
nation with direct or rapid loading is to use reso- grated response, Aust Prosth J 7(suppl):15-24, 1993.
nance frequency analysis in an effort to
differentiate potentially mobile implants from sta- Albrektsson T: Is surgical skill more important for clinical suc-
ble ones. cess than changes in implant hardware? Clin Implant Dent
Relat Res 3:174-175, 2001.
SUMMARY
Albrektsson T, Brånemark PI, Hansson H-A et al: Osseointegrated
It is important to observe that new biomaterials are titanium implants. Requirements for ensuring a long-lasting,
in need of careful physical and engineering investi- direct bone anchorage in man, Acta Orthop Scand 52:
gations to clarify if they are suitable for implanta- 155-170, 1981.
tion. In vitro studies may provide important
information, but one must remember that this is Brånemark PI, Zarb GA, Albrektsson T: Tissue integrated pros-
related to the controlled laboratory environment, theses: osseointegration in clinical dentistry, Chicago, 1985,
which differs from in vivo testing with its hormonal, Quintessence Publishing Co.
blood flow, and loading influences. It is therefore
not uncommon that in vivo findings are quite dif- Engquist B, Å´ strang P, Dahlgren S et al: Marginal bone reaction
ferent from those obtained in vitro. Short-term and to oral implants: A prospective comparative study of astra
long-term in vivo experimental studies are impera- tech and Brånemark system implants, Clin Oral Impl Res
tive before commercial clinical testing of an 13:30-37, 2002.
implant system is initiated. It is only when a bio-
material is found acceptable in such studies that Franke Stenport V: On growth factors and titanium implant inte-
clinical trials should be started. The most important gration in bone, PhD thesis, Biomaterials/handicap research,
step in the testing procedure remains the controlled, 2002, University of Göteborg.
preferably prospective, clinical study that should
span an adequate period, which is conventionally at Gotfredsen K, Karlsson U: A prospective 5-year study of fixed
least 5 years. partial prostheses supported by implants with a machined
and TiO2-blasted surface, J Prosthodont 10:2-7, 2001.
In the summary of current knowledge about the
factors controlling implant function in the body, it Gottlander M: On hard tissue reactions to hydroxyapatite-coated
is easy to say that the scientific community has titanium implants, PhD thesis, Biomaterials/handicap
made a great number of important findings in the research, 1994, University of Göteborg.
past 25 years. However, researchers may very well
be climbing the lower slopes of a mountain of Jacobsson M: On bone behaviour after irradiation, PhD Thesis,
unknown height. Major contributions will be gath- Biomaterials/handicap research, 1985, University of Göteborg.
ered in the future from prospective and controlled
treatment outcome studies in patients. The funda- Johansson C: On tissue reactions to metal implants, PhD thesis,
Biomaterials/handicap research, 1991, University of Göteborg.

Sennerby L: On the bone tissue response to titanium implants,
PhD thesis, Biomaterials/handicap research, 1991, University
of Göteborg.

Sul YT: On the bone response to oxidized titanium implants, PhD
thesis, Biomaterials/handicap research, 2002, University of
Göteborg.

Wennerberg A: On surface roughness and implant incorporation,
PhD thesis, Biomaterials/handicap research, 1996, University
of Göteborg.

Wennerberg A, Albrektsson T: Suggested guidelines for the
topographic evaluation of implant surfaces, Int J Oral
Maxillofac Implants 15:331-344, 2000.

Zarb GA, Albrektsson T: Osseointegration: a requiem for the
periodontal ligament? Int J Periodont Rest Dent 11:88-91,
1991 (editorial).

27C H A P T E R

Clinical Protocol for Treatment with
Implant-Supported Overdentures

George A. Zarb, Regina Mericske-Stern

Several compelling conclusions can be drawn from patients, it also escalated the costs involved
the chapters in Part 3: in managing the edentulous predicament. The
merits of the traditional overdenture technique
1. Treatment outcomes with complete dentures can therefore be combined with an implant
depend on both dentist- and patient-mediated prescription for a cost-effective version of
considerations. The former include clinical implant-supported prostheses.
judgment and technical skills, combined with 5. Clinical experience also shows that many
impeccable laboratory technological support. patients who request implant surgery
The latter are defined by systemic plus local because of denture-wearing problems are
health and morphological considerations, really in need of new optimized dentures, at
together with individual adaptive traits. least from an objective clinical point of
view. Patients must recognize that implants
2. An adaptive denture experience is the treat- do not compensate for technically and func-
ment goal, and it is frequently achieved. tionally inadequate dentures.
However, an ongoing long-term continuum
of adaptation may be unpredictable because We therefore regard implant-supported prostheses as
of time-dependent anatomical and physio- a logical outgrowth of the previously noted conclu-
logical changes. These include reduced sali- sions and think that they should be considered the
vary flow, compromised motor skills, severe standard of service for most edentulous patients, par-
residual ridge reduction, and an increased ticularly those with maladaptive dentures. However,
tissue vulnerability. fiscal realities, particularly in the context of aging
populations with fixed incomes, frequently preclude
3. The notion of a surgical solution for patients the fixed option. The overdenture choice, on the
with maladaptive dentures by means of other hand, could be regarded as more financially
enlargement of the available denture-bearing accessible and offers virtually similar advantages.
area (sulcus-deepening procedures, or ridge
augmentation, or both) has failed to yield pre- In this chapter we describe the application of
dictable and long-term beneficial results that the implant overdenture protocol as a routine
are morbidity free. Also, this solution does measure for managing the edentulous predicament.
not address the needs of patients who dislike
the idea of wearing dentures. OVERDENTURES TREATMENT GOALS

4. The introduction of the osseointegrated Overdentures supported by natural tooth roots have
implant protocol has eclipsed traditional pre- been a long-standing and integral part of treatment
prosthetic surgical techniques. It ushered in a planning. However, both their short- and long-
new era of versatile, predictable, and virtu- term treatment outcome can be unpredictable (see
ally morbidity-free implant prosthodontic Chapter 10).
treatment. Although this development has
enhanced the life quality of the treated

498

Chapter 27 Clinical Protocol for Treatment with Implant-Supported Overdentures 499

Although tooth and implant abutment attach- their connection to retention devices. There
ment mechanisms differ, their prosthetic role is is little doubt about the greater ease with
quite similar. Both can provide enhanced prosthe- which esthetic objectives can be addressed
ses retention and stability, and positively influence and achieved when using the overdenture
adjacent bone levels, although periodontal disease technique. This is not easy to accomplish
and caries are clearly not risk factors for the “anky- with the fixed prescription, more particu-
lotic-like” osseointegrated abutment. In fact, stud- larly in the maxilla, when moderate residual
ies of mandibular overdentures retained by ridge resorption has occurred.
implants have shown that bone height is very well 5. The dentist should seriously consider man-
maintained in the area where implants were aging both the patient’s surgical and prostho-
located. It should, however, be pointed out that dontic needs. The educational implications
resorption of the posterior residual ridge was of this conviction are profound ones indeed.
increased when compared with similar sites in
patients treated with implant-supported fixed pros- INCLUSION AND EXCLUSION CRITERIA
theses. It therefore seems prudent to suggest that
the younger the edentulous patient, the greater the Implant treatment decisions must be made for each
benefit from implant-supported fixed prostheses to patient according to individual circumstances. The
reduce overall long-term residual ridge reduction. major inclusion criteria underscore the quasi-uni-
On the other hand, overdentures should be recom- versal patient eligibility for the method (Box 27-1).
mended routinely for elderly edentulous patients Age itself is not an exclusion criterion; however,
because residual ridge reduction of their basal bone age-related factors frequently influence treatment
appears to be less vulnerable to residual ridge planning in elderly patients. Common problems
resorption. encountered include communication difficulties
(e.g., compromised hearing and cognitive skills)
The fabrication of complete dentures, partic- with consequent lack of cooperation; the likely
ularly mandibular ones for elderly patients with need for short appointments; special attention to
maladaptive dentures, is complex and difficult. presurgical measures such as general health status
Therefore a simple protocol that may be readily and information; oral hygiene state; and home care
applied to all elderly patients is a prudent objec- provision. Poor general health is often found in
tive. Such an approach includes the following elderly patients with consequent deterioration in
considerations: biological health that is far beyond their chronolog-
ical age. Therefore medical consultation is fre-
1. There should be a reduction in the number of quently required and is of course mandatory for all
prescribed implants: two in the mandible and systemically compromised and therefore high-risk
four in the maxilla. Although mandibular
treatment has been extraordinarily success- Box 27-1
ful, the moderate to severely resorbed maxilla
is a much bigger treatment challenge. Inclusion Criteria for Implant
Prosthodontic Treatment
2. Both patient and tissue stresses should be
minimized with a short surgical intervention. Patient desire for implant treatment
Systemic health status, which permits a minor
3. Implant abutment availability that ensures
denture retention and stability should not surgical procedure
compensate for technically and functionally Sufficient bone quantity to accommodate
inadequate dentures. Traditional and impec-
cable complete denture fabrication tech- prescribed implant dimensions
niques must be combined with the required Patient willingness and ability to maintain oral
surgical protocol to optimize the technique’s
potential. health status

4. Esthetic denture design should not be com-
promised by the location of implants and

500 Part Four Implant Prosthodontics

patients, if any suspicion of risk or unclear infor- assessment provides information about shape,
mation is present. The patient’s family physician width, and height of the residual ridges and soft tis-
should be routinely consulted. sue conditions. Horizontal and vertical relation-
ships of the residual ridges are examined, and
As mentioned earlier, problems with the wear- available space for the proposed implants and the
ing of dentures or adaptation to new ones are mul- planned retention devices is assessed. Most edentu-
tifactorial, including age-related considerations. lous patients who are treated with implants fre-
Patient selection criteria must therefore be estab- quently show advanced reduction of the residual
lished with respect to a broad range of local and ridges and absence of a wide band of attached
general aspects. Clinical experience supports the mucosa. This does not seem to adversely affect the
proposed exclusion criteria listed in Box 27-2, but health of the soft tissue attachment around implants,
also reveals that patients with a history of cardio- and gingiva-mucosal grafting is very rarely pre-
vascular disease, osteoporosis, and certain scribed. Where necessary, additional bone mapping
endocrine disorders are all able to undergo a suc- with a local anesthesia syringe needle helps iden-
cessful implant operation as long as their systemic tify the contours of the maxillary bone. This may
condition is not a brittle one. Surgical treatment be useful because of the thickness of the palatal
should also be carried out only when the patient’s mucosa, which may disguise the shape of the ridge.
health status allows it and when a patient feels well This is not necessary for the mandible and is
and is able to undergo the procedure. often impossible because the height of the floor of
the mouth does not permit easy identification of the
PRESURGICAL EVALUATION AND lingual shape of the mandibular bone.
TREATMENT PLANNING
Panoramic radiographs are made to overview
The treatment planning protocol is identical for all required bone dimensions, to “scout” anatomical
edentulous patients and is a result of clinical and structures, to discover possible pathological find-
radiographic assessments that yield the informa- ings, and to obtain general information on bone
tion contained in Box 27-3. The clinical oral quality or density. The panoramic film is, however,

Box 27-2 Box 27-3

Exclusion Criteria for Implant Specific Objectives of Treatment
Prosthodontic Treatment Planning for a Patient with

Patient’s current prosthetic experience is an Implant-Supported Overdentures
adaptive one
To determine the optimum location and num-
Residual ridge dimensions do not accommodate ber of implants in the context of the
preferred implant dimensions morphological aspects of the residual ridge

Communication with patient is not possible To design a favorable distribution for occlusal
because of his or her compromised cogni- stresses on the implants and the prostheses-
tive skills bearing tissues

Patient has a history of substance abuse To avoid discrepancies among the design of
General health conditions preclude a minor the dentures, the implants’ location, and the
dentures’ retentive devices
surgical intervention
Local anesthesia with a vasoconstrictor is con- To ensure an optimal esthetic result and
hygiene protocol
traindicated
Immunosuppressive therapy, prolonged intake of

antibiotics or corticosteroids, or brittle meta-
bolic disease history

Chapter 27 Clinical Protocol for Treatment with Implant-Supported Overdentures 501

not entirely reliable, and additional radiographic with metallic markers of known diameter may be
imaging is frequently required. In the maxilla, used to measure the available bone height on radi-
loosely structured trabecular or cancellous bone ographs and to predetermine a favorable location of
without a dense cortical layer is frequently encoun- the implants with respect to the topography of the
tered. As a result, the implants are frequently self- residual ridge and adjacent anatomical landmarks,
tapped into such bone of compromised quality. In such as the mandibular nerve or the maxillary sinus
the mandible, dense cortical bone frequently encloses (Figure 27-1). Cephalometric radiographs in par-
a tightly structural cancellous structure. Templates ticular provide information about faciolingual

AB

C

Figure 27-1 Correct imaging of potential host bone sites requires a mix of radiographs,
which can be rendered more accurate by using a template with metallic markers of known
dimensions (A). These markers will show up on a frontal (B) or sagittal image and allow for
measurement adjustments in bone height or width. Required sagittal views of anterior
edentulous zones are provided by means of cephalometric films or, less frequently, com-
puted tomograms (C).

502 Part Four Implant Prosthodontics

dimensions, plus the lingual aspect of the residual Figure 27-2 The maxilla’s ridge contour is
mandibular bone and the shape of the maxillary reflected in a segmented bar soldered to four implant
ridge. Tomographic images are rarely used for abutments. Retentive clips can engage any or all of the
mandibular interforaminal implant placement; five available segments, ensuring good retention,
however, they often are needed for maxillary optimal prosthetic teeth placement, and nonrestriction
treatment. of tongue space.

Examination of existing dentures helps the den- straight line, a bar will connect the two implants on
tist decide whether they are adequate for temporary its shortest distance and preferably parallel to the
use during the postsurgical healing phase. This is a patient’s arbitrary hinge axis (Figure 27-3, A). The
routine measure with the two-stage surgical proto- interimplant distance should preferably exceed 12
col. However, the transmucosal aspect of the mm to provide sufficient space to accommodate
Bonefit-ITI implants during the healing can be a retentive components. When a pronounced curva-
problem because the effort to prevent inadvertent ture of the mandibular ridge is encountered, the
loading in patients who are unwilling to remain placement of more than two implants is recom-
without dentures during the whole healing period mended. This arrangement will, however, virtually
may not be easily controlled. New or optimized convert prostheses support from an implant/ridge
dentures can be made before surgery if stability of one to a near exclusive implant support (Figure
old dentures cannot be achieved by minor adjust- 27-3, B). A shorter design of the bar segments will
ments. Old dentures are also examined regarding not interfere with the profile of the ridge.
their esthetic merits, plus the presence of loss of
vertical dimension of occlusion. Patients with advanced mandibular residual
ridge resorption will only accommodate shorter
The following two planning concerns of major implant lengths, and, consequently, more than two
prosthodontic treatment must also be considered: implants must be placed. In such situations, three
or preferably four implants should be prescribed to
1. Number of implants prescribed and their achieve sufficient intraosseous support.
location
Guidelines for selecting retentive devices are
2. Preferred denture retention devices discussed at the end of the chapter.

The number of implants placed for overdenture SURGICAL PROCEDURE AND THE
support differs in the mandible and the maxilla and OSSEOINTEGRATION PHASE
is influenced by residual jaw shape. Maxillary
overdentures require the placement of a minimum The surgical protocol is well documented, and the
of three to four implants, which are usually joined aim is to place the implants into predetermined host
with a connecting bar. In selected patients, two sites that address prosthodontic design objectives.
implants are used; however, the dentist must realize
that divergent implant axes, a curved shape of the
ridge, and unfavorable bone quality are specific
contraindications to the placement of only two
maxillary implants. In maxillary ridges, short bar
segments connecting multiple implants are sug-
gested because a segmented bar is more likely to
follow the ridge without encroaching on the palatal
space (Figure 27-2). Implant length should prefer-
ably be 10 mm or longer, and several implants
should be prescribed when resorbed host bone sites
preclude placement of 10-mm or longer fixtures.

Mandibular overdentures appear to be ade-
quately supported by two implants. When the ante-
rior mandibular ridge shows a slight curvature or a

Chapter 27 Clinical Protocol for Treatment with Implant-Supported Overdentures 503

AB

Figure 27-3 A, Mandibular overdentures have been shown to perform well when
supported by only two implants. These prostheses are implant/ridge supported and can be so
designed when implants are placed as far apart as possible between the mental foramina.
Use of a bar that allows for rotation of the prosthesis around the interimplant axis can be
achieved if anterior residual ridge shape is parallel to an arbitrarily determined hinge axis
that is only slightly curved. B, Residual ridge curvature (as opposed to the “flat” one in part
A) usually necessitates placement of three or more implants to preclude the splinting bar’s
encroachment on tongue space. However, a trade-off occurs if the bar’s segments follow the
ridge contour; the prosthesis is then virtually entirely implant supported. The same effect
probably results even if alternative retentive mechanisms are prescribed.

Therefore a surgical template or guide is recom- A healing phase of 3 to 4 months for mandibu-
mended to ensure optimal implant alignment and lar implants and 6 months for maxillary implants is
location, and this is facilitated by duplicating the usually observed with a longer interval prescribed
previous denture and trimming it as needed. The for compromised bone quality sites. Published
patient’s informed consent is obtained, and appro- research suggests that the healing process is a very
priate premedication is prescribed. The operation is individual response that may be accelerated or
carried out as atraumatically as possible, with the delayed in different sites in different patients. The
patient under local anesthesia. Postoperative phase dentist may be tempted to shorten the healing inter-
is almost always uneventful and is ensured by val, but this approach may be an imprudent one,
means of standard analgesia medication plus use of and we strongly recommend the previously men-
ice packs and chlorhexidine mouth rinses. After 7 to tioned guidelines.
10 days, depending on the wound healing process,
the sutures are removed, and the dentures are provi- PROSTHODONTIC PROTOCOL
sionally refitted with a tissue conditioner. The one-
stage implants should also be protected from Implant-supported and implant-retained complete
contact with the relined denture base, and therefore dentures resemble the clinical situation of overden-
the dentures are relieved overlying the implants’ tures supported and retained by specially prepared
location. The soft reliner must be changed at regu- natural tooth roots. Despite a lack of a periodontal
lar intervals, and patients are instructed to remove ligament and its periodontal receptors, the anky-
their dentures while sleeping to avoid trauma to the lotic-like osseointegrated attachment appears to
healing sites. Patients also are instructed about care- provide adequate sensorimotor feedback system
ful hygienic procedures with small soft brushes and through receptors in the oral mucosa, bone, tem-
the use of a mouthwash containing chlorhexidine to poromandibular joint, and muscle spindles. As a
facilitate plaque removal. result, coordinated chewing activity in edentulous

504 Part Four Implant Prosthodontics

and dentate subjects appears to be quite similar. It mouth, and laboratory implant analogues are con-
seems that the masticatory stability of implant-sup- nected to the transfer copings. The master cast is
ported overdentures during function compensates poured with the analogues in place. The subsequent
for the absence of a periodontal ligament. Patients clinical/laboratory protocol is identical to that used
with implants report high-functional satisfaction for complete denture fabrication. An exception is
and a sensation that they have their natural teeth. the inclusion of the selected retentive elements in
the fitting surface of the prostheses. For example,
Denture Design whenever a clip bar mechanism is used, the bar (1)
follows the shape of the ridge, (2) respects the posi-
The design and fabrication of implant-supported tion of the prosthetic teeth, and (3) provides access
overdentures follow the previously described prin- for oral hygiene procedures. The bar is cast, sol-
ciples of fabricating complete dentures as described dered to the prosthetic copings, and tried in the
in Part 3. Stability and retention of complete den- mouth. The same orientation index is used to cast a
tures are enhanced by provision of a well-fitting metal framework, should this be indicated, after
denture base and properly extended flanges. Where final soldering of the bar. The female parts of bar
desired by the patient, the denture base may be clip assembly are fixed directly in the denture base
slightly reduced in its extensions because of the during the laboratory processing procedures
overdenture’s relative immobility. This is usually (Figure 27-4). Some clinicians prefer to use a metal
the case with patients who object to prosthesis framework embedded in the acrylic resin denture
bulk. The replacement of lost tissue and the restora- base. In this case the female components should
tion of facial support are provided by the denture not be soldered to the metal framework. They are
base and the established vertical dimension of retained in the denture base with acrylic resin to
occlusion. These also become very important for facilitate future changes or repairs. Step-by-step
patients with intraoral defects resulting from max- clinical and laboratory procedures for fabricating
illofacial deficits that are caused by congen- the implant-supported overdenture are shown in
tial anomalies, trauma, or oncological surgical Box 27-4.
resections.
Guidelines for Selecting Retentive/Anchorage
The arrangement of anterior teeth follows basic Devices
guidelines as determined by facial esthetic needs,
whereas the arrangement of posterior teeth con- Several methods for securing retention and stabil-
tributes to retention and stability of the dentures. ity of overdentures are available. They are arguably
Individual patient preferences frequently can be equally efficient. However, certain considerations
fulfilled, but anterior teeth positions should not influence the choice of retaining element. These
interfere with the circumoral musculature. It is pre- include: (1) number of supporting implants and
sumed that a stable occlusion is likely to contribute their distribution over the ridge, (2) length of the
to the protection of implants from overloading. bar segments, (3) type and size of the single attach-
ment or bars, (4) number of female retainers, and
Clinical and Laboratory Procedures (5) degree of reduction of the residual ridge. Much
empirical discussion exists regarding the benefits
Prosthodontic treatment planning will result in of different retentive mechanisms (resilient versus
implant- and tissue-supported overdentures, rigid) (Box 27-5). A resilient retention mechanism
although a distribution of certain implant locations is widely recommended for anchorage of overden-
may lead to exclusive implant abutment support. tures to implants. The assumption is that this will
The impression technique is a crucial first step. protect implants from overload. However, recent
The preliminary impression is made with alginate results of comparative in vivo measurements of
in metal stock trays. The custom acrylic resin trays patients with two mandibular implants support-
require openings for accommodating the transfer ing an overdenture do not reveal a preference of
copings, which are placed on the implants. The one type of anchorage device or retention
final impression is made, it is removed from the

Chapter 27 Clinical Protocol for Treatment with Implant-Supported Overdentures 505

AB

Figure 27-4 The acrylic resin prosthesis may (A) or may not (B) be reinforced with a
Stellite alloy framework; this appears to be a subjective decision, although it clearly has
economic implications. The retentive clips (sometimes referred to as the female parts of the
clip bar) are processed and “fixed” in the acrylic resin denture base. This will make any future
clip replacement requirements a relatively easy procedure.

Box 27-4
Step-by-Step Prosthodontic Procedures

One ● Indexing of setups to allow for optimal bar
design
● Preliminary impression with irreversible
hydrocolloid for custom tray fabrication Laboratory: corrections as determined at try-in
appointment; bar fabrication
Laboratory: custom trays with openings over
implants’ location Five

Two ● Complete try-in, obtain consent of the
patient
● Abutment components selected (may
include additional prosthetic copings) ● Try-in of bar assembly, correction of cast-
ing if a passive fit is not obtained
● Mounting of transfer copings
● Full arch or two-stage impression with Laboratory: final corrections, preparation for
processing the denture: assembly of
custom tray clip/bar components
Laboratory: master cast with implant ana-
Processing the denture, occlusal equilibration
logues, wax occlusion rims on articulator to rectify processing errors

Three Six

● Jaw relation records ● Delivery of dentures to the patient
● Tooth selection ● Instruction about handling of the dentures
Laboratory: mounting the casts on the articu- ● Cleaning instructions for implants, reten-

lator, preliminary tooth setup tion devices, dentures
● Information about and enrollment in the
Four
maintenance care program
● Verification of occlusal records ● Baseline radiographs for comparative
● Esthetic and functional assessment of
monitoring purposes (optional)
tooth setup with the patient

506 Part Four Implant Prosthodontics

Box 27-5

Some Anchorage Devices Used for
Overdentures

Single Elements Figure 27-5 A horseshoe-shaped maxillary
● Single retentive anchors (stress-breaking prosthesis is made out of a combination of prosthetic
teeth, Stellite alloy (for strength with minimal bulk),
mechanism) and pink acrylic resin as a substitute for soft tissue
● Single magnet anchors (stress-breaking reduction and for esthetic support. The undersurface of
this prosthesis includes five retentive clips that engage
mechanism) the bar segments shown in Figure 29-3. Note that the
● Individually cast telescopic copings (rigid clips are retained in the acrylic resin segment to
facilitate any future repair needs.
mechanism)
for temporary use after the postsurgical healing
Splinted phase and before the insertion of technically time-
● U-shaped bar (rigid) consuming prosthetic reconstructions. It should be
● Round clip bar (stress-breaking mechanism) pointed out that the belief that spherical attach-
● Egg-shaped Dolder bar (stress-breaking mech- ments may be used to compensate for unfavorable
and nonparallel alignment of the implants appears
anism) to be a mistaken one.

mechanism over another. However, overdentures Indications for Bars Patients frequently complain
supported by “unjoined” implants are also reported about adequate lack of denture retention when single
to be successful. attachments are used—thus our preference for rou-
tine use of cast bars. Short distal extensions from
A popular belief among dentists is that bars rigid bars may additionally contribute to stabiliza-
may contribute to load sharing. The reported long- tion and prevent horizontal shifting of the dentures.
term success rate for mandibular implants is quite Bars are routinely recommended for maxillary over-
high, and slightly less so for maxillary implants. dentures, atrophic residual ridges in the mandible,
Because splinted multiple implants with a bar usually and mandibles with more than two implants due to
are prescribed for the maxilla, a horseshoe design is pronounced ridge curvature. When intraoral defects
possible (Figure 27-5; also see Figure 27-2). As a are present, rigid bars are preferred in an effort to
consequence, this type of maxillary overdenture minimize overload on adjacent vulnerable soft
will resemble a fixed prosthesis with regard to sta- tissues (Figure 27-7).
bility and function. Therefore it is understandable
that this may not be regarded as a realistic and eco- MAINTENANCE CARE
nomic alternative to a tooth-supported overdenture
or complete denture, as is the case with mandibular The objective of regular recalls for all patients with
overdentures supported by only two implants. overdentures is to maintain the health of the oral

Indications for Single Attachments The use of
retentive anchors or magnets is the easiest and
probably the most cost-effective way to retain den-
tures by means of implants. This is frequently rec-
ommended when implants are placed underneath a
patient’s presently worn dentures, that is, ones that
do not have to be remade. Denture-wearing prob-
lems of geriatric patients with impaired manual
dexterity may be readily resolved with such reten-
tion systems (Figure 27-6). They also may be used

Chapter 27 Clinical Protocol for Treatment with Implant-Supported Overdentures 507

AB

Figure 27-6 A large number of attachment devices have been commercially produced in
an attempt to enhance and diversify claims for optimal implant/prosthesis retention. Several
of these methods are backed by strong anecdotal support. They include spherical Dalla Bona
attachments (A) and magnets (B).

tissues, particularly the periimplant tissues, and to tenance of optimal care to prevent and help diagnose
check the denture for ongoing fit, stability, and potential problems has proven to be advantageous.
occlusion. The dental literature is full of scholarly Most patients with overdentures who are in special
discussions regarding the merits of periodontal need of oral health care are elderly. These patients
parameters and diagnostic methods borrowed from frequently possess impaired manual skills and
periodontology. Quite interestingly, they appear to reduced visual capacity. They are likely to have dif-
be of limited use in osseointegration, at least with ficulties in following cleaning instructions and
our two preferred implant systems. However, main- therefore rely on their care providers and their pro-
fessional assistance. They have to be taught indi-
Figure 27-7 A right mandibular resection vidual hygienic procedures that best correspond to
underscored the need for a stable prosthesis, otherwise their abilities. The wearing of overdentures cer-
precluded by resultant compromised tissues available tainly enhances plaque accumulation and risk of
for retention and stability of a complete denture. The inflammatory soft tissue reactions, but it is not as
prescription of two implants connected by a rigid bar ominous a concern where successfully osseointe-
met this patient’s needs for comfortable prosthesis grated implant abutments are used. Periimplant tis-
function. sues do not appear to be as vulnerable to plaque
by-products as periodontal tissues are, yet a variety
of nuisance type gingival responses may develop
and should of course be avoided. When compared
with an implant-supported fixed prosthesis, the
cleaning of implants and prostheses is certainly
easier with removable dentures (Figure 27-8).

Growth of hyperplastic soft tissue around
implants and particularly underneath the bars has
been observed and recorded. It usually is rectified
by a program of vigorous massage and most infre-
quently by surgical trimming of the excess tissue.
The patient’s maintenance program also includes
checkup and adjustment appointments. The latter

508 Part Four Implant Prosthodontics

A

BC
Figure 27-8 Popular adjuncts for ensuring continued soft tissue health including brushing
of circumimplant gingival tissue (A), deposit-free bar components (note use of a gauze
square) (B), and stimulation of tissues adjacent to the implants (C).

include an assessment of the fit of the denture base denture bases, bars, and attachments is a prerequi-
to determine the need for relining; an occlusal site for long-lasting health of the bone surrounding
assessment to establish need for intraoral or and supporting the implants.
“unmounted” occlusal adjustment; a check of
female attachment components (loose, broken, Bibliography
lost, or need for activation); and wear and tear of
any parts of abutment or retentive elements from Awad MA, Locker D, Korner-Bitensky N et al: Measuring the
contact with the denture base. effect of intra-oral implant rehabilitation on health-related
quality of life in a randomized controlled clinical trail,
The precise response to occlusal transmission J Dent Res 79:1659-1663, 2000.
of loads to the implants that might lead to bone
resorption or loss of osseointegration is unre- Awad MA, Shapiro SH, Lund JP et al: Determinants of patients’
solved. Research provides evidence that inade- treatment preferences in a clinical trial, Community Dent
quately fitting superstructures (even when not Oral Epidemiol 28:119-125, 2000.
recognized visually) may induce cumulative and
adverse stresses on implants, with a risk of adverse Benzing UR, Hall H, Weber H: Biomechanical aspects of two dif-
bone changes. Therefore a precise, passive fit of ferent implant-prosthetic concepts for edentulous maxillae,
Int J Oral Maxillofac Implants 10:188-198, 1995.

Bryant SR, Zarb GA: Osseointegration of oral implants in older
and younger adults, Int J Oral Maxillofac Implants 13:
492-499, 1998.

Chapter 27 Clinical Protocol for Treatment with Implant-Supported Overdentures 509

Cune MS, de Putter C: Comparative evaluation of some out- study. Part 2. Int J Oral Maxillofac Implants 9:63-70,
come measures of implant systems and suprastructure types 1994.
in mandibular implant–overdenture treatment, Int J Oral Mericske-Stern R, Steinlin Schaffner T, Marti P et al: Peri-
Maxillofac Implants 9:548-555, 1994. implant mucosal aspects of ITI implants supporting over-
dentures: a five-year longitudinal study, Clin Oral Implant
Cune MS, de Putter C, Hoogstraten J: Treatment outcome Res 5:9-18, 1994.
with implant-retained overdentures. Part 2: Patient satisfac- Mericske-Stern R, Zarb GA: Overdentures: an alternative
tion and predictability of subjective treatment outcome, implant methodology for edentulous patients, Int J
J Prosthet Dent 72:152-158, 1994. Prosthodont 6:203-208, 1993.
Mombelli A, Mericske-Stern R: Microbiological features of sta-
Duyck J, Van Oosterwyck H, Vander Sloten J et al: In vivo ble osseointegrated implants used as abutments for overden-
forces on oral implants supporting a mandibular overden- tures, Clin Oral Implant Res 1:1-7, 1990.
ture: the influence of attachment system, Clin Oral Invest Narhi TO, Geertman ME, Hevinga M et al: Changes in the eden-
3:201-207, 1999. tulous maxilla in persons wearing implant-retained
mandibular overdentures, J Prosthet Dent 84:43-49, 2000.
Enquist B, Bergendal T, Kallus T: A retrospective multicenter Oetterli M, Kiener P, Mericske-Stern R: A longitudinal study on
evaluation of osseointegrated implants supporting overden- mandibular implants supporting an overdenture: the influence
tures, Int J Oral Maxillofac Implants 3:129-134, 1988. of retention mechanism and anatomic-prosthetic variables
on periimplant parameters, Int J Prosthodont 14:536-542,
Feine JS, de Grandmont P, Boudrias P et al: Within-subject com- 2001.
parisons of implant-supported mandibular prostheses: Palmqvist S, Sondell K, Swartz B: Implant-supported maxillary
choice of prosthesis, J Dent Res 73:1105-1111, 1994. overdentures: outcome in planned and emergency cases, Int
J Oral Maxillofac Implants 9:184-190, 1994.
Hemmings KE, Schmitt A, Zarb GA: Complications and main- Quirynen M, Naert I, van Steenberghe D et al: Periodontal
tenance requirements for fixed prostheses and overdentures aspects of osseointegrated fixtures supporting an overden-
in the edentulous mandible: a 5-year report, Int J Oral ture: a 4-year retrospective study, J Clin Periodontol 18:
Maxillofac Implants 9:191-196, 1994. 719-729, 1991.
Smedberg J-I: Studies of maxillary overdentures on osseointe-
Humphris GM, Healey T, Howell RA et al: The psychological grated implants, Swed Dent J 102: 1-49, 1995.
impact of implant-retained mandibular prostheses: a cross- Von Wowern N, Gotfredsen K: Implant-supported overdentures,
sectional study, Int J Oral Maxillofac Implants 10:437-444, a prevention of bone loss in edentulous mandibles? A 5-year
1995. follow-up study, Clin Oral Implants Res 12:19-25, 2001.
Wright PS, Watson RM, Heath MR: The effects of prefabricated
Jemt T: Implant treatment in resorbed edentulous upper jaws, bar design on the success of overdentures stabilized by
Clin Oral Implant Res 4:187-194, 1993. implants, Int J Oral Maxillofac Implants 10:79-87, 1995.
Zarb GA, Schmitt A: Osseointegration for elderly patients: the
Johns RB, Jemt T, Heath MR et al: A multicenter study of over- Toronto study, J Prosthet Dent 72:559-568, 1994.
dentures supported by Brånemark implants, Int J Oral Zarb GA, Schmitt A: The edentulous predicament II: the longi-
Maxillofac Implants 7:513-522, 1992. tudinal effectiveness of implant-supported overdentures,
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Kiener P, Oetterli M, Mericske E et al: Effectiveness of maxillary
overdentures supported by implants: maintenance and pros-
thetic complications, Int J Prosthodont 14:133-140, 2001.

Meijer HJA, Starmans FJM, Steen WHA: Location of implants
in the interforaminal region of the mandible and the conse-
quences for the design of the superstructure, J Oral Rehabil
21:47-56, 1994.

Mericske-Stern R: Oral tactile sensibility recorded in overden-
ture wearers with implants or natural roots: a comparative

28C H A P T E R

Clinical Protocol: Implant-Supported
Fixed Prostheses

George A. Zarb, Steven E. Eckert

Successful osseointegration enables the dentist and tion to enable the dentist to determine where
the edentulous patient to consider one of two alter- implants can be located (Figure 28-1). Occasionally,
natives to the traditional complete denture experi- additional films such as tomograms or computer-
ence. These alternatives are an implant-supported ized tomograms (CAT scans) are requested. More
fixed or an overdenture prosthesis. This chapter sophisticated imaging techniques offer the surgeon
reviews some considerations that have an impact additional information about potential sites for
on the clinical decision making and protocol for implant placement and may be beneficial in deter-
fixed prostheses. mining situations that are not conducive to implant
placement unless bone grafts are placed prior to, or
PATIENT SELECTION in conjunction with, the implants. The treatment
decision is influenced by (1) the magnitude of resid-
Patients who have been shown to benefit most sig- ual ridge resorption; (2) the relationship to key
nificantly from osseointegration have been those anatomical landmarks: incisive foramen, nasal cav-
with a maladaptive denture experience. This truism ities, and maxillary sinuses in the maxilla and men-
has also led many denture adaptive patients “to tal foramina and inferior alveolar canal in the
trade in” their prosthesis for implant-supported mandible; and (3) the perceived quality of the pro-
fixed replacements. Consequently, this therapeutic posed host bone sites. A validated and predictive
option should be presented to every edentulous classification system for bone quality and quantity
patient seeking prosthodontic treatment as an alter- that is tied to implant outcomes is still to be devel-
native option to complete dentures. Current oped. However, clinical experience suggests that
research suggests that any patient whose systemic compromised bone quality and quantity may have
health does not preclude a minor oral surgical an adverse impact on treatment outcomes. This
intervention and whose proposed host bone sites appears to be a somewhat more compelling concern
can quantitatively and qualitatively accommodate in the maxillary edentulous arch.
the dimensions of the dentist’s selected implant
system and the entailed surgical protocol, as well as PRELIMINARY PROSTHODONTIC
afford the procedure’s expense, may be regarded as DESIGN
a candidate for osseointegration.
The decision to treat an edentulous arch with an
A clinical assessment identical to the protocol implant-supported fixed prosthesis is influenced by
articulated in this book’s early chapters is carried the following five crucial considerations:
out. The scrupulous clinical examination is aug-
mented with diagnostic cast and previous prosthe- 1. The number of the implant abutments. The
ses’ analysis (Box 28-1). It is then matched by a early, albeit compellingly documented, clin-
thorough imaging assessment. Usually, panoramic ical successes with implant-supported fixed
and cephalometric films provide enough informa-

510

Chapter 28 Clinical Protocol: Implant-Supported Fixed Prostheses 511

Box 28-1 or more implants should comprise a starting
point for a fixed design.
Considerations for Systemic Local 2. The location of the implants. Implant loca-
and Prosthodontic Treatment tion is more favorable when its distribution
or configuration is a curved rather than a flat
Medical History Contraindicating Treatment one. The former allows for more occlusal
units and an optimal cantilever design. A flat
● Systemic condition that precludes a minor oral implant arch form is probably a better can-
surgical procedure (e.g., brittle diabetic, blood didate for an overdenture design.
dyscrasia, immunologically compromised) 3. The quality of the host sites. Clinical expe-
rience suggests that loosely textured cancel-
● History of chemical dependency lous bone makes for a potentially vulnerable
● History of orofacial irradiation osseointegrated response. Consequently,
● Certain psychiatric disorders careful identification of optimal host site
● Heavy smoking (possibly) locators is essential, particularly because the
loading capacity of individual implants is
Local Considerations yet to be determined. The previously men-
tioned “formula” (five in the mandible, six
● Size of oral opening and interarch space in the maxilla) was gleaned from published
● Status of opposing dentition, if present (peri- and cumulative clinical experiences, and it
has clearly yielded impressive treatment out-
odontal health, overeruption, occlusal rela- comes. Furthermore, current clinical wis-
tions) dom has refined the formula aided by
● Quality and quantity of proposed host sites, improved and enhanced technology, for
which also requires a radiographic evaluation example, self-threading implants with an
● Height of smile line (circumoral activity) oxidized surface, plus a range of implants of
different lengths. It therefore appears pru-
Prosthetic Considerations dent to continue to use a five-mandibular
implant abutment design as a starting point
● Possible shortcomings in appearance, occlu- for a fixed prosthesis. The length of the pros-
sion, and support of previous dentures. Will the thetic cantilevers will depend on anticipated
presence of implants rectify such problems? patient occlusal activity because most
patients exhibit different degrees of magni-
● Relationship of prosthetic teeths’ positions to tude, duration, and frequency of functional
underlying residual ridges. Will a fixed pros- loading. However, the profession’s current
thesis resolve the perceived complaints inability to accurately predict the outcome of
entirely, or will excessive anterior and poste- implants in radiographically determined
rior cantilevering be required? poor quality bone suggests a need for con-
siderable caution when selecting such sites.
● Is the desired optimal position and support 4. The quantity of the host bone sites or the
of the circumoral tissues compatible with the amount of residual ridge reduction that has
proposed prosthetic teeth placement and the occurred. This is rarely a consideration in
location of the implants’ support? the mandible because mandibles measuring
less than 10 mm in vertical height in the
prostheses suggested a quasi-general for- intermental foramina region are infre-
mula: five implants placed between the quently encountered. It is, however, a fre-
mental foramina to support a 10- to 12-unit quent problem in the maxilla, where
fixed mandibular prosthesis. However, this grafting techniques may be required if a
formula did not address considerations of fixed prosthesis is planned. Alternative
arch form configuration (flat versus varying
degrees of curvature), length of implants,
length of cantilevers, and specific consider-
ations regarding diverse occlusal forces plus
the configuration of the implant/arch form.
The same applies to treatment planning the
maxilla, with the additional proviso that six

512 Part Four Implant Prosthodontics

A

C
B

DE

G
F

Figure 28-1 A comprehensive radiographic survey of edentulous jaws will enable the
dentist to ensure the presence of a healthy host bone site compatible with both quality and
quantity considerations. More than one view is necessary if a three-dimensional assessment is to
be made (unless there is access to tomography). All three views—panoramic (A), cephalometric
(B), and occlusal (C and D)—provide magnified dimensions of differing degrees. E and F are the
specific preoperative films, and G is the postoperative film of the patient in Plate 1-1.

Chapter 28 Clinical Protocol: Implant-Supported Fixed Prostheses 513

surgical approaches include sinus lift proce- SURGICAL STAGE(S)
dures and consideration of placement of
implants in the zygoma or pterygoid plates. The surgical technique is well described in the
Although both approaches offer exciting dental literature and consists of a sterile procedure
possibilities, there is still a lack of well- in which flaps are raised and holes are carefully
documented prospective studies to justify and gently drilled into the selected host bone sites.
their routine prescription. The holes conform to the chosen implants’ dimen-
5. Amount of circumoral activity or “generos- sions and accommodate the threaded tooth root
ity” of a patient’s smile line. This considera- analogues, which are frequently self-tapped into
tion applies almost exclusively to the place. The reflected mucoperiosteal flaps are
maxilla, where both the combination of a readapted to completely cover the implants if they
high lip line and advanced residual ridge are to be submerged and unloaded during the
resorption, or conversely, virtually no healing period. Note that the implants are provi-
resorption at all, may indicate challenging sionally sealed with a cover-screw during this
problems. The former will require the use of interim healing period. This is referred to as the
a visible labial flange to compensate for the two-stage surgical procedure. Alternatively, the
resorbed tissues. The size and design of such implants may be fitted with a “healing abutment”
a flange may preclude easy hygiene mainte- and the flaps readapted around them if the one-
nance and therefore contraindicate a fixed stage surgical procedure is selected. In either
prosthesis. As a rule, patients with extensive case, the soft tissues are sutured and the tissues
vertical and horizontal anterior maxillary left to heal undisturbed. During the 4- to 6-month
bone resorption are candidates for implant- healing period, the designated time required for
supported overdentures and not fixed pros- osseointegration to occur in the mandible and
theses. On the other hand, where little or no maxilla, respectively, the denture is relieved liber-
resorption is present, a high smile line is not ally and a tissue conditioner used to refit the den-
readily reconcilable with ideal implant loca- ture. When a second-stage surgery is required,
tion and angulation, which lends itself to an transepithelial abutments of selected dimensions
optimal emergence profile for the prosthetic are attached to the implants and the prosthodontic
teeth. In such morphological situations, the procedures started.
implant abutments cannot be readily located
in the anterior part of the maxilla, and, if fea- PROSTHODONTIC PROTOCOL
sible, are placed in the posterior zone.
The prosthodontic phase of treatment has as its
PRESURGICAL TREATMENT objective the fabrication of a cast prosthesis base
(metallic frame) that joins the implants together
The patient is carefully counseled about the pro- and provides distal cantilever extensions (Plate
posed treatment. The edentulous mouth is prepared 28-1). Artificial teeth and a soft tissue analogue
for the osseointegration technique by ensuring tissue could then be processed onto the framework. This
health, for example, correction of old prostheses and procedure allows for an electively removable pros-
use of tissue conditioners. Soft and hard tissue thesis that could be screwed to the osseointegrated
lesions that may have an impact on the surgical abutments. Other techniques have also been devel-
phase of osseointegration (e.g., hyperplastic tissue, oped to allow the use of screw- or cement-retained
frena, and exostoses) usually are addressed dur- metal ceramic prostheses. The discussion of such
ing the surgical osseointegration operation. prostheses’ construction is best left to publications
If there is inadequate bone, surgical procedures that specifically discuss fabrication of implant-
designed to generate new bone (so-called site devel- supported prosthesis.
opment) may be considered. Once an appropriate
site is established a surgical template is prepared, The design of the prosthesis, borrowed from
usually with the patient’s currently worn prosthesis both fixed and removable prosthetic protocols,
as a guide. seeks to reconcile traditional principles of occlu-
sion with optimal design for soft tissue health

514 Part Four Implant Prosthodontics

maintenance and esthetics. The clinical protocol alloy. Alternatively, a titanium frame can be
used comprises the following stages: employed. The latter technique is currently
regarded as being particularly accurate and,
1. Impressions are made in the dentist’s mate- moreover, lends itself to employing porcelain
rial of choice (e.g., a polyether material in a for both teeth and soft tissue replacement.
custom tray). An occlusal opening provides Framework design has gradually evolved into
access to transfer copings that are screwed a standard that reconciles principles of fixed
to the abutments. The transfer copings are prosthodontic frame waxing protocols with a
withdrawn in the impression and filled with predetermined tooth orientation.
laboratory analogues. The impression is 4. The framework is tried in the mouth, and
then poured in artificial stone. where an imperfect or nonpassive fit is
noted, the framework is severed. It is reassem-
2. A trial denture base stabilized with two bled on the implants with the retaining
prosthetic copings is used to register jaw screws and an index and returned to the
relation records. Subsequently, the same laboratory for soldering. The soldered,
base is used for a trial arrangement of the reassembled framework is tried again in the
artificial teeth. After patient approval and mouth.
confirmation of jaw relation records, an 5. Processing of the metallic framework and
index of the position of the artificial teeth is the stock acrylic resin teeth is completed
made. with a commercial acrylic resin; complete
denture laboratory technology is used.
3. The proposed framework is designed in the 6. The completed prosthesis is inserted in the
context of the teeth index positions and cast mouth, new jaw relation records are made,
and then surrounded by processed acrylic and the occlusion is refined on the articulator.
resin. The metallic frames are cast in a
silver-palladium alloy or a Class IV gold

Box 28-2

A Comparison between Presumed Advantages and Disadvantages of
the Three Current Therapies Available for Edentulous Patients

Complete Dentures ● Esthetic outcomes may be difficult and unpre-
dictable
● Relatively straightforward to fabricate
● Virtually universal in application ● Maintenance not always easy
● Inexpensive ● Size of occlusal table has to be reduced
● A preliminary option for first-time denture wearers
● All the shortcomings of artificial removable pros- Implant-Supported Overdentures

theses: psychological, tissue morbidity, risk of time- ● Stability, retention, and esthetic problems are
dependent maladaptation readily rectified
● Lifelong maintenance
● A “cure” for patients with maladaptive dentures
Implant-Supported Fixed Prostheses without the disadvantages of the fixed approach

● Conceptually brilliant and supported by com- ● Professional fees are not significantly higher than
pelling research data cost of complete dentures

● Limited in application ● Maintenance requirements do not appear to be
● Relatively complex to undertake demanding
● Expensive
● Enormous psychological and functional benefits ● Exhibit minor movement during function and
● A “cure” for patients with maladaptive dentures likely to accumulate food debris under the den-
tures’ fitting surface

● Size of occlusal table can be maximized

Chapter 28 Clinical Protocol: Implant-Supported Fixed Prostheses 515

Each patient is counseled about tissue and Henry PJ, Tan AE, Uzawa S: Fit discrimination of implant-
prosthesis care. Thereafter, a protocol for supported fixed partial dentures fabricated from implant
annual patient recall is followed. level impressions made at stage I surgery, J Prosthet Dent
77:265-270, 1997.
SUMMARY
Jemt T: In vivo measurements of precision of fit involving
The availability of a fixed treatment option is a implant-supported prostheses in the edentulous jaw, Int J
remarkable advance in prosthodontics. It is one of Oral Maxillofac Implants 11:151-158, 1996.
dentistry’s most gratifying treatment modalities, but
it demands considerable skill and judgment and a Jemt T, Book K: Prosthesis misfit and marginal bone loss in
high degree of patient commitment and understand- edentulous implant patients, Int J Oral Maxillofac Implants
ing. It also is quite expensive and comprises very 11:620-625, 1996.
strict inclusion and exclusion criteria as gleaned
from this chapter and Chapter 27. A comparison Krekmanov L, Kahn M, Rangert B et al: Tilting of poste-
between conventional dentures, implant-supported rior mandibular and maxillary implants for improved pros-
fixed prostheses, and overdenture treatments will thesis support, Int J Oral Maxillofac Implants 15:405-414,
help put these options in perspective (Box 28-2). 2000

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Prosthodont J 9(suppl):39-48, 1995.
Adell L, Lekholm U, Rockler B et al: A 15-year study of
osseointegrated implants in the treatment of the edentulous Rangert B, Krogh PH, Langer B et al: Bending overload and
jaw, Int J Oral Surg 10:387-416, 1981. implant fracture: a retrospective clinical analysis, Int J Oral
Maxillofac Implants 10:326-334, 1995.
Brånemark PI, Zarb GA, Albrektsson T: Tissue integrated pros-
theses: osseointegration in clinical dentistry, Chicago, 1985, Rangert B, Sennerby L, Meredith N et al: Design, maintenance
Quintessence. and biomechanical considerations in implant placement,
Dent Update 24:416-420, 1997.
Brunski, JB: Avoid pitfalls of overloading and micromotion of
intraosseous implants (interview), Dent Implantol Update Skalak R: Biomechanical considerations in osseointegrated
4:77-81, 1993. prostheses, J Prosthet Dent 49:843-848, 1983.

Desjardins RP: Implants for the edentulous patient, Dent Clin White GE: Osseointegrated dental technology, Chicago, 1993,
North Am 40:195-215, 1996. Quintessence.

Zarb GA, Schmitt A: The longitudinal clinical effectiveness of
osseointegrated implants: the Toronto study. Part I: Surgical
results, J Prosthet Dent 63:451-457, 1990a.

Zarb GA, Schmitt A: The longitudinal clinical effectiveness of
osseointegrated implants: the Toronto study. Part II: The
prosthetic results, J Prosthet Dent 64:53-61, 1990b.

Zarb GA, Schmitt A: The edentulous predicament. I. A prospec-
tive study on the effectiveness of implant-supported fixed
prostheses, J Am Dent Assoc 127:59-65, 1996.

29C H A P T E R

Managing Problems and Complications

George A. Zarb, Steven E. Eckert

Active treatment with osseointegrated implants period the second stage of treatment begins, during
usually spans a period of several months, and it is which the mucosa covering the implant is surgi-
possible that problems or complications may occur cally resected and transmucosal components are
at any time during this phase of treatment. Though connected to the implant. This is the two-stage
insertion of the finished prosthesis marks the end approach to implant surgery. In contrast to this pro-
of active treatment, follow-up maintenance and cedure, some implants are placed in such a way as
monitoring of the prosthesis, the implants, and the to allow an attached healing abutment to pass
host tissue’s response must continue for the life of through the oral mucosa at the first stage of treat-
the patient (Table 29-1). ment. Because there is no mucosa covering the
implant, there is no stage II surgery; thus this
The dental implant field is inundated with a process is known as a one-stage approach. In both
variety of techniques, designs and, of course, man- situations, efforts are made to avoid functional
ufacturers’ claims. In looking at this broad field the loading of the implant until the bone has a chance
dentist is often confused by the different approaches to heal adjacent to the implant and ensure an
used to place and restore dental implants. Likewise, osseointegrated response.
the complications that can occur with dental
implants seem to be quite varied. There is also a current and renewed enthusiasm
for the concept of immediate implant loading. This
An alternative to evaluation of the differences approach uses a rigid connection of implants
is to discuss the similarities among bone-anchored shortly after their placement within the jaw. Such
implants. All endosseous implants are placed in a rigid implant fixation allows the implants to be
surgical procedure, all must be made of a material used to support a prosthesis almost immediately
that is biocompatible and possesses favorable phys- after stage I surgery. These implants are called
ical and mechanical properties to function as reten- immediate load implants. In another approach,
tive and supporting mechanisms for dental implants are placed as freestanding supporting
prostheses, and all must undergo a healing process mechanisms for provisional individual dental pros-
to ensure long-term survival. Although there are theses. These single implants are generally not con-
variations on surgical techniques and implant mate- nected to teeth or to other implants but are used to
rials, these differences are generally minor. The retain provisional restorations that are placed in
required implant healing interval before occlusal cosmetic, but not functional load, conditions. This
loading, however, can and often does show greater approach is referred to as of an immediate provi-
variety. sional implant.

Implants that are designed to heal to the jaw- Although it seems that there are many different
bone may do so after a period of no mechanical approaches to implant use, careful scrutiny of the
trauma. This remains the classic approach used to different procedures demonstrates a number of
achieve osseointegration and requires a period of similarities. In the one-stage, two-stage, immediate
undistributed implant placement beneath the oral load, and immediate provisional implant approach
mucosa for 3 to 4 months in the mandible and 6 there is a period during which the implant must be
months in the maxilla. At the end of that healing

516

Chapter 29 Managing Problems and Complications 517

Table 29-1 complications in one area may affect the other, and,
Possible Problems and Complications consequently, at times there is no clear differentia-
tion between them.
Time Description
SURGICALLY RELATED COMPLICATIONS
Stage I surgery ● Unfavorable implant
Post–stage I surgery position/alignment Endosseous implant surgery can be described as a
one- or a two-stage procedure. Both techniques
Stage II surgery ● Swelling/ecchymosis demand placement of the implant within the
● Infection selected host bone site with a meticulous surgical
Postprosthodontic ● Suture remnants, wound procedure. A two-stage implant is placed in a posi-
insertion tion that allows the oral mucosa to be closed pri-
dehiscence marily over the implant, whereas a one-stage
Delayed ● Neuropathy implant is one that passes through the mucosa.
complications ● Failure to osseointegrate Both approaches require primary closure of the
● Unfavorable position or angle oral tissues in the interimplant spaces. Likewise,
both techniques require a period of undisturbed
makes implant unusable healing before the implant can be placed into func-
● Prosthodontic complications tion.
● Soft tissue complications
● Delayed loss of Surgically related problems can, in turn, be
subdivided into chronological order: those related
osseointegration to stage I surgery, to the osseointegration time
● Component fracture between the operations, and to stage II surgery. The
● Soft tissue complication surgeon will primarily deal with these occurrences;
however, it is often the dentist, having made the
protected from functional loading. The first two original diagnosis and treatment plan for the
approaches address this protection by avoiding patient, who will be consulted when a problem
force transmission to the implant during the early arises. As the prescribing and referring dentist, the
phases of healing. The immediate load approach patient’s closest association is with him or her. The
splints the implants to each other thereby creating a prescribing dentist must therefore be regarded as
rigid body that is relatively resistant to movement. that treatment plan’s architect and should be aware
In the immediate provisional implant therapy the of the possible complications that may occur dur-
implant is placed under minimal functional load ing this early phase of treatment. The dentist also
with the assumption that this load will not displace should be prepared to deal with the patient’s appre-
the implant sufficiently to interfere with bone-to- hensions and concerns and to make necessary
implant healing. Without bone-to-implant healing referrals to the surgeon.
the long-term survival of the implant is unlikely to
occur because the process of osseointegration will Stage I
be compromised or prevented. This complication,
failure to achieve or maintain osseointegration, is Any surgical procedure carries with it the risk of
regarded as the most crucial problem in implant bleeding, infection, swelling, and ecchymosis, and
dentistry. surgery for the placement of osseointegrated
implants is no exception. A meticulous sterile sur-
There are numerous ways to categorize the pos- gical technique, accompanied with appropriate
sible complications that can be encountered. They antibiotic prescription and instruction to the patient
may be referred to as early or late, surgical or regarding hygiene and oral rinses, is the best pre-
prosthodontic, biological or structural, functional ventive measure to reduce the chances of these
or esthetic, or hard tissue or soft tissue related. In sequelae. Excessive bleeding, if it occurs, is usually
this chapter, they are divided under the main head- noted at the time of surgery or soon after. If
ings of surgical or prosthodontic origin. This cate-
gorization relates to the phase of treatment rather
than the specific type of complication that is
encountered. However, it must be emphasized that

518 Part Four Implant Prosthodontics

observed, excessive bleeding is treated by the sur- surgical instruments or by the implant itself. With
geon. Swelling is often not at its peak until at least appropriate imaging techniques, paying attention to
the second day after surgery, but the measures nec- the details of the anatomy of the surgical field
essary to minimize it must be taken immediately revealed in these images and careful instrumenta-
after the surgical procedure. These include the tion will decrease the incidence of this complica-
application of pressure packs in the form of rolled tion. In most instances, the altered sensation will be
sterile gauze and the use of cold compresses or ice transient, though the transient time may vary from
packs. A transient and therefore insignificant a few days to several months. If damage to the
ecchymosis is also delayed in its appearance and is nerve has been severe, it may be permanent.
most likely to occur in patients who have a history
of bruising easily. Good preparation and tutoring of At stage I surgery, even when the most advanced
the patient will make it easier for him or her to imaging techniques are used, unexpected bony mor-
accept this temporary but unfortunate esthetic phological deficits or poor bone quality may pre-
appearance. clude ideal implant position, angulation, or the
number of implants placed. This has obvious reper-
Infection, if it does occur, may be evident cussions on the final prosthetic design and may lead
within a few days of the surgical insertion of the to a decision to change the prosthodontic prescrip-
implants, or it may not be manifested until a few tion. If a fixed prosthesis was originally prescribed,
weeks or even a few months afterward. If it is soon unfavorable implant angle or position could demand
after stage I surgery, it will most probably be noted a change to a removable prosthesis. Unfavorable
by the surgeon first and treated with a regimen of implant position or angulation could require change
antibiotic medication. If it is delayed, the patient to a different retaining mechanism for an overden-
may consult the referring dentist with a complaint ture if a removable prosthesis was initially pre-
of discomfort or soreness under the prosthesis. In scribed. It will sometimes lead to a decision to abort
such instances, there will likely be redness and the surgery if it appears that not enough implants can
swelling, and in some cases the infection will be be placed to support an implant-retained prosthesis.
accompanied by an exudate. Referral to the sur- The resolution of this complication is covered in
geon for debridement and cleansing of the site and other chapters of this book.
antibiotic therapy should be done without delay.
Interval between Stage I and Stage II
Suture removal is sometimes not complete
because of swelling or inaccessibility of the suture It is usual for patients to be requested to refrain
remnants. It usually is seen as a localized redness or from wearing their existing prostheses for a short
swelling and results in the patient experiencing dis- time after implant insertion. At the end of this
comfort when wearing the denture. This mucosal period, the tissue surface of the denture is relieved
irritation, sometimes mimicking infection, often is sufficiently to allow for the placement of a tissue
ongoing until the offending suture is removed. conditioner or temporary lining at least 1 to 2 mm
thick in the region of the implants. An existing den-
Occasionally, especially when there is signifi- ture that is of minimal thickness may be perforated
cant tugging on the sutures through movements of during this reduction unless it is made thicker by
the circumoral muscles or if the sutures loosen early, the addition of acrylic resin to its polished surface
the incision will reopen. If this occurs within a few beforehand. Because the surgical incision may be
days of stage I surgery, the surgeon may choose to found in the labial vestibule, final resolution of the
close the wound with new sutures. If it occurs later, swelling in the site often is not complete at 2 weeks
after the deeper layers of the wound have begun to after surgery. In this situation, it is usually neces-
close, the surgeon is unlikely to resuture choosing to sary to trim several millimeters from the length of
monitor the wound and request that the reinsertion the labial flange to prevent patient discomfort and
of the denture be delayed 1 to 2 weeks. stress on the incision site. This is true in either arch.

In rare instances, damage to the inferior alveo- Between the stages of the treatment, the soft
lar nerve may occur through a crushing injury dur- liner or tissue conditioner that has been applied to
ing the degloving procedures, or it may occur
because of violation of the canal or nerve by the

Chapter 29 Managing Problems and Complications 519

the tissue surface of the denture should be kept in If a dehiscence occurs where an osteopromo-
good condition. Doing so will eliminate possible tive membrane has been used, this site should be
ulcerations caused by the rough and hard flanges of monitored very carefully by the referring dentist
the dentures that develop as the soft liner ages. Soft and the surgeon. The denture base acrylic resin
liners that are old and rough also present a good should be reduced more aggressively in the area to
medium for increased bacterial growth. Keeping allow an extra thickness of tissue conditioner in an
the soft liner in good condition can be accom- effort to eliminate any possibility of pressure from
plished either by replacing it every 4 to 5 weeks or the denture causing an increase in the size of the
by treating the temporary liner and especially the dehiscence. The patient should be instructed to keep
seam between the soft liner and the denture base the site meticulously clean. Antibacterial rinses may
with a sealant that can be made up using an prove beneficial. At the first sign of infection, the
autopolymerizing acrylic resin powder and a sol- membrane should preferably be removed.
vent such as 1-1-1 trichloroethane (Box 29-1).
The time interval between the two surgical pro-
After the sutures are removed and the initial cedures often is difficult for the patient because
soft tissue swelling has reduced, dehiscence of the stage I surgery is a major event, and after initial
cover screw of the implant through the mucosal healing, an expected improvement in the denture-
covering may occur. Experience with one-stage wearing experience seems logical. It is important to
implants demonstrates that implant exposure is not stress to the patient beforehand that it will not be
a threat to the success of the implant as long as the any easier to wear the denture during the osseoin-
site is kept clean. The patient may experience dis- tegration phase of treatment and that it may even be
comfort if the dehiscence of the cover screw is not a little more difficult. It seems far easier for a
complete and there is still mucosa partially cover- patient to deal with this realization if informed
ing the screw. This tissue can be pinched between before trying to deal with a difficult situation
the cover screw and the denture base. It can be alle- between the surgeries.
viated by trimming back the soft liner that has been
applied to the tissue surface of the denture, thus Stage II
allowing clearance in the area and preventing the
pinching effect. Stage II surgery usually reveals whether an implant
has osseointegrated. There are times, however,
Box 29-1 when failure to osseointegrate is not detected until
the further instrumentation involved in the impres-
Recipe for Varnish for Tissue sion making or even the insertion of the prosthesis
Conditioner itself. If an implant is found to be mobile or tender
to percussion or to the stresses of attaching the
50 ml 1-1-1 trichloroethane abutment to it, it should be removed. Experience
2 ml autopolymerizing acrylic resin powder shows that leaving it in place, with or without
Using a glass bottle with a tightly closing lid, add antibiotic therapy, will not result in a failed implant
becoming osseointegrated. It will merely delay
the autopolymerizing acrylic resin powder to definitive treatment and could result in the devel-
the trichloroethane solvent. This will take a opment of a larger bone defect (Figure 29-1).
few hours to dissolve completely. The result-
ing solution should be as viscous as glycer- At stage II surgery, the cover screw that pro-
ine. If it is found that it is too thick, add tected the internal threads of the implant is removed
solvent; if it is too thin, add powder. and replaced with a transmucosal abutment and cen-
A small amount should be dispensed into a plas- ter screw or with a healing abutment. If the regular
tic medicine cup and applied to the entire sur- abutment is attached at this time, it is important to
face of the tissue conditioner, paying special ensure that the hexagonal female portion of the abut-
attention to the seam between the denture ment and the hexagonal male portion of the implant
base and the tissue conditioner. are properly aligned. If this is not the case, there may
be a soft tissue reaction or loosening of the compo-

520 Part Four Implant Prosthodontics

Figure 29-1 The radiolucency surrounding the PROSTHODONTIC-RELATED
implant on the left of the radiograph is indicative of an COMPLICATIONS
implant that has not osseointegrated. The implant was
mobile, and the patient reported mild discomfort when One of the earliest complications that can occur
it was tapped. On the right of the radiograph is an after stage II surgery and before prosthesis inser-
implant that has successfully osseointegrated and has tion is loosening of the abutment, whether it is an
no accompanying symptoms or signs of failure. abutment with a center screw or a healing abut-
ment. This results in an inflamed and painful soft
nents. This particular complication does not occur tissue reaction as the soft tissue grows into the
with the use of the healing abutment because there is space between the components and is pinched each
no internal hexagon to engage the one at the top of time the patient occludes. Though it can happen
the implant. The healing abutment does, however, with any type of abutment, it seems to occur most
seem to have an increased tendency to loosen. Thus frequently with healing abutments. When loosen-
care should be taken to tighten it securely to the ing of the abutment or healing abutment is noted, it
implant, and the patient should be advised to seek is important to evaluate the superior surface of the
attention immediately if loosening does occur. implant to ensure that there is no soft or hard tissue
covering the implant platform. Bone on the implant
Some of the complications encountered at stage platform can prevent full seating of the abutment,
I surgery become apparent only at stage II surgery which will in turn result in component malalign-
when the implants are uncovered and the abutments ment and a tendency toward increased incidence of
are connected. This is especially true of implants component loosening. To reduce this occurrence
that have an unfortunate buccal or lingual inclina- and to streamline the prosthodontic appointments,
tion or that are spaced too closely. If it is obvious at the surgeon should leave the chosen final abutments
the time of uncovering that the spacing or the align- attached to the implants after the final impression
ment will make it impossible to use the implant to for the prosthesis has been made. The top of the
support a prosthesis, the implant may be recovered abutments should be protected against damage with
or “put to sleep” during the surgical procedure. appropriate healing caps. It must be emphasized
that abutments can be damaged from contact with
opposing teeth and overlying hard material in the
provisional removable prosthesis.

Either immediately after stage II surgery or, if
preferred, the week after, the tissue conditioner or
the soft liner that had been placed into the patient’s
existing denture after stage I surgery is removed.
The position of the abutments attached to the
implants is transferred to the denture with an indeli-
ble marker guide, and then the denture is adjusted to
allow for a thickness of soft liner above the abut-
ments. Occasionally, the dentist will find that the
abutments emerge outside of the borders of the den-
ture, and then either the denture base must be
enlarged by the addition of autopolymerizing resin
or a change to a very short healing abutment, or to
an angled abutment is made.

Selecting the correct height of the abutment is
not always an easy procedure because there is usu-
ally some swelling present even after stage II sur-
gery. If the selected abutment is too short, the
mucosal swelling may lead to the tissue growing

Chapter 29 Managing Problems and Complications 521

over the top of the abutment or healing cap, thereby not be axially loaded by the forces of occlusion
allowing it to be pinched between the abutment and may be adversely affected. In that event, steps will
the relined denture base (Figure 29-2). If too long have to be taken to reduce to a minimum the mag-
an abutment is selected, it will be difficult to seat nitude of these forces, either by changing the pre-
the denture completely without perforating the scription to a removable prosthesis or by narrowing
denture base to make room for the height of the the occlusal table or by shortening the potential
abutment. If the denture is not adjusted sufficiently, cantilever arms.
the denture base will not be properly seated, and
the result will be an opening of the vertical dimen- Implants that are too close together will make it
sion. In some cases, the patient will be able to cope very difficult for patients with a fixed prosthesis to
with this increased height; in others, the resulting carry out oral hygiene procedures (Figure 29-3). In
vertical dimension will be both esthetically and the case of the overdenture, implants that are very
functionally so altered that the patient cannot or close together do not leave space for the ideal 1 cm
will not manage. In all of these scenarios, the prob- plus length of bar and clip, and when implants are
lem can be solved by changing the length of the closer than 3 mm, it is difficult to use standard ball
abutments. attachments. Recent introduction of the smaller
ball attachments with gold alloy or titanium keep-
The stage I surgical complication of insuffi- ers has helped to deal with this complication.
cient bone to allow ideal implant position and incli-
nation becomes most apparent at the time of Impression
prosthesis fabrication. Once the esthetic and func-
tional try-in of the tooth arrangement has been Obtaining an accurate impression for an implant-
accomplished and an index of the tooth arrange- supported prosthesis is made relatively routine
ment has been made, discrepancies between the because of the nature of the fit of the impression
ideal location and angulation of the implants and hardware that has been developed. There are, how-
the actual location and angulation become evident. ever, a few complications that may occur. If the
Implant manufacturers have been ingenious in their implants are close together and also are converg-
design of components to deal with these situations, ing, the impression copings may interfere with
but the basic problem remains. Implants that will each other. If their bulk is not reduced to eliminate

AB

Figure 29-2 One week after stage II surgery, the healing abutment, which was attached to
the center implant, is partially covered by mucosa. The patient reported acute pain and dis-
comfort as the covering tissue was pinched during wear of his denture (A). Replacement of
the shorter healing abutment with a longer one eliminated the discomfort and allowed the
inflamed mucosa to heal (B).

522 Part Four Implant Prosthodontics

AB

Figure 29-3 Six implants were inserted into this edentulous mandible where five
implants would have been ideal. The proximity of the implants results in a restriction of
space for the prosthetic cylinders and difficulty and discomfort in carrying out hygiene
procedures (A). For the problem to be fixed, the implant marked by the arrow is scheduled to
have its abutment removed and to be re-covered with mucosa (B).

this contact, the impression is likely to be inaccu- then be used to assess the accuracy of the master
rate. If there are widely diverging implants, there model obtained from the original impression. If it
may be a problem in seating the impression tray does not go into place passively when screwed to
over the impression copings and laboratory pins. the implants in the mouth, the jig can be severed at
Impressions will not be accurate if the hexagon of the offending connection, the sections seated and
the abutments and the implants are not properly screwed to the abutments in the mouth, and the
aligned and tightened before the impression is parts luted together. The altered jig allows for cor-
made. It may be prudent to confirm seating of the rection of the master model by drilling out the abut-
components with periapical radiographs immedi- ment analogue that was not in the proper place,
ately before making the impression. Radiographs attaching a new abutment analogue to the impres-
taken by the surgeon after stage II surgery are sion coping in the jig, and adding new dental stone
insufficient for this purpose because abutment to secure it. This resulting “altered cast” is then
screws may have loosened in the interim. Periapical used for fabricating the framework.
films are suggested because panoramic films will
not always reveal problems with the fit of the com- Try-in of Tooth Arrangement
ponent parts due to variations of the angles of the
implants. If there is even a moderate labial or lin- At this stage of try-in of the tooth arrangement, the
gual inclination of the implant, an unseated abut- effects of possible compromises made at stage I
ment may not be noted in a panoramic film. surgery become evident. Unfortunate inclination or
location of implants, whether due to anatomical
Even if the preceding precautions are taken, deficits of the host bone or to operator misjudg-
there are times when impressions will not be accu- ment, may make it necessary either to revise the
rate. We recommend fabrication of a confirmation prosthodontic prescription or to use alternate hard-
jig, which can be made by attaching impression ware components. A frequent example in the max-
copings to the abutment analogues on the master illary arch is one or more labially angled implants.
cast and then luting them together with acrylic An angled abutment will have to be used to avoid
resin or a light-cured material. The jig must be rigid having the gold alloy–retaining screw exiting from
to allow its use in confirming accuracy. For this the labial surface of the prosthetic tooth. This cor-
reason there must be sufficient bulk of acrylic or rects the esthetic concerns, but it does not correct
composite material to ensure rigidity. This jig can

Chapter 29 Managing Problems and Complications 523

for the nonaxial loading to which the implant will supported prosthesis. A few patients will note mas-
be subjected during function. ticatory muscle strain and fatigue during the first
weeks of wearing a mandibular prosthesis.
As a result of trying to attain both an estheti- Counseling the patient to avoid stressing the previ-
cally pleasing and functionally adequate tooth ously relatively inactive muscles of mastication by
arrangement, it may become evident that an origi- initially cutting food into smaller pieces and grad-
nally planned fixed prosthetic design will have to ually working up to normal chewing usually
be altered to a removable design (e.g., an overden- resolves this problem. The presence of stable den-
ture). Examples of such cases are implants that tal prostheses may encourage more rapid chewing,
have had to be placed in a straight line across the which could result in increased risk of cheek or
front of the mandible and significant labiolingual tongue chewing. Just as counseling is needed to
discrepancies between the maxillary and mandibu- avoid stress to the musculature, patients may bene-
lar arches. fit from the suggestion that they chew slowly until
they are accustomed to their new prostheses.
Framework Try-in
Potential esthetic problems are hopefully dealt
Producing a framework for a fixed implant pros- with at the tooth try-in stage of prosthesis con-
thesis involves several complex laboratory proce- struction. The situation is similar to the protocol
dures, and occasionally the result is a framework followed in complete denture fabrication. It must
that does not fit passively in the mouth. Sometimes be emphasized, however, that after final insertion,
this is visible to the operator; sometimes it is noted esthetic changes, although feasible, may be more
only by a response from the patient. This response awkward and tedious to be carried out after final
is most often a small wincing response by the processing is complete.
patient or a report of tightness that is alleviated
when the “offending” screw(s) is loosened slightly. Initial difficulties with speech may be anticipated
If either occurs, the framework is severed between with a maxillary fixed prosthesis, especially if there is
the segments that appear to fit passively but are a large difference between the location of the implants
clearly not doing so. Sometimes this will necessi- and the incisal edges of the prosthetic teeth. The bulk
tate severing in more than one site to ensure that of the prosthesis necessary to reach forward from the
there is no stress on the components as they are implant abutments to the prosthetic teeth can interfere
screwed into place. Once it is established that the with the tongue during normal speech. Though this
components fit completely and passively, they are problem usually resolves within a few days as the
luted together in the mouth with autopolymerizing patient’s tongue learns to cope, some patients find it
resin or light-cured composite, and the master necessary to wear an obturator for several months,
model is altered accordingly, as previously and very few will wear it indefinitely.
described. Then the casting is reassembled through
corrective soldering by the laboratory, and a second The incidence of speech problems also is
try-in appointment is scheduled. increased if the patient’s circumoral muscle activity
easily reveals maxillary gingival tissue. In these sit-
Though a nonfitting framework is more likely to uations, when the upper lip retracts during speech,
occur when there are several abutments being it will not form an air seal, and there will be a result-
joined together, there also can be discrepancies with ing “shshsh” when making the s sounds. When
bars joining as few as two abutments, especially if there is a high lip line, it may be necessary to add a
the implants diverge significantly from each other. flange to the prosthesis for speech and esthetics as
well. Though the flange solves these problems, it
INSERTION OF PROSTHESIS has the potential for creating other problems
because oral hygiene is made more difficult.
Implant-Supported Fixed Prosthesis
Implant-Supported Overdenture
Some complications can occur either at the time of
or immediately after insertion of the fixed implant- Insertion of the implant-supported overdenture is
sometimes complicated by the necessity to accom-

524 Part Four Implant Prosthodontics

modate both the soft tissue anatomy of the poste- Table 29-2
rior part of the mouth and the implant abutment Prosthodontic Problems and Complications
and hardware connection in the anterior. It may be
necessary to remove the otherwise useful exten- Type Description
sions into the retromylohyoid space to completely Structural
seat the overdenture. Prosthesis fracture
Cosmetic Fracture of prosthesis retaining screw
Some patients with implant overdentures find Functional Fracture of abutment screw
that food will collect under the anterior part of the Fracture of implant
denture, whether it be retained by a bar and clip As perceived by patient and dentist
assembly or by ball attachments. This is due partly to Speech problems
the relatively inaccurate impression of the anatomy Transient muscle discomfort or
here (remember that the impression tray had to be
made wider than usual in this area to accommodate temporomandibular disorders
the impression copings and was therefore too wide
to achieve an accurate impression of mucosa) and hood caused by an inadequate healing response
partly to the block-out around the retention hardware becoming compromised by subsequent loading
that was done before the final processing. A chair- demands. Meticulous treatment planning addresses
side addition of an autopolymerizing acrylic resin to the remote possibility of the small, if inevitable,
the lingual and labial flanges in this area usually failures. This will ensure successful prosthodontic
solves this problem. treatment outcomes even when fewer implants than
hoped for actually osseointegrated. The obvious
If a bar and clip assembly is used, the clip may example would be the conversion of a proposed five-
make it very difficult to remove the overdenture, unit fixed prostheses to a two- or three-unit overden-
unless it is loosened slightly before the first inser- ture if two or three implants should fail. Soft and
tion. It can easily be tightened after the other usual hard tissue problems are also encountered and are a
procedures of insertion of a complete denture are source of some controversy. A periodontic type of
completed. mindset considers such changes as a version of peri-
odontal diseaselike sequelae. On the other hand, sev-
In the first days after insertion of the overden- eral researchers, including this book’s editors, argue
ture, the patient may experience minor denture irri- for a mechanical and microbiological cause that
tations under the soft tissue–supported area of the challenges the implant’s surrounding gingival tissues
prosthesis. This is corrected as the denture is rather than its ankylotic-like attachment.
relieved and adjusted in the customary fashion.
Structural
POSTINSERTION
All of the three levels of components of the com-
During the years of prosthesis wear, there are a pleted implant-retained system are subjected to
number of possible complications that may occur. repeated stresses of occlusal and parafunctional
Some of these are common to both fixed and loading, and it is possible for these stresses to cause
removable prostheses, whereas others are more fractures of any of these components: the prosthetic
specific. The complications fall under the broad retaining screw, the abutment screw, or the implant
headings of biological and prosthodontic mechani- itself (Figure 29-4). Most common is the fracture of
cal ones (Table 29-2). the gold alloy screw, usually at the base of the head
of the screw. If the top of the threaded area is acces-
Biological complications include failure or loss sible, the screw fragment can be removed by care-
of integration and soft and hard tissue complica- fully touching the outside of the top of the fractured
tions. Because osseointegration appears to result piece, which is remaining in the center screw of the
from an induced and controlled healing response, it abutment, with a tapered fissure bur in either a
is not surprising that three fourths or more of all slow-speed handpiece or a high-speed handpiece
reported implant failures occur during the early
healing phase. The remaining failures occur after
occlusal loading takes place and are in all likeli-

Chapter 29 Managing Problems and Complications 525

running at very low speed. Another approach is to cult or if the screw fragment cannot be reached, the
use a hemostat to grasp the screw fragment and to entire abutment and center screw can be removed,
turn it counterclockwise to remove the screw. If the and the gold alloy screw can then be retrieved on the
screw is fractured beneath the top of the abutment, bench rather than in the patient’s mouth.
it may be teased out by engaging the top of the
screw with an explorer and rotating the explorer tip Cementing a fixed prosthesis would of course
in a counterclockwise direction. If this proves diffi- preclude fracture of retaining screws, but loosening
of the restoration can occur. Cementation is a pop-

A
BC

DE

Figure 29-4 Prostheses supported and retained by implants are subject to fracture within
the metallic framework (A), or the esthetic facing (B), or both (C). Component fractures are
possible at each of the levels of the implant-retained system, whether it be with the original
regular tube-shaped abutments (D) or with the currently used conical abutments (E). The com-
ponent most likely to fracture is the gold alloy prosthesis retaining screw a. The abutment-
retaining screw can fail at the head of the screw b or at the level of the threaded area c, which
usually is well within the implant itself. Fracture of the implant d is rare, possibly because of
the protective nature of the retaining components above it.

Continued

526 Part Four Implant Prosthodontics

F clockwise to remove the screw fragment from the
implant. Often this procedure is not as easily
Figure 29-4 cont’d The clinical photograph accomplished as this description suggests, espe-
(F) shows two implants with attached abutments. The cially if the abutment screw fragment seems to
abutment-retaining screw in the implant on the right is have bonded itself to the interior of the implant.
intact, whereas the head of the retaining screw in the Another approach is to very carefully prepare a
middle implant is fractured. On the left of this photo- “well” at the top of the screw fragment with a small
graph, the abutment is off because its retaining screw round bur (accompanied by generous irrigation)
has fractured at the threaded area, thus illuminating the and then to use a larger round bur, held either in a
retaining function of the screw. Retrieval of an abutment handheld torque driver or in the cutting tool holder
screw that has fractured within an implant must be done provided in the retrieval kit. The larger round bur is
with great care to avoid damage to the interior threaded pressed onto the prepared top surface of the screw
portion of the implant. and turned counterclockwise to remove it.

ular retentive approach in many clinical circles Removal can be further complicated by soft tis-
because it is presumed to be more “user friendly.” It is sue overgrowth or collapse into the space immedi-
argued that fixed prostheses can be easily recemented ately above the implant. Not only does this prevent
when natural teeth are used as abutments. However, a clear view of the top of the fractured abutment,
screw-retained prostheses are electively and easily but also there is often some bleeding because
removable, which we regard as a plus from a long- with a fractured retaining component, the implant-
term monitoring and maintenance point of view. supported bridge usually is mobile and pinches the
mucosa, causing it to become inflamed.
Fracture of the abutment screw can occur either
at the level of the hexagonal top portion or at the The instrumentation involved in an attempt to
spindle or threaded area deep within the implant. In remove the broken abutment screw must be used
the case of the fractured hexagonal top, removal with extreme care to avoid damage to the threads in
can be accomplished with a tapered fissure bur to the interior of the implant. If the internal threads of
create a slot into which a standard screwdriver is the implant have been damaged, it will be difficult
fitted. The center screw can then be easily reversed to insert the replacement abutment screw. In such a
out of the implant. case, the fixture tap, also included in the kit, can
then be used to repair the threads.
Removal of an abutment screw that is fractured
farther down its length is more difficult, and great The implant itself is also subject to fracture,
care must be taken to avoid damaging the internal though fortunately this is a very rare occurrence.
threads of the implant. The use of an explorer to The two upper levels of the system act as “fuses”
tease the screw out of its seat is described in the and usually will fracture before damaging stresses
previous paragraph. An abutment screw retrieval or can cause fracture of the implant. If an implant
rescue kit is available to use in cases where removal does fracture, it is usually at the level of the base of
is more difficult. The kit contains an end-cutting the abutment center screw, and, in most cases, it
tool that grasps the top of the fractured component happens when the bone level also has reached this
when pressure is applied. It is then rotated counter- point. The remaining implant fragment must be
removed by the surgeon using a trephine because it
almost always remains osseointegrated.

Whenever component hardware fractures occur,
the implant-supported bridge and its relationship
to the remaining dentition, the occlusal scheme, and
the presence and extent of cantilevers should be
assessed very carefully to determine if it is prudent
to make alterations to prevent further complications.
Long cantilever extensions, especially when implants
have had to be placed in straight-line configurations
rather than in a semilunar arrangement, seem to be

Chapter 29 Managing Problems and Complications 527

more frequently associated with component fracture. of implant restorations, Pract Periodontics Aesthet Dent
Even with the more desirable arch form implant dis- 10:737-746; quiz 748, 1998.
tribution, a heavy occlusal load on the cantilever Goodacre CJ, Kan JY, Rungcharassaeng K: Clinical complica-
portion of the bridge can cause fracture of the gold- tions of osseointegrated implants, J Prosthet Dent 81:537-552,
retaining screw or even the abutment screw at the 1999.
most anterior implant. Hemmings KW, Schmitt A, Zarb GA: Complications and main-
tenance requirements for fixed prostheses and overdentures
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Buchs AU, Levine UL, Moy P: Preliminary report of immedi- Piattelli A, Piattelli M, Scarano A et al: Light and scanning elec-
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Schnitman PA, Wohrle PS, Rubenstein JE: Immediate fixed
Eckert SE, Wollan PC: Retrospective review of 1170 interim prostheses supported by two-stage threaded implants:
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J Prosthet Dent 79:415-421, 1998. Schnitman PA, Wohrle PS, Rubenstein JE et al: Ten-year results
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Esposito M, Hirsch JM, Lekholm U et al: Differential diagnosis theses at implant placement, Int J Oral Maxillofac Implants
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Esposito M, Hirsch JM, Lekholm U et al: Biological factors osseointegrated dental implants: the Toronto study. Part III:
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contributing to failures of osseointegrated oral implants.
(II). Etiopathogenesis, Eur J Oral Sci 106:721-764, 1998.

Froum S, Emtiaz S, Bloom MJ et al: The use of transitional
implants for immediate fixed temporary prostheses in cases

30C H A P T E R

Implant Prosthodontics for Edentulous
Patients: Current and Future Directions

Emad S. Elsubeihi, Nikolai Attard, George A. Zarb

Osseointegration has had a dramatic influence on bidity has also become a significant consideration
prosthodontic practice. With its emphasis on scien- when prescribed surgical and prostho-
tific rigor, osseointegration now provides expanded dontic protocols are followed. This encourages
treatment management strategies for virtually all the conclusion, albeit a largely anecdotal but very
partially and completely edentulous patients frequently encountered one, that a patient’s life
(Plates 30-1 through 30-5). The clinical yield from quality is significantly enhanced by implant
osseointegration as summed up in Box 30-1 prosthodontics.
reflects the results of numerous studies on its effi-
cacy and effectiveness. Brånemark’s pioneering work in osseointegra-
tion catalyzed the conclusions in Box 30-1 and
In 1990 we reported the results of the first quite understandably led to several developmental
North American long-term prospective implant and research initiatives, which are summed up in
study in prosthetically maladaptive edentulous Box 30-2. Regrettably, very few of the available
patients (Zarb and Schmitt, 1990). One particularly systems have been validated in the literature
compelling finding was that successful prostho- (Eckert, Parein, Myshin et al., 1997), and claims
dontic treatment outcomes exceeded individual for predictably safe site development tend to
implant survival ones, and all of the treated patients remain long on anecdote, if somewhat short on sci-
demonstrated ongoing long-term comfortable and entifically documented outcomes. As a result both
successful prostheses wear. This study and subse- patients and dentists cannot readily answer the
quent ones strongly suggested that the provision of basic question that must be asked about any sys-
a fixed or quasi-fixed (overdenture) prosthesis was tem’s or surgical technique’s effectiveness evaluation:
the optimal solution to complete denture problems Do the proposed biotechnology and interventions
of a functional nature (prosthetic maladaptation). It lead to more good than harm in those people to whom
was concluded that the major determinant of suc- it is offered? This has become a dilemma in clinical
cess in wearing removable prostheses was patient- practice where advertised hype risks outweighing
perceived comfort and stability. The latter objective the quality of required long-term evidence, which
would be readily achieved irrespective of the number led to the compelling documented outcomes found
of successfully osseointegrated fixtures and under- in Box 30-1. It is hoped that continued efforts at
scored the merits of diverse applications of a tech- scientific validation will evolve into the yardstick
nique that has arguably revolutionized prosthodontic that dentists and patients will routinely use when
treatment. making clinical decisions on prescribing implant-
supported/retained prostheses and the associated
Furthermore, evidence now continues the con- protocols.
tribution of osseointegration to a slowing down, or
reduction, in the bone resorptive process that would It is encouraging to note that significant clini-
otherwise be likely to occur in the edentulous site(s) cal research initiatives continue to provide a better
of proposed implant placement. Additionally, the understanding of treatment outcomes with our pre-
documented virtual absence of even minimal mor- ferred implant systems, along with systemic and

528

Chapter 30 Implant Prosthodontics for Edentulous Patients: Current and Future Directions 529

Box 30-1 local determinants of successful osseointegration
(see Table 25-1).
Clinical Yield from Long-Term
Prospective Clinical Studies in HOST BONE RESPONSE

Osseointegration Long-term studies on the success/survival of dental
implants reveal an impressive prosthodontic treat-
1. Enhancement or guarantee of prosthesis ment outcome (Table 30-1). Because osseointegra-
retention/stability tion is essentially a wound healing process, it is
presumed that factors that interfere with the healing
2. Retardation in bone reduction process may contribute to implant failure. As a result,
3. Minimal treatment outcome morbidity in some studies investigators attempted to relate
4. Enrichment of patients’ life quality implant failure to the status of changes in bone qual-
ity or quantity. In other clinical studies researchers
Box 30-2 attempted to investigate the success rate of dental
implants in different systemic conditions that have
Research Developments been shown to adversely affect wound healing and
may therefore compromise successful osseointegra-
Developments in Implants/Implant tion (Elsubeihi and Zarb, 2002). Although the results
Components of some of these studies have provided some indica-
Implant material biocompatibility tions on conditions that can influence osseointegra-
Implant and component designs tion (Table 30-2), most did not provide conclusive
Implant surface characteristics evidence on the impact of systemic conditions on
dental implant success. The reason is that most of the
Developments in Surgical/Prosthodontic reported studies were either case reports or retro-
Techniques spective case series studies of small sample size. This
Surgical technique is further complicated by the fact that little is known
Implant placement technique about local hormonal, metabolic, and cellular
Site development processes in the jawbone. The reference section pro-
Timing of loading protocols vides more sources of information (Elsubeihi and
Zarb, 2002; Sennerby and Roos, 1998; Esposito,
Understanding Patient-Mediated Hirsch, Lekholm, et al., 1998).
Concerns
Local factors Smoking
Behavioral and systemic conditions
Quality of life It is estimated that implant failure is about twice as
Health economic benefits of treatments common in smokers as compared with nonsmok-

Table 30-1
Rate and Distribution of Early and Late Implant Failures in Two Studies

Total number of implants Meta-analysis Study* University of Toronto†
Early failure
Late failure 2812 1852
Overall failure 3.6% 4.21%
4.1% 3.66%
7.7% 7.9%

*Meta-analysis of 73 published studies over a 5-year period (Esposito, Hirsch, Lekholm, Thomsen, 1998).
†Data from prospective follow-up studies at the University of Toronto since 1979.

530 Part Four Implant Prosthodontics

Table 30-2
Summary of Influence of Various Factors on Implant Prosthodontic Treatment Outcomes

Local Patient-Related Factors Prosthodontic/Surgical Technique Implant-Related Factors
Systemic/Behavioral

No Demonstrable Age and gender Incision technique
Negative Effect*
Controlled diabetes mellitus Immediate loading

Controlled cardiovascular Exposed threads

disease Lack of bicortical stabilization

Controlled hypothyroidism Number of supporting implants

Hereditary ectodermal disease

HIV/AIDS

Systemic corticosteroid

therapy

Possible Risk of Maxilla in postmenopausal Clinician’s skill and experience Implant diameter
Failure women not receiving HRT Compromised infection control Implant design†
Jaw site Lack of initial stabilization
Vitamin D–dependent rickets Immediate placement in infected
Sjögren’s syndrome
Diphosphonate therapy extraction sockets
Distribution of implants

Increased Risk Cigarette smoking Lack of antibiotic prophylaxis Implant length
of Failure* Irradiated maxilla Implant material†
Compromised Recent chemotherapy

bone quantity
Compromised

bone quality

*Note that with the exception of smoking and diabetes mellitus, the influence of other systemic conditions on implant failure is based on case

reports and retrospective studies with small sample sizes.
†Implant microscopic and macroscopic characteristics are discussed in Chapter 26.

HRT, Hormone replacement therapy.

ers. Substantial evidence exists to support the con- ance between the amount of bone resorbed and the
clusion that cigarette smoking is associated with amount of bone formed. The available evidence
increased risk of implant failure, increased mar- examining whether one or both of these mecha-
ginal bone loss, and poor periimplant soft tissue nisms contribute to the bone loss associated with
health. In general, cigarette smoking has been smoking is limited. It has been demonstrated that
shown to impair soft tissue wound healing by affect- lower bone density at the lumbar spine in smokers
ing the circulatory and immune systems and by was associated with higher serum calcium and
impairing normal cellular function. Furthermore, it urine pyrdinoline levels, which is consistent with
appears that cigarette smoking during adulthood is increased bone resorption. Furthermore, it was also
associated with decreased hip and vertebral bone suggested that increased bone resorption associ-
density later in life in both women and men. ated with smoking is in part due to decreased pro-
However, the exact mechanism by which smoking duction and acceleration of degradation of estrogen
exerts its negative effect on bone is not yet fully leading to early menopause and higher rate of
understood. Bone loss occurs if there is an imbal- bone loss. On the other hand, histomorphometric

Chapter 30 Implant Prosthodontics for Edentulous Patients: Current and Future Directions 531

investigations suggested that reduced bone forma- fractures in rats indicated that ovariectomy impairs
tion is responsible for the deficit in bone volume fracture healing up to 4 weeks after fracture. This
seen in smokers. In vitro and animal studies have returned to normal levels 6 weeks after fracture.
shown that several components of cigarette smoke, The administration of 17-β estradiol during frac-
such as nicotine and aryl-hydrocarbons, can depress ture repair also resulted in a dose-dependent
osteoblast activity, reduce collagen synthesis, and increase in the peak force required to break the
inhibit osteodifferentation and osteogenesis. Other fracture. These observations may explain the recent
components of cigarette smoke, such as carbon findings of increased risk of maxillary implant fail-
monoxide (which binds to hemoglobin to form car- ure when tested with the reverse-torque method at
boxyhemoglobin) and hydrogen cyanide (which stage II surgery in osteoporotic patients not receiv-
inhibits cellular respiratory enzymes), result in tis- ing hormone replacement therapy. Interestingly, no
sue hypoxia and alter tissue healing. The effect of correlation was found between changes in bone
these components on jawbone behavior at the tis- mass in different parts of the skeleton and dental
sue and cellular levels needs to be fully explored. implant failure. This observation underscores the
need for a better understanding of the effects of
Irradiation Therapy systemic factors on jawbone changes at both the
tissue and cellular levels.
Irradiation therapy in which more than 55 gray (Gy)
was used has been associated with increased risk of Experimental evidence has shown that estrogen
implant failure and soft tissue complications during depletion leads to a significant loss of bone mass in
healing, particularly in the maxilla. It has been sug- the edentulous mandible, but not in the dentate
gested that the use of hyperbaric oxygen in these mandible, possibly because of the protective effect
patients can improve success rates, particularly in of masticatory forces (Elsubeihi and Zarb, 2002).
the maxilla. In addition to the known risk of osteo- The reduction in bone mass of the edentulous
radionecrosis, experimental evidence suggests that mandible of estrogen-depleted animals was associ-
radiation induces cellular changes in bone where ated with an increase in bone turnover where both
osteocytes in the direct pathway of irradiation are bone resorption and bone formation rates are
killed and the regenerative potential of the perios- increased, with the former exceeding the latter,
teum is compromised because of reduced cellular- resulting in bone loss. Evidence at the gene expres-
ity, vascularity, and osteoid formation potential. sion, cellular level, and tissue level in other parts of
Furthermore, blood vessels’ patency is reduced the skeleton further supports these findings.
leading to diminished hematopoietic turnover.
Several authorities maintain that a clinical diag-
Osteoporosis nosis of osteoporosis per se is not a contraindica-
tion for dental implant placement. However, in
The term osteoporosis has been somewhat loosely patients with a diagnosis of osteoporosis and where
used in the dental literature and often to imply the local jaw bone quality is judged to be of infe-
postmenopausal osteoporosis. Several reports sug- rior quality (e.g., Type IV bone, particularly in the
gest that osteoporosis is not a risk factor for maxilla), clinical prudence suggests the following
implant failure in the jaws; however, these were clinical strategy: self-threading implants should be
limited to case reports and case series studies placed with meticulous surgical technique, and an
where the diagnosis of osteoporosis was not con- appropriately longer healing period should be
firmed. Interestingly, biochemical analysis of bone allowed before subjecting the implants to high
derived from human osteoporotic femoral head occlusal stresses. The recent introduction of surface-
showed evidence of overhydroxylation of lysine modified self-threading implants may also prove to
and a consequent reduction in the stabilizing cross- be of value in these situations. Interestingly, func-
links of the collagenous framework that has been tional loading of healed dental implants in patients
suggested to contribute to increased fragility of may increase the bone mass in the jaws, an obser-
bone. Indeed, mechanical testing of healing femoral vation that is consistent with lack of effect of
estrogen depletion on the dentate mandibles of
animals.

532 Part Four Implant Prosthodontics

Other Systemic Conditions in the anterior mandible and somewhat lower ones
observed in the maxilla. This clinical observation
Case reports and retrospective studies with a small catalyzed research to improve success rates for
patient sample size indicate that there is an increased clinical situations where poor bone quality is
risk of implant failure in patients with Sjögren’s encountered. Examples include the following:
syndrome, patients with vitamin D–dependent rick-
ets, and in patients receiving active chemotherapy 1. Modification of the surgical technique:
and diphosphonate therapy. On the other hand, no underpreparation of host sites and the use of
evidence of increased risk of implant failure has osteotomes. The presumed advantages of
been demonstrated in patients with controlled dia- such techniques are bone preservation and
betes mellitus, controlled cardiovascular disease, localized increase in bone density of the
controlled hypothyroidism, HIV/AIDS, hypophos- osteotomy site.
phatasia, scleroderma, Erdheim-Chester disease,
and hereditary ectodermal dysplasia. It should be 2. Modification of the implant design: wider
emphasized, however, that with the exception of the diameters, changes in thread design, and
studies on smoking, diabetes mellitus, and irradi- introduction of self-tapping implants.
ated maxillae, the quality of most reports does not
allow for firm conclusions, and further studies are 3. Modification of implant topography by
needed. introducing roughened surfaces to increase
bone to implant contact.
THE SURGICAL PROTOCOL
However, the long-term benefits of such modifica-
Surgical technique and the healing potential of the tions, especially those related to surface modifi-
patient are local determinants of implant success. The cation, are still to be determined clinically. To date,
aims of the surgical technique are to place and locate long-term prospective studies have revealed pre-
the required number of implants (prosthodontically dictable prognoses for machined surface implants,
driven) in host sites as atraumatically as possible and even when the implant surface was exposed to oral
to obtain primary stability or implant immobility. This flora as a result of bone resorption. On the other
stability is dependent on the surgical technique used, hand, a rough surface, although reported to induce
plus the bone quality and quantity of the host site, more initial bone formation, may in the long-term
which in turn determines the length of implant used. be prone to infection-related problems due to the
risk of more enhanced bacterial adhesion. Further
An empirically based classification of bone research is clearly required to better understand the
quality and quantity was proposed by Lekholm and effects of implant surface topography in situ.
Zarb (1985) and describes commonly encountered
variations in jaw morphology or quantity, as deter- There are currently no specific tools that con-
mined by clinical examination and radiographic clusively determine bone quality before the implant
imaging. Bone quality is also described subjec- surgical intervention. Although computed tomog-
tively by the surgeon during the surgical procedure raphy remains a helpful diagnostic imaging tech-
(Figure 30-1). nique that provides insight into the architecture of
the bone, this does not necessarily guarantee suc-
Bone Quality cessful osseointegration. Further research at the
cellular level is also required to determine the var-
Bone quality in the mandible is typically cortical in ious steps of the healing phenomenon and to devise
nature anteriorly and more trabecular posteriorly. methods of harnessing and improving it (Watzek
Likewise, the maxilla is generally trabecular with and Gruber, 2002). Numerous attempts to coat
minimal cortical bone present in the alveolar implant surfaces with organic factors (bone mor-
process. However, alveolar bone is highly variable, phogenetic proteins [BMPs]) and inorganic materials
and the transition between anterior and posterior is (such as hydroxyapatite) that stimulate mesenchymal
gradual. Bone quality appears to influence treat- progenitor cell migration and differentiation have
ment outcomes, with high success rates described also been proposed. Regrettably, published results
are still inconclusive. Clinical experience indicated

Chapter 30 Implant Prosthodontics for Edentulous Patients: Current and Future Directions 533

12 34

Maxilla

A B C DE
Mandible

Figure 30-1 Lekholm-Zarb classification of edentulous anterior jawbone quantity and
quality. Types A through E reflect a range of resorptive patterns relative to the presumed
demarcation of the alveolar and basal jawbone (dotted line). Quality (Types 1 through 4)
reflects a range of cortical and cancellous patterns, which have been consistently used in
planning oral implant treatment.

that implant failure is a localized phenomenon. been suggested for compensatory ridge augmenta-
Site-specific healing potential is yet to be deter- tion, with the gold standard for bone grafting being
mined both at a morphological and cellular level. autogenous bone.
Furthermore, if this ability to do so was possi-
ble, this does not necessarily guarantee that such Research has established that a healing phase for
parameters would be useful predictors of osseointe- the graft is required before implant placement.
gration. However, the time required for this intermediate
phase before implant placement is yet to be deter-
Bone Quantity mined conclusively. Currently, the suggested interme-
diate healing phase is approximately 6 months.
Ridge reduction is an ongoing and cumulative Moreover, the impact of these surgical interventions
process, and the resultant residual bone quantity and associated morbidity still needs to be investigated
can compromise implant placement. Consequently, in elderly patients. This is a significant concern
several patients who are most in need of implants fre- because this age cohort will likely be the main recip-
quently have compromised bone anatomy. Various ient of implants.
surgical endeavors in the edentulous patient have
The need to find alternatives to autogenous
bone harvesting has also led to various research ini-

534 Part Four Implant Prosthodontics

tiatives. Basic science research in various animal Initially, patients seeking implant-supported
models demonstrated the bone regeneration capac- prostheses were treated with a minimum of five to
ity of various growth factors such as BMPs, tumor six implants in the anterior mandible and maxilla,
growth factor-β (TGF-β), platelet-derived growth respectively. These locations were selected because
factor (PDGF), and the maintenance of de novo of likely favorable host site dimensions. The
bone under functional loading. A dearth of infor- implants’ distribution followed the residual arch form
mation remains on the use of these regenerative so that they were better able to provide mechanical
materials in clinical studies, although short-term support for the prosthesis, and after a suitable heal-
results appear to hold promise. The need for mini- ing period (4 to 6 months), the implants were then
mally invasive preprosthetic surgical techniques to restored with a fixed prosthesis.
create better host sites for implants remains a seri-
ous research priority. Efficacy and effectiveness studies on patients
with maladaptive prosthetics who were treated
PROSTHODONTIC LOADING with fixed restorations show that these patients
were significantly helped with this technique (see
Occlusal forces are the major source of loading on Chapter 28). However, it should be realized that
dental implants. The basic tenets of a therapeutic this treatment modality is time-consuming and
occlusion were originally described by Beyron and expensive. Therefore we reiterate our conviction
underscore the standard determinants of a physio- that the dramatic impact of osseointegration treat-
logical occlusion in prosthodontic patients (Box ment should include a simpler, less dramatic appli-
30-3) (Mohl, Zarb, Carlsson, et al., 1988). cation of the technique. Since many experienced
prosthodontists have long recognized that most
These objectives are easily achieved in setting patients’ denture difficulties can be easily rectified
up teeth for complete denture fabrication (see if denture stability is improved, it appears logical
Chapters 16 and 17). However, their effectiveness that these patients do not necessarily need a con-
is also dependent on the quality of available resid- version of their unstable complete denture into a
ual ridge support. Occlusal loading potential in the fixed osseointegrated one. All they appear to need
edentulous patient is limited by the health and is a source of prostheses stability that can be read-
nature of the oral mucosa and the morphology of ily achieved with the presence of two or more
the denture-bearing area. As a result, patient suc- overdenture abutments. It is therefore tempting for
cessful acceptance of conventional prostheses, the prosthodontist to include such an “abbrevi-
notably lower complete dentures, remains a serious ated” use of osseointegration in the form of
treatment challenge and in the past led to numerous implant-supported overdentures. Such an applica-
ingenious surgical techniques to enlarge the den- tion offers both practical clinical and financial
ture load-bearing area. advantages. The surgical operation becomes a
reduced one, both time and money wise, and the
Box 30-3 approach is kinder to the patient particularly in the
context of the patient’s state of health or age.
Beyron’s Determinants of a Considerable evidence now endorses the functional
Physiological/Therapeutic benefits obtained by patients who wear implant-
retained overdentures. These benefits include
Occlusion improved denture stability, expanded scope for
aesthetic solutions, enhanced patient confidence
1. Acceptable interocclusal distance and comfort, and retardation of loss of the residual
2. Stable jaw relationship with bilateral contacts bony ridge height (see Chapter 27).

in retruded closure The initial proposed healing periods for the
3. Freedom in retrusive range of contact buried implants were an outgrowth of early trials
4. Multidirectional freedom of contact movement based on extrapolated observations from orthopedic
research. The original Brånemark osseointegration
technique required a two-stage surgical approach

Chapter 30 Implant Prosthodontics for Edentulous Patients: Current and Future Directions 535

with a minimum healing period proposed to obtain 4. The long-term success and economic bene-
durable direct bone to implant contact. This period fits of immediate loading in the context of
was suggested to be at least 4 months in the published treatment outcome criteria that
mandible and 6 months in the maxilla. justified use of traditional surgical and load-
ing protocols.
In the last decade, clinical research has ques-
tioned this timing protocol and led to altered imme- The biomechanics of the healing implant bone
diate or early loading treatment protocols, mainly interface remains a fascinating if complex concern
in site-specific areas. It should be understood that for various researchers, from tissue engineers to
if implants are loaded early, we are not dealing with clinical specialists. It appears that time-dependent
the biological phenomena of osseointegration per stress-strain states in mesenchymal tissue influence
se, but rather with primary mechanical implant sta- all differentiation in the various stages of bone
bility. The time-dependent secondary implant sta- healing. This occurs in fractures, in implant-related
bility is achieved when bone formation and osteotomies, and in distraction osteogenesis. It
remodeling at the bone/implant interface is com- must therefore be emphasized that current clinical
pleted. The presumed advantages of the change experiences with different implant-loading proto-
in time-related loading protocols include the cols (though ingenious and exciting) are based on
following: scrupulous observation exclusively and not on a
full understanding of the biomechanics of implant-
1. Treatment for routine patients with various bone interfaces.
implant designs, most particularly in the
parasymphyseal region of the mandible. This Oral Ecology and Implant Prosthodontics
area has the highest reported clinical success
rates when compared with the conventional Ecology is described as that branch of biology
delayed surgical approach. dealing with relations of microorganisms to one
another and to their physical surroundings. In a
2. A reduction or elimination of the healing broader sense it also includes the relationship
phase before loading of the implants with a between changes in a particular environment and
resultant reduced time commitment by the the resulting impact on specific presences or par-
patient. ticipants. Oral ecological responses to prosthodon-
tic interventions can therefore be regarded as a
3. One-stage surgery in an effort to reduce the balance between the implicit invasiveness of any
surgical morbidity. procedure (making crown preparations with sub-
gingival margins, using edentulous ridges for
Several published studies suggest that immediate occlusal support, implanting tooth root substitutes)
or early loading with fixed or overdenture and the host tissue site responses. Consequently,
implant-supported prosthesis is a viable option, at treatment techniques such as the ones mentioned
least in the short term. However, the results are may elicit changes that lead to specific ecological
far from conclusive, and a number of concerns upsets manifested as clinical complications. These
still need to be investigated to determine the include recurrent caries and periodontal disease
following: around a crowned tooth or inflammatory and mor-
phological changes in residual ridges under com-
1. The biological implications of reducing the plete dentures. The development of such adverse
healing time. ecological shifts are time dependent but also
reflect patient- and dentist-mediated judgment and
2. The true impact of such an approach on the skills. It is therefore quite remarkable to note the
patient’s quality of life. very minimal local or systemic morbidity recor-
ded in long-term prospective studies in implant
3. The specific protocol of immediate loading prosthodontics.
to be followed, specifically, the minimum
healing time required, the number of
implants needed to support fixed or over-
denture prostheses, and also the prosthetic
design.

536 Part Four Implant Prosthodontics

One fascinating fact has been the well-recorded odontal therapy protocols. A recent literature
observation that osseointegrated implants are very review (Esposito, Hirsch, Lekholm, et al., 1999)
rarely associated with postloading failure. Although concluded that the treatment of failing implants is
clinical skill and judgment, plus optimal patient still based on empirical considerations often
selection and operating protocols, appear to virtu- derived from periodontal experiments, from data
ally guarantee favorable long-term treatment out- extrapolated from in vitro findings, or from anec-
comes, the choice of implant per se also appears to dotal case reports performed on a trial-and-error
contribute to clinical success. basis. To date, no compelling data have been pre-
sented to justify treating teeth and implants as
When encountered, implant failure after identical clinical entities. Their attachment mecha-
prosthodontic loading has often been attributed to nisms are different because the tooth’s have
a so-called periimplantitis. This is described as an resulted from an evolutionary process, whereas the
inflammatory process affecting the tissue around an implant’s is an induced healing response (Figure
implant, which results in loss of supporting bone 30-2). As a result, functional differences between
and which has been reported in particular with implant and tooth are quite obvious (Table 30-3),
rough-surface implants. The latter observation yet numerous articles in the periodontal literature
may therefore suggest a greater vulnerability for and in some microbiological reviews have
implants with roughened as opposed to machined attempted to advance an argument favoring peri-
surfaces extending to their cervical regions, with odontitis-related bacteria as the cause of implant
an analogy with periodontal disease a long-stand- failure. It appears that the most serious conclu-
ing temptation. This in turn has led to several sions from such reviews are that the microflora of
hypotheses regarding the etiology of implant fail- periimplantitis resemble those of adult or refrac-
ure and a regrettable rigid insistence on a similar tory periodontitis and that potential periodontal
periodontitis and pathogenic etiology. It has even pathogens that are present in the mouth do not
led to treatment for periimplantitis based on peri-

A

Figure 30-2 A, In natural teeth, the structural continuity of tooth and periodontal
tissues is the product of a well-integrated series of developmental events.

Chapter 30 Implant Prosthodontics for Edentulous Patients: Current and Future Directions 537

B

Figure 30-2 cont’d B, In contrast to natural teeth, the structural continuity between an
osseointegrated implant and its host site is the result of a wound-healing process and not a
developmental one.

Table 30-3 Implants
Differences between Teeth and Implants
Interfacial osteogenesis (ankylotic-like) is an induced healing
Teeth response that is readily replicated

Attachment mechanism (periodontal ligament) is Immobile (ankylotic-like)
the result of evolution and has not been
replicated Cannot be intruded, extruded, or moved (ankylotic-like)
In young patients, implants are “left behind” while
Variable mobility is present; increased mobility
may be reversible surrounding tissues change
So-called osseoperception
Can be intruded, extruded, or moved A relative absence of such a sophisticated circulation and
In young patients, teeth continue to erupt
probably innervation
Proprioception Similar data are not present
Has a rich plexus of blood vessels and nerves

in the periodontal ligament
Data present to show progress of mucosal

inflammation to periodontal disease

necessarily act as periimplant pathogens. We quencies, and durations of occlusal loading. In this
regard available evidence as circumstantial at best, context, interfacial cracks may result, and these
more particularly because it appears to ignore the may eventually coalesce and lead to implant
likelihood of a compromised healing or osseointe- motion and in time a separation at the interface.
grated response, which could eventually succumb Secondary infection is then the likely outcome,
to the diverse and unpredictable magnitudes, fre- with complete loss of bony support the inevitable

538 Part Four Implant Prosthodontics

consequence. It is not surprising therefore that time, there is little doubt that both techniques can
failing implants demonstrate a microorganism address the edentulous individual’s needs. Both
environment usually associated with periodontal patients and dentists have already benefited enor-
disease. At this stage of our knowledge base it mously from this enriched spectrum of treatment
may even be tempting to conclude that the cause possibilities.
of implant failure is multifactorial and perhaps
that even genetic factors may play a role. References
However, our perception is that a reconciliation
of the healing process around an implant with the Eckert SE, Parein A, Myshin HL et al: Validation of dental
time-dependent nature of the load it is subjected implant systems through a review of literature supplied by
to remains the major determinant of implant suc- system manufacturers, J Prosthet Dent 77:271-279, 1997.
cess or failure. This conviction does not ignore
the fact that pathogenic microorganisms in Elsubeihi ES, Zarb GA: Implant prosthodontics in medically
plaque around teeth or implants may have sys- challenged patients: the University of Toronto experience,
temic health implications and that plaque should J Can Dent Assoc 68:103-108, 2002.
therefore be controlled.
Esposito M, Hirsch JM, Lekholm U et al: Biological factors
SUMMARY contributing to failures of osseointegrated oral implants. II.
Etiopathogensis, Eur J Oral Sci 106:721-764, 1998.
Scientifically acceptable treatment outcome time
frames for implant loading cover a spectrum of Esposito M, Hirsch J, Lekholm U et al: Differential diagnosis
possibilities. This spectrum ranges from over 20 and treatment strategies for biologic complications and fail-
years for machined commercially pure titanium ing oral implants: a review of the literature, Int J Oral
implants and traditional surgical protocols with Maxillofac Implants 14:473-490, 1999.
delayed loading, to virtually immediate loading
ones using various surgical methods of host site Lekholm U, Zarb GA: Patient selection and preparation. In
improvement and implants with roughened sur- Brånemark PI, Albrektsson T, Zarb GA, editors: Tissue-inte-
faces. Time, and even better research that includes grated prostheses: osseointegration in clinical dentistry,
economic benefits, will ultimately determine to Chicago, 1985, Quintessence.
what extent the complete denture will be eclipsed
by the implant-supported prosthesis. In the mean- Mohl ND, Zarb GA, Carlsson GE et al editors: A textbook of
occlusion, Chicago, 1988, Quintessence.

Sennerby L, Roos J: Surgical determinants of clinical success of
osseiointegrated oral implants: a review of the literature, Int
J Prosthodont 11:408-420, 1998.

Watzek G, Gruber R: Morphological and cellular parameters
of bone quality, Applied Osseointegration Research, 3:3-10,
2002.

Zarb GA, Schmitt A: The longitudinal clinical effectiveness of
osseointegrated dental implants: the Toronto Study. Part II:
The prosthetic results, J Prosthet Dent 64:53-61, 1990.

Index

A Adhesives (Continued)
Abutments contraindications, 444-445
cream vs. powder, 445
immediate denture definition of, 442
description of, 132 description of, 442
reduction of, 151, 152f indications, 444-445
trimming, 146-147 limitations of, 447
objective responses to, 443-444
implant patient education regarding, 445-447
complications of, 520 professional attitudes toward, 447
height of, 520-521 subjective responses to, 443-444

loosening of, 520 Age. See also Older adults
overdenture concealment of, 30
coordination declines associated with, 21
attachment mechanisms, 172f, 172-173 depression incidence based on, 22
caries associated with, 46-47, 162, 174 harmony considerations based on, 373-375, 374f
coronal reduction of tooth, 169, 171, 175 personal appearance concerns, 30-31
endodontic status of, 168
gingivitis around, 174f Aging. See also Older adults
gold copings for retention of, 171f, 171-172 bone loss associated with, 61
hygiene of, 173 concealment of, 30
location of, 167-168 edentulism and, 25
long-term monitoring of, 173-174 energy needs, 59
loss of, 172-174 global changes in, 24, 25t
maxillary teeth as, 169t income levels, 24
periodontal status of, 166-167 jaw movement changes, 27-28
preparation of, 168-173 life expectancy changes, 24
selection of, 166-173 natural appearance changes, 343-344
telescopic crowns for retention of, 173 nutrition changes, 28
tooth mobility considerations, 167 personal appearance concerns, 30-31
Acrylic resin. See also Polymethylmethacrylate population changes, 24, 25t
denture base, 195 premature, 343
denture teeth smell sense decreases, 28, 58
anterior, 303 taste sense decreases, 28, 58
description of, 19t, 195, 197-198 teeth color changes, 30
posterior, 306
hollow obturator prosthesis capped using, 469-470 Ala nasi, 348f
shrinkage of, 404 Ala-tragus line, 262, 262f
trial denture base, 254 Alcohol abuse, 60-61
water absorption by, 425 Alginate, 221
Actinomyces, 46 Alkaline hypochlorites, for denture cleaning, 204, 205t
Adhesion, 438 Aluwax, 339-340, 406
Adhesives Alveolar bone loss, 61
components of, 443 Alveolar groove, 237f
Alveolar process
Page numbers followed by “f ” denote figures, “b” denote boxes, and
description of, 11
“t” denote tables.

539

540 Index

Alveolar process (Continued) Arch
direction of, 352 anteroposterior position of, 309
description of, 258-259
Alveolar ridge harmony of, 362-364, 363f-364f
augmentation of, 116 mandibular, 259-260, 260f, 365
hamular notch obliteration, 116 maxillary, 260-261, 261f
hyperplastic, 102-103 midline of, 310f, 365
integrity of ovoid, 363, 363f-364f
existing teeth for maintaining, 160 single edentulous, 427
periodontal ligament effects, 12, 160 soft tissue considerations, 259
residual. See Residual ridge square, 362, 363f-364f
resorption of. See Residual ridge, resorption of tapering, 362, 363f-364f
vestibuloplasty of, 110-111, 113, 116, 118f-119f
Articulating paper, 410f-411f
Alveolingual sulcus, 91, 237f, 241, 243 Articulator
Amylase, 15
Angular cheilitis centric relation verification using, 331-335
definition of, 291
Candida-associated stomatitis and, 38 Dentatus, 339-342, 401f
clinical features of, 28, 29f, 36, 37f errors in, 295
Angulus oris, 348f-349f hinge, 291, 292f
Anterior teeth jaw movements recorded using, 265
artificial jaw relation records transferred to, 284-285
mandibular relation to, 291, 291f
anteroposterior positioning of, 309f, 351-356 maxillary relation to, 289-290, 290f
arch form of, 363-364 occlusal errors corrected on, 404-405, 405f
articulator programming for, 294 programming of
incisal wear and age, 368-369, 369f-370f
inclination of, 361f, 361-362 arbitrary settings, 295-296
long axes of central incisors, 364-365, 366f condylar elements, 294
mandibular, 311-313 description of, 294
maxillary incisal elements, 294-295, 295f
protrusive interocclusal records, 338-342
description of, 310-311 remounting on
labiolingual inclination of, 369, 371f cast for, 399, 400f
observation of, after removal of trial denture base, 354, interocclusal records for, 405-406
selection of, 292-294
358f semiadjustable, 293f
placement of, 306-307, 310f types of, 291-292
repositioning of, 350 Whip Mix, 338-339
rotational positions of, 370 Artificial teeth. See Denture teeth
selection of Asymmetrical symmetry, 366, 368f

characterization of selected teeth, 303-304, 304f-307f B
color, 301-302, 351 Balanced occlusion, 414
considerations for, 351 Basal seat
description of, 298
environmental setting, 301 changes in, 473
gingiva considerations, 303 irritation in, 425
mold for, 302, 302f modifications in, 476
patient preference considerations, 303 Basal surface errors, in denture, 402-404, 403f-404f
patient’s involvement in, 299-303 Base, denture. See Denture base
photographs used for, 300, 300f Basocellular carcinoma, 42f
shade guides, 298, 299f, 302 Beeswax occlusion rim, 331, 331f
size, 302 Bilabial speech sounds, 381-383, 382t
timing of, 302-303 Biological price, 100
trial denture base, 359 Biomaterials
vertical orientation of, 356-361, 359f-360f copolymers, 190-191
immediate denture denture-lining
decoronation of, 153
setting of, 144, 146-147 description of, 198
natural long-term soft liners, 200, 200b
irregularities of, 370, 372 plasticized acrylics, 200-201, 203b
labiolingual inclinations of, 371f self-administered home relines, 200
Anteroposterior compensating curve short-term soft liners, 198-200, 199b
for balanced articulation, 318, 318f
for lingualized articulation, 322

Index 541

Biomaterials (Continued) C
silicone soft liners, 201 Calcium

denture teeth absorption reductions, 61-62
acrylic resin, 195, 197-198, 198t bone health and, 61-62
composite resin, 197 dietary reference intake recommendations for, 61, 62t
description of, 195 food sources of, 62
porcelain, 197, 198t, 306 supplementation, 62
requirements of, 197b woman’s intake of, 61
Candida infections
requirements, 191b signs of, 86
Bite force stomatitis, 35-40
Canines
adhesives effect on, 444 mandibular, 311, 371f
age-related declines in, 47 maxillary, 311, 371f
amount of, 10 Caninus, 352f
denture effects, 417 Carborundum paste, 412
teeth effects, 9 Caries
Boil-out, 149, 150f fluoride prophylaxis, 174
Boley gauge, 277, 280f, 302f overdenture-related, 46, 162, 174
Bone Cast
calcium for, 61-62 diagnostic
characteristics of, 87
health assessments of, 87-89 description of, 83
Lekholm-Zarb classification of, 533f immediate denture uses of, 130, 132f
metabolic diseases of, 87-88 occlusion evaluations, 130, 132f
older adult changes in, 26-27, 61 vertical dimension of occlusion determined using, 275,
quality of, effect on implants, 532-533
quantity of, effect on implants, 533-534 276f
radiographic assessments of, 80 mandibular denture, 256f
remodeling of, 45 maxillary denture, 229, 230f, 255f
turnover of, 27 remounting, 399, 400f
vitamin D for, 62 Cast metal alloys, for denture base, 205-207, 206, 206f
Bone grafting Cemento-enamel junction, 391
autogenous, 533-534 Central incisors
healing phase before implant long axes of, 364-365, 366f
mandibular, 371f
placement, 533 maxillary, 309-311, 369
mandible, prostheses for, 466-467, 467f mesial rotation of, 373f
Bone morphogenetic proteins, 532 square arch, 362, 364f
Border molding Central pattern generators, 380
mandibular dentures, 246-248 Centric occlusion
maxillary dentures, 225-227, 228f correction of errors in, 410f
Boxing description of, 19, 90, 283
mandibular impressions, 249, 249f Centric relation
maxillary impressions, 229, 230f correction of, 331, 331f
maxillofacial prostheses, 468 definition of, 18-19, 92, 283
Branemark, Per Ingvar, 4, 484, 528 errors in, 330, 331f
Bruxism, 16 interocclusal record of, 406-407
Buccal flange, 237f-238f, 421 record of, 265-266, 288-289
Buccal frenum, 216, 217f, 237f significance of, 284
Buccal notch, mandibular, 237f-238f verification of
Buccal shelf, 232-233, 234f, 237f
Buccal vestibule description of, 408-409
anatomy of, 217, 237f-238f, 238-239 extraoral articulator method for, 331-335
impression taking of, 223 intraoral observation of intercuspation, 330-331
Buccinator, 216, 239, 261, 348 Characterization, of denture teeth, 303-304, 304f-307f
Burlew foil, 152 Cheeks, muscular evaluations of, 93
Burning mouth syndrome Chemically activated resins, for denture base, 191b, 193-194,
description of, 42-43 196t
etiologic factors of, 43b, 43-44 Chewing
management of, 44 adhesives effect on, 444
psychogenic factors, 43b, 43-44 age-related changes in, 28

542 Index Complete denture (Continued)
mastication effects, 15-16
Chewing (Continued) masticatory movements, 16
denture-wearing effects on efficiency of, 47, 57, 416-417 maxillary. See Maxillary denture
teeth primarily used for, 16 mucosal support for, 10-11
muscle activity effects, 21
Chlorhexidine, 47 natural teeth vs., 16
Choking, 59 neurological diseases and, 444
Christensen phenomenon, 284 nutrition care for. See Nutrition
Cigarette smoking, 496, 529-531 occlusal surface of, 252, 253f, 440f
Cleansers, denture. See Denture cleansers occlusion for
Cobalt-chromium alloys, for denture base, 205-206 balancing contacts, 324-325, 326f
Coble device, 282f description of, 19, 269
Cohesion, 438-439 maximum intercuspation, 324, 324f
Color of teeth modifications, 324-327
protrusive contact prevention, 325-327, 327f
age-related changes, 30 schemes, 313-323
anterior teeth selection, 301-302, 351 working contacts, 324-325, 326f
Communication older adult use of, 25
doctor/patient, 183-184 oral environment, 34
effective, 181-183 parafunctional habits, 16
environment effects, 180 patient instructions regarding
functions of, 180-181 appearance, 416
history of, 178-179 educational materials, 418-419
importance of, 180-181 individual differences, 416
model of, 178-180 mastication, 416-417
nonverbal language, 182 oral hygiene, 417-418
overview of, 177-178 overview of, 414, 416
physical reactions, 182 residual ridge preservation, 418
physiology of, 179f, 179-180 speech changes, 417
schematic diagram of, 179f patients’ evaluation of, 401
scope of, 178 periodic recalls to evaluate, 426
self-awareness and, 181 polished surface of
Complete denture anatomical portion, 390-391
adaptive responses, 20-22, 386 art portion, 390
adjustments description of, 252, 254f, 439f
waxing of, 390-392
denture base, 420-424 posterior teeth for. See Posterior teeth
occlusal, 420 presumptions regarding use of, 484f
advantages of, 514b residual ridge. See also Residual ridge
anterior teeth for. See Anterior teeth description of, 11-13
articulator for, 292-294 reduction of, 17-18
basal seat retention of
changes in, 473 adhesion, 438
irritation in, 425 adhesives for. See Denture adhesives
modifications in, 476 atmospheric pressure, 441
base of. See Denture base cohesion, 438-439
behavioral responses, 20-22 description of, 12-13
bone loss associated with, 12 factors that affect, 437-442
border tissues for, 90-91 gravity, 442
centric relation for, 18-19 interfacial force effects, 437-438
contraindications, 486b oral and facial musculature effects, 439-441
dentists’ evaluation of, 400-401 parallel walls for, 442
disadvantages of, 514b psychological effects on, 14
discomfort associated with, 16-17 rotational insertion paths for, 441
follow-up care, 419-426 surface tension effects, 437
friends’ evaluation of, 401-402 tongue base, 441
inaccuracies in, 402 undercuts, 441
loosening of, 420, 423, 473 rotary movement of, 473
maintenance of, 471
maladaptive, 3-4
malnutrition risk factors, 64b
mandibular. See Mandibular denture
mandibular process height changes, 18

Index 543

Complete denture (Continued) Dental arch (Continued)
sequelae caused by maxillary, 260-261, 261f
burning mouth syndrome. See Burning mouth syndrome midline of, 310f, 365
caries, 46 ovoid, 363, 363f-364f
control of, 49 soft tissue considerations, 259
denture irritation hyperplasia, 40, 41f, 418 square, 362, 363f-364f
flabby ridge, 40, 41f tapering, 362, 363f-364f
gagging, 44
masticatory muscle atrophy, 47-48 Dentatus articulator, protrusive interocclusal records for,
nutritional deficiencies, 48-49 339-342
oral cancer, 42
residual ridge resorption, 44-45, 45b Dentist. See Doctor
stomatitis. See Stomatitis Dentition. See also Teeth; specific teeth
traumatic ulcers, 41, 42f
speech adaptation to, 386 adaptive mechanisms, 15
stability of, 389 development of, 14, 14f
surfaces of, 252, 253f, 439f-440f Denture
tissue support for, 12 complete. See Complete denture
tooth-supported, 174-175 dentists’ evaluation of, 400-401
errors in, 402-405
Composite resin posterior denture teeth, 306 existing
Concrete expression, 183
Condyles evaluation and examination of, 84, 502
implant-supported overdenture-related evaluations of, 502
articulator programming for, 294 inadequate, tooth loss secondary to, 260-261
guidance mechanisms for, 337-338 vertical dimension of occlusion determined from
movement of, 269, 284
registering of path of, 337 measurements of, 277, 280f
Coronal reduction of abutment tooth, 169, 171, 175 friends’ evaluation of, 401-402
Counseling, nutrition, 64-68 immediate. See Immediate dentures
Cross-linked polymers, 191 maladaptive behavior, 483-484
Custom impression trays mandibular. See Mandibular denture
immediate dentures maxillary. See Maxillary denture
patients’ evaluation of, 401
sectional, 134-137, 139f-143f patient’s reaction to, 183
single full arch, 133-134, 137f-138f single. See Single dentures
two-tray, 134-137, 139f-143f surfaces of, 252, 253f
maxillary dentures, 223, 225-230 Denture adhesives
components of, 443
D contraindications, 444-445
Data collection and recording techniques cream vs. powder, 445
definition of, 442
description of, 77-78 description of, 442
diagnostic casts, 83 indications, 444-445
intraoral videography, 80 limitations of, 447
measurements, 83 mechanism of action, 443
palpation, 82-83 objective responses to, 443-444
preextraction radiographs, 79 patient education regarding, 445-447
questions, 78 professional attitudes toward, 447
radiography, 80-82, 81f subjective responses to, 443-444
records, 78-79 Denture base
visual observations, 79-80 adhesion, 438
Deflasking, 398 adjustment of, 420-424
Deglutition biomaterials for
description of, 9
occlusion and, 19 cast metal alloys, 205-207, 206b, 206f
reflex, 19 copolymers, 190-191
Dehydration, 58 requirements, 191b
Dental arch resins. See Denture base, resins
anteroposterior position of, 309 titanium, 206-207
description of, 258-259 cured, shaping and polishing of, 398-399
harmony of, 362-364, 363f-364f description of, 13
mandibular, 259-260, 260f, 365 evaluation of, 472
fracture of, 434
ideal, 191b