ORTHODONTIC-Gurkeerat Singh-Textbook of Orthodontics (2007)

Orthognathic Surgery 289

Excess mand ibular bone causes protrusion of the lower
jaw beyond the normal alignment with the upper jaw;
with a resultant Class III malocc1usion. This can
prevent effective biting and chewing of food and
hastens periodontal disease. Temporomandibular joint
function and speech may be impaired. In addition
there may be chin hyperplasia or malposition which
will require correction.

Mandibular Retrognathism (Fig. 25.6) Fig. 25.7: Mandibularasymmetry

This could be as a result of the mandible being too ABNORMALITIES OF THE CHIN
small in all dimensions (micromandibulism) or the
base of the body being positioned posteriorly (retro- The chin should be evaluated separately from the
mandibulism). This deficiency of the mandibular bone mandible. The chin prominence includes both bone
does not allow the upper and lower teeth to come and soft tissue that may require separate surgical
together when chewing food and may affect speech. management. Common abnormalities are:
Sleep may also be impaired due to a retruded or
deficient lower jaw. A deficiency of bone supporting
the chin may require surgery to build up the tissue
and provide a normal framework for the chin.

Macrogenia

The chin is too large in all dimensions. An anteriorly
placed normal sized chin prominence (antegenia) will
give a macrogenic appearance.

Microgenia

The chin is small in all dimensions. A normal sized
chin, placed posteriorly (retrogenia) should be
distinguished from microgen.ia.

Fig. 25.6: Patient withbilateralTMJankylosis ABNORMALITIES OF
THE ALVEOLAR PROCESSES
Mandibular Asymmetry (Fig. 25.7)
The alveolar process abnorma lities should be assessed
The two halves of the base of the mandible have independently of the anomalies of the bases of the
unequal dimensions; this may be seen in patients with mandible and maxilla. The alveolar processes may be
hemimandibular hyperplasia, hemimandibular abnormal either in size, i.e. macro-/micro- or in
hypertrophy. Both halves of the base of the mandible position, i.e. retro-/ ante. In addition they may be either
may have equal dimensions but may be shifted to one too h.igh or too low.
side; this is called lateromandibulism.
Other abnormalities which require surgical correc-
tion include long face and short face syndromes and
open bite (apertognathism).

290 Textbook of Orthodontics

PLANNING ORTHOGNATHIC SURGERY Fig. 25.8: Orthopantomogram of a patient with facial
deformity. Note the difference in the lnter-occlusal
CLINICAL EXAMINATION distance between the right and the left side

Tins should include a general medical examination to
rule out any systemic disorders, e.g, acromegaly. Local
oral examination should include overall dental health.
Any pulpal or periodontal infections should be
eradicated before surgery. The TMJ is assessed for any
pre-existing pathology, e.g. clicking, locking,
tenderness, deviation, etc. Rule out any normal
imbalance specially pituitary.

SOCIO-PSYCHOLOGICAL EVALUATION

Assessment of the patient's awareness of his/her
dentofacial deformity and expectation from treatment
should be done. This helps in determining the patient's
motivation towards surgery. The patient's social status
should also be evaluated.

RADIOLOGICAL EXAMINATION

A complete dental radiographic survey can be done
with an orthopantomogram (OPC) (Fig. 25.8) to rule
out a periapical or periodontal pathological condition.
The X-ray will also aid in the determination of the
stability of teeth in the supporting tissue and their
ability towithstand the stresses of fixation devices and
immobilization. Any impacted/embedded or ectopic
teeth, which may come in the line of the osteotomy
cut, should be preferably extracted 6 months prior to
surgery. The position of the ID canal and the
anteroposterior width of the ramus is assessed when
mandibular ramus osteotomy is planned. The flare of
the rami is assessed on a submentovertex view (Fig.
25.9) when intraoral approach for ramus osteotomy is
planned. If extra or intra-oral approach is to be used.

Photographs Fig. 25.9: Sub-mentovertex view of skull, of a patient with facial
deformity. Note difference in the position of the two mandibular
Preoperative photographs are necessary in order to condyles
have a record of pretreatment profile. Morphometric
measuremen ts can also be done on these photographs. cephalogram (Fig. 25.10) and/or anteroposterior
Frontal and lateral photographs are usually taken in a cephalogram (Fig. 25.1J) (in asymmetry cases) is most
natural head positions. helpful in determining precisely the location of the
deformity and in selecting the proper operative sites
CEPHALOMETRIC EVALUATION for surgical correction. Soft tissue outline on the
cephalogram is marked by painting barium on the
This is essential for preoperative evaluation of all midline of the patient's face prior to shooting the
patients regardless of the type of deformity. Lateral radiograph. A combination of commonly used land-

Orthognathic Surgery 291

marks and measurements determine the degree and
location of dento-skeletal deformity. Legan's Burstone
and cephalometries for orthognathic surgery (COGS
analysis) is also used as it relies on linear rather than
angular measurements, which is helpful in planning
surgery.

Fig. 25.10: Lateralcephalogram, of a patient with STUDY MODELS
facial deformity
Two sets of dental stone models are constructed from
the patient's innpressions. Bite registration is useful
while mounting the models on an articulator. One set
of study models are evaluated for intra-arch, inter-arch
discrepancies and for occlusion. The study models are
invaluable aids when assessing the feasibility of
surgical correction as they provide a permanent three-
dimensional record of the dental and underlying
skeletal structures. They also present the various
permutations of movement area involved that will
need to be explored to correct the presenting facial
and jaw disharmony. A second articulated set is used
as working models on which mock surgery is perfor-
med.

PREDICTION TRACING

The postoperative profile of the patient can be
predicted with some degree of accuracy by cephalo-
metric means. This is called "prediction tracing".
Essentially, after knowing the location and severity of
deformity; the osteotomy and the extent of movement
of the osteotomized segment is determined. On an
acetate tracing of the cephalogram, the osteotomized
segment is cut out and moved as calculated. The soft
tissue follow the movement of bone in a ratio
determined by the type of movement and the
technique performed (Table 25.1). However, these soft
tissue changes are only meant to be a guide for
prediction tracings and are variable. These tissue
changes are marked on the tracing to give the
postoperative profile.

Fig. 25.11: Frontalcephalogram,of a patientwithfacial MODEL SURGERY
deformity
Using prediction tracings; a surgical plan is decided
upon and then the surgery is simulated on articulated
working models. The models are cut and repositioned
in the desirable position and the segments secured in
their new position with sticky wax. The occlusion
achieved is evaluated for stability and any modifi-

292 Textbook of Orthodontics

Table 25.1: Ratio of movement produced in the soft tissue to the movement of the underlying
bone with various surgical procedures

Procedure Technique Bone: soft tissue Ratio 01 movement

Mandibular setback BSSO Pogonion: Soft tissue chin 1:1
BSSO Pa tient B: Inferior labial sulcus 1:0.9
BSSO Lower incisor: Lower lip 1: 0.8
BSSO Pogonion: Superior labial sulcus 5:1

Mandibular advancement BSSO Pogonion: Soft tissue chin 1:1
BSSO Lower incisor: Lower lip 1:0,75
BSSO + Sliding genioplasty Pogonion: Soft tissue chin 3:2

Genioplasty (augmentation) Pogonion: Soft tissue chin 4:3

Genioplasty (reduction) Pogonion: Soft tissue chin 5:4

Maxillary advancement Le-Port! Upper incisor: Upper lip 2:1

Le-Fort I ANS: Nasal tip 7:2

Premaxillary setback Wassmund Upper incisor: Upper lip 3:2

Wassmund Upper incisor: Lower lip 3:1

cations required noted. Splints are then constructed a combination of movements is required in either one

which are of immense help during surgery. or both jaws.

PROCEDURES ANTEROPOSTERIOR CORRECTION

Tn orthognathic surgery, a bone cut (osteotomy) is Maxillary Surgery
made in the affected jaw, and the bones are reposi-
tioned in a more normal alignment. Generally, the Advancement Le-Fort J (Figs 25.l2A to F) down-
bones are held in their new positions with plates, fracture and advancement is the preferred technique
screws and wires. The patient may also need arch bars for maxillary retrognathism. The length of the vascular
placed on both jaws to add stability. It is usually pedicle and soft tissue compliance limits the extent of
performed under general anesthesia as an inpatient anterior movement.
procedure. In some cases, adjunctive procedures such
as a reconstructive rhinoplasty, malar augmentation, Retraction Retraction of a Le-Fort 1segment is difficult
genioplasty and bone grafting procedures are needed because of the presence of the pterygomandibular
to correct deformities associated with malformation plates and tuberosity. Therefore anterior segmental
syndromes. Patients with deficient bone tissue may osteotomy (Wassmund (Figs 25.13A to C) or
require grafts from their ribs, hips or skull. Alloplastic Wunderer procedure or Cupar/s technique) after
replacement of missing bone may also be required. extraction of a premolar on either side is most
commonly performed in maxillary prognathism cases.
Both jaws can be osteotomized and repositioned
in all the three planes of space, i.e. anteroposterior, Mandibular Surgery
vertical and transverse in order to achieve a balanced
profile and occlusion. Needless to say that commonly Advancement Bilateral sagittal split osteotomy (BSSO)
(Figs 25.14 and 25.15) is currently the most preferred
technique since it can be performed easily intraorally.

Orthognathic Surgery 293

Fig. 25.130: Pre and post-treatment photographs of a case
treated with upper first premolar extraction and anterior maxillary
subapical set-back

Figs 25.12A to F: Le-Fort I osteotomy for maxillary
repositioning

Figs 25.13A to C: Wassmund's procedure Figs 25.14A to F: Sagittal split technique for mandibular
setback or advancement

Inverted L osteotomy and C-osteotomy (Figs 25.16A advancement of the mandible. The former can be
to D) are also procedures performed in the ramus for performed intraorally whereas the C-osteotomy is

Textbook of Orthodontics

Fig. 25.15: Mandibularadvancement using the bilateral Fig_25.17: Bilateralsagittalsplitosteotomy(6880)
sagittal splitosteotomy (B880) technique used for achievinga mandibularsetback

movement of the dentoalveolar segment can be perfor-
med in case of mandibular excess with chin deficiency.

VERTICAL CORRECTION

Maxillary Surgery

Both superior positioning (for long face correction)
(Fig. 25.18) and inferior positioning (for short face
correction) can be performed by Le-Fort I down-frac-
ture technique. Inferior movements however is less
stable and usually require insertion of bone graft or
hydroxyapatite blocks between the segments in order
to increase stability. Simultaneous ramus osteotomy
is helpful in preventing relapse.

Mandibular Surgery

Figs 25.16A to D: (A) Normalrelations,(B)Verticalsubsigmoid Shortening of vertically excessive mandible should be
done by inferior border osteotomy and chin
osteotomy (C) Inverted L osteotomy, (D) C-osteotomy of augmentation horizonta lly, Elongation of lower facial
mandible

done extraorally. Anterior segmental subapical
osteotomy can be performed if only the alveolar
segment needs to be advanced without moving the
chin-point.

Setback Bilateral sagittal split osteotomy (BssO) (Fig. Fig. 25.18: Pre- and post-treatment photographs after
25.17) or transora Ivertica 1 or oblique ramus osteotomy Le-FortIdownfractureand superiorrepositioningofthe maxilla
are usually performed for this movement. If closure
of bilateral edentulous spaces or a narrowing of the
arch is required, then a body ostectoniv is performed
where a segment of full-thickness bone is removed.
Anterior segmental subapical osteotomy and posterior

Orthognathic Surgery 295

height can be done with BSSO, which rotates the allograft. Genioplasty is done to improve results of
mandible down and forward. mandibular advancement or reduction or to correct
asymmetry.
TRANSVERSE CORRECTION
MALAR AUGMENTATION
Maxillary Surgery
This is done through the mouth and can give added
Expansion of maxillary arch is usually performed in height and fullness to the cheeks. An allograft is
conjunction with Le-Fort I down-fracture in which normally inserted after taking impression of face and
parasagillal osteotomies immediately medial or lateral making a face model into a pocket of soft tissue
to the nasal wall with an extension going between the through an incision in the buccal vestibule which is
roots of central incisors is carried out. Bone graft is stabilized with the help of suture, screw or wire.
needed to fill the space created by lateral movement
of the posterior segments. If constriction of the arch is Patients with deficient bone or soft tissues of the
required, bone is removed from the osteotomy sites face may require distraction osteogenesis. A distrac-
as determined by pre-surgical planning, tion device is applied. Bone osteotomies are perfor-
med. The distraction device is then used to slowly
Mandibular Surgery apply a distractive force at the osteotomy site until
new bone is formed. Once the desired reconstruction
Because of the TMJs transverse corrections are diffi- is achieved, the device is left in place until the bone is
cult in mandible. Anteriorly, extraction of a tooth and healed and then the device is removed. This enables a
ostectomy can be performed to achieve constriction surgeon to elongate a facial bone and the adjacent soft
of the arch. Expansion is better done by distraction tissue envelope.
osteogenesis rather than osteotomy.

SKELETAL OPEN-BITE FURTHER READING
CORRECTION (APERTOGNATHIA)
1. BellWH, Fonseca RJ, Kennedy jW, et al. Bonehealing
Skeletal open-bite is a difficult problem to treat, thus after posterior maxillary osteotomy, 1 Oral Surg
a separate mention is being made. Skeletal open-bite
commonly occurs in long-face individuals who have 1971;29:313-22.
vertical maxillary excess, anteroposteriorly deficient
mandible with short ramus height. Lower anterior 2. Bell WHo Le Forte 1 osteotomy for correction of maxillary
teeth may be over-erupted. Le-Fort I down-fracture deformities,J Oral Surg 1975;33:412-26.
and superior repositioning of the maxilla especially
posteriorly best treat these patients. The mandible 3. Edler RJ. Problems in orthodontic management of
autorotates upward and forward, which brings the orthognathiccases,Eur J Ortho 1990;12:420-37.
chin anteriorly. If further anterior placement of the
chin is desired, an augmentation genioplasty is 4. Epker BN, Stell JP, Fish Le. Dentofacial deformties:
performed. Tflower teeth interfere with occlusion, they integrated orthodontic and surgical correction, ed 2, St
can be intruded urthodontically or anterior segmental Louis,1998, Mosby.
surgery can be performed to depress this segment.
5. Gregoret J, Tuber E. Orthodontics and Orthognathic
GENIOPLASTY Surgery Diagnosis and Planning, Barcelona: Espaxs, 1997.

The chin can be moved in all three planes after osteo- 6. Priffit WR, White RP. Surgical-orthodontic treatment,
tomy or may be augmented by an onlay autograft or 1991. Mosby Year Book,Missouri.

7. Profflt WR, Epker BN. In Bell, et al (editors), Surgical
correction of dcntofaclal deformities, 1980, Saunders,
Philadelphia.

8. Vanarsdall RL, Corn H. Soft tissue management of labially
positionedunerupted teeth.AmJ Orthod 177;72(1):53-64.

9. Von der Heydt K. The surgical uncovering and
orthodontic positioning of unerupted maxillary canines.
JAm Orthod 1975;68(3):256-76.

• What are dental implants? Implants to
Mini-Screws
• History
• Types of dental implants Abhay Lamba, Gurkeerat Singh

• Biomaterials for dental implants
• Indications for dental implants
• Orthodontic anchorage

WHAT ARE DENTAL IMPLANTS? had a mediocre success. This was the first implant
design that differed from the root form design.
DEFINITION
Stork in 1938, introduced surgical cobalt chromium
"A dental implant is a biomedical device, which is usually molybdenum alloy implant that he used to replace a
composed of an inert metal or metallic alloy, which is placed left maxillary central incisor and it lasted for 15 years.
on or within the osseous tissues." In 1946, Stork designed a two-stage screw implant,
which was inserted without a premucosal post and
Implants are now being used in orthodontics for later after bone healing took place, the crown and
the purpose of augmenting anchorage. abutment were attached to it. This interface between
bone and implant was called ankylosis and it can be
HISTORY equated with the clinical term as rigid fixation. Rigid
fixation defines the clinical aspect of this microscopic
The history of implants or implant-like devices bone contact with an implant and in the absence of
attached to prosthesis can be traced to ancient mobility with a Ita 500 gm force applied in a vertical
civilizations like Egyptians (2000 years), Ancient or horizontal direction. The first submerged implant
Chinese (4000 years), lncas (1500 years), etc. Different placed by Stork lasted for more than 50 years. Bone
materials were implanted in place of missing teeth; fused to titanium was first reported and documented
ranging from teeth taken from slaves, prisoners, or by Bathe et al in 1940.
from animals. In Tnca skulls, researchers found
precious stones implanted in the jaws to replace In 1952, Branemark started extensive experimental
missing teeth. In Pre-Columbian skulls, they found clinical studies on microscopic microcirculation in
carved stones replacing missing teeth. Arabian bone marrow healing. The lO-year studies regarding
surgeons used ox bone to replace missing teeth. implant placement in the jawbone of the dogs started
in 1960 and in humans these started in 1965 and were
In recent time Maggio/i in 1809, used root-shaped reported in 1977 that led to the term osseointegration.
gold pieces. In the year 1887, Harris and Berry Osseointegra lion was defined as "the contact established
reportedly used teeth made of ceramic or porcelain between normal and remodeled bone and an implant surface
into which lead-coated platinum posts were fitted. In toithou t the interposition of non-bone or connective tissue,"
the early 1900s, Lambotle fabricated implants made of or "direct structural and functional connection between
aluminium, gold, silver, brass, copper, steel, ordered, living bone and the surface of a load-carrying
magnesium, plated with nickel and gold. Greenjield implant." Osseointegration can also be defined as a
in 1909, designed a lattice-cage type implants made direct interaction of bone to an implant surface. As a
of iridoplalinum. It used to be placed surgically and

Implants to Mini-Screws 297

result, the implant fixture is immubilized in the bone d. According ID stages of surgery
and lends itself to function as an anchor for • Single stage
orthodontic anchorage. • Two stage

e. According to implant abutment interface design
• Internal
TYPES OF DENTAL IMPLANTS • External

Dental implants can be subdivided into three major Blade Form
types based on their mode of attachment to the bone
structure as: end o-osseous, subperiosteal and • First introduced by Linkow in 1967
transosseous. • Flat and taper from shoulder towards the base
• Numerous holes for interlocking (retention)
ENDO-OSSEOUS IMPLANTS • Cut a groove and tap into the bone
• indicated for thin alveolar ridges
These implants are screwed, tapped or drilled directly
into the bone. They osseo integrate with the bone. Ramus Frame
These implants provide better initial stability /
retention. A minimum healing period of 3-4 months Metallic markers
is required before they can be loaded. Used in orthodontics and growth studies.

These are available in many designs depending SUBPERIOSTEAL IMPLANTS
upon the bone condition and the type of abutment to
be used. Due to the limited amount of space available, Mainly used in completely edentulous jaw conditions:
high cost and long waiting period for them to osseo- 1. Unilateral
integrate before loading other solutions were 2. Complete
proposed.

TRANS-OSSEOUSIMPLANTS

Root Form-(Also Used in Orthodontics) These are used in certain edentulous conditions and
require major surgical procedures.
a. According 10 the shape 1. Staple
• Straight/cylinders 2. Staple pins
• Tapered 3. Multiple pins
• Stepped
BIOS IMPLANT SYSTEM
b. According to surface fir/ish (BIO-RESORBABLE IMPLANT SYSTEM)

• Smooth Biodegradable polylactide with a metal
• Threaded super-structure.
• Rough
MICRO/MINI IMPLANTS
- Sand blasted
- Acid etched Bicortical titanium screws (most frequently used in
orthodontics)
• Coated
- Titanium plasma sprayed with BIOMATERIALS FOR DENTAL IMPLANTS
- Hydroxyapatite
- Aluminium oxide There are many biocompatible materials available
today but the main emphasis is on metals, metal
c. Combination alloys, ceramics, polymers, composites and carbons.
• Straight smooth
• Straight threaded (screw) METALS AND METAL ALLOYS
• Tapered threaded (screw)
• Stepped-tapered threaded (screw) • Titanium
• Stepped cylinder • Tantalum
• Combination of root form implants
different surface coatings and design

298 Textbook of Orthodontics

• Alloys of titanjum/aluminium/van~dium Table 26.1: Indications for dental implants
• Cobalt/chromium/molybdenum
• Chromium/iron/nickel Indications
• Titanium and its alloys are most widely used. 1. Edentulous mandible
2. Edentulous maxilla
CERAMICS AND CARBONS and sapphire) 3. Frontal region upper jaw
4. Partially edentulous jaws (one or two missing teeth)
• Aluminium oxide (aluminium
ceramics • Kennedy's class rr and m
5. Single tooth implantation
• Carbon 6. Extraoral implantation, (epithesis)
• Carbon silicon compounds.
7. Immediate implantation
POLYMERS AND COMPOSITES • Trauma (bone situation is to be considered)
• Periodontal problems
• Polymethylmethacrylate • Periapical pathology, and resorption of roots
• Silicon rubber • Agenetic elements, (by birth missing teeth)
• Polyethylene • Caries
• Polylactide
8. Orthodontic anchorage

Table 26.2: Contraindications tor dental implant placement

INDICATIONS FOR DENTAL IMPLANTS Contra indications
1. Medical
Dental implants were mainly developed for the
replacement of missing teeth. The high rate of success • Temporal (flu, pregnancy, etc.)
achieved with osseo integrated (fused with jaw bone)
dental implants allowed patients to enjoy the benefits • (Auto) immune diseases
of fixed rather than removable restorations/
prosthesis. The main indications for implants • Terminal illness
restoration in the partially edentulous patients-with
free end distal extension (no back teeth available for • Inability to restore with prosthesis
support) where no posterior abutment is available and
the long edentulous span is present. In both these Usc of corticostcroids
situations, the conventional dental treatment plan
would include a removable partial denture. However, • Radiotherapy of the head, (turnoricldal radiation
with the advent of implant abutments, the patient can of implant site)
benefit from fixed resto-rations. Additionally, in short
edentulous span (missing teeth); the single implant is • Severe Diabetes mellitus
becoming a more popular option.
• Psychological problems (unrealistic patient
The indications for implants are many and varied
(Table 26.1). Further research and technical expectation)
advancement in the field of implant placement has
permitted the use of implants in other allied fields, 2. Dell tal
such as orthodontics, where implants are used as
anchorage units. The increased demand for Anatomy-nerves (too close), sinus, etc.
orthodontic treatment by adult patients and the
importance of not loosing anchorage has fueled • Local pathology-cyst, roots stumps,
extensive research on the topic. Still care must be taken
so as not to be overzealous with implant placements gum problems, etc.
and due considerations should be given to the
conditions which may contraindicate their use (Table • Microbiology-bacterial sensitive.

26.2). • Bad Oral hygiene

Lack of operator expertise

• Motivation
• Non cooperative patient

3. Genera!

Finance

• Touring job (unable to keep appointments)

• Attitude
Spastic patient

ORTHODONTIC ANCHORAGE

With the advent of prosthetic implants and their
predictable results, the orthodontists saw an
opportunity to use them for the purpose of anchorage.
Routinely used dental implants are unsuitable for use
as orthodontic anchorage units as their size precludes

Implants to Mini-Screws 299

their use, unless edentulous regions exist in the mouth. f'
Initially routine dental implants of relatively lesser
diameter 3.5-4.5 mm and varying lengths (10-16 i ,i
mm)were used in orthodontics. They were of the self-
tapping variety with the threads having a sandblasted .T" i f
or acid-etch surface finish. The polished trans-mucosal
neck was either 2.5 or 4.5 mm long. Because of their Fig. 26.2: Commerciallyavailable mini-implants(A) TOMAS
size they were generally placed in the palate or in the Dentaurum (Germany), (B) Bredent (Germany), (C) Dentos
retromolar region (Fig. 26.1). (Korea)

Following their success, implants were especially difficult conditions (Table 26.4). The "mini-implants"
designed for anchorage in orthodontics (Fig. 26.2). have the advantage of being practically immovable
They are smaller in diameter generally 0.9-1.6 mm in when used for the purpose of exerting tooth moving
diameter and ranged from 6-12 mm in length. The forces. This ability of providing absolute anchorage
implant head has a hole and / or a groove to accept helps in achieving difficult movements like molar
an orthodontic wire or other orthodontic accessories. distalization (Fig. 26.4A), enmass retraction (Fig.
They can be of the self-tapping or the self-drilling 26.4B), etc routinely. This in turn is responsible for
variety (Table 26.3) decrease in size has also led to the increased acceptance of orthodontic treatment by
their being placed rather easily in other sites like in adults and other esthetically conscious patients, as
the interdental region, between the molars (Figs 26.3A segmental treatment becomes possible (Figs 26.4C and
and 26.38). Their small size has led to them being 26.4D). They are capable of providing excellent
called-"mini-implants, micro-implants, mini-screws anchorage for a relatively minor increase in the cost
or mini-pins". Five main systems are available and of orthodontic treatment, also decreasing treatment
the rest nee derivatives of the same- time.

• SAS systems, Sendai Japan Implants have been used to distalize maxillary and
• OMAS Systems, Taipei Taiwan, Lomas-Mondial, mandibular molars and groups ofteeth, and to obtain
tipping, uprighting, intrusion, extrusion and transfer
Germany
• ORLUS Systems, Yonsei University, Seoul, Korea
• Mia Systems, Kyungpook University, Daedu,

Korea
• TOMAS, Dentaurum, Germany

Orthodontic implants are now gaining in
popularity for their ability to provide anchorage in

Fig. 26.1: Palatal implantused to stabilizethe maxillary
canines. whichare use to distilizethe maxillarymolars

300 Textbook of Orthodontics

Table 26.3: Micro-implant surgical procedures

• Direct method the implant
To place mini-implant directly without an Incision
Indicated in placements over 'attached gingiva'

In majority of the cases
More predictable results
• Indirect Method
Placements over 'unattached gjngtva'

Will require a vertical incision of 2 tu 5 mm in length.
Relatively less commonly used
The implant will be covered by the gingival tissue
Micro-implant Driving Methods
• Self Tapping and
• Self Drilling
Self Tapping
• Pre-Dnlling with a suitable drill 0.2 mm less than that of the mini implant to be implanted
Self-Drillillg
• No need to pre-drill
• Just use a round bur or a small 2 to 4 mm drill to get a 'purchase point', especially when angulating
Surgical Procedure for Self Drilling

Step T-isolate the region and -exposed bone would cause the
apply surface anesthct!c (15% bleeding puint to be visible
Lidocanine)

Step Il-anesthetize using Step V-under copious irrigation
infiltration 0.2 ml anesthetic make pilot hole (using a round burr
or drill-2to 4 mm in length) through
the cortical bone (optional but
preferable)

Step ID-mark the exact location Step VI-using the edeptcr/screw
using the periodontal probe. driver provided screw the mini-
implant into the bone, or USe an
implant' physio-dispenser.

-c-mini-implant after placement.

Step lV-using the tissue punch Surgical procedure for removal of
expose the bone mini-implant

Since the mini-implant does not
osteo-intigrate the mini-implant can
be easily unscrewed using the screw
driver provided. It leaves small
bleeding point which heels without
any medication or suturing required

Implants to Mini-Screws 301

Table 26.4: Contraindications for dental implant placement Fig. Zti.4A; Distilization of the maxillary posterior segment
using a mini-Implant
a, General contra-indications:
The microimplant must not be used if the patient has-
1. History of immune deficiency,
2. History of steroid therapy <in the past 6 months),
3. Bleeding or clotting disorders,
4. Uncontrolled endocrine disease,
5. Bone disease,
6. Rheumatic ailments,

7. Cirrhosis of the liver, or any other acute disease.
b. Local contra-indications:

1, The osteomyelitis of the jaws,
2. Receives radiation therapy in the head and nee

region,
3. H:1sreceding gingtva! disease or
4. Uns;ttisfJctory oral hygiene.

of anchorage to other parts of the mouth. The implants resulting in a favorabie trans!atory tooth movement
and the new bicortical titanium screws are so (Fig. 26.5). The implant assisted orthodontic treatment
convenient to place that the line of action of the helps to minimize anchorage loss and decrease the
orthodontic force can be made to coincide with the overall duration of treatment, as these can be loaded
level of the center of resistance of the teeth to be moved immediately. Headgears and other extra-oral means

Textbook of Orthodontics

Fig. 26.48: Enmass retraction in a critical anchorage case

Fig. 26.4C; Segmental treatment used to align an impacted maxillarycanine

Fig. 26.40; Segmental treatment used to intrudethe Fig. 26.5; Enmass retraction of maxillaryand mandibular
mandibular incisors
incisorswiththe pointofapplicationofforcecloserto the csntsr
of resistance of the teeth to be retracted

of anchorage are eliminated. Most importantly, their use especially when treating young individuals
orthodontic treatment is now possible in cases where below the age of 14 years, because young patients
multiple teeth are missing (Fig.26.6) or the other have more spongy bone which at times doesn't allow
anchorage units are compromised. Also, trea tment is the primary stability to be achieved at the time of
no longer dependent on patient cooperation. initial placement.

There are few contraindications to the use of rnini- Mini-screws can be placed at various sites (Table
screws (Table 26.5) but it is advised to be cautious in 26.6) to either provide direct or indirect anchorage.

Implants to Mini-Screws 303

Fig. 26.6: Implant placed in the endentulous region to retract Table 26.6: Uses of implants in orthodontics
the remaining teeth in the arch
Orthodontic anchorage
Table 26.5: Various sites for micro-implants Used for retraction of anterior teeth,
Up righting of molars.
Various Sites of implants Mesiodistal tooth movement,
• Maxilla Open bite correction (archived by intruding posterior
teeth: skeletal anchorage)
- Tnfrazygomatic crest area. Distalization of 1st and 2nd molars
- Maxillary tuberosity area Intrusion of teeth
- Intra radicular between the roots both buccally and Compromised anchorage in period on tally involved
teeth where anchorage is a problem/congenital
palatally anomalies and developmental defects of jaws which
- Mid palatine area may result in inadequate anchorage.
• Mandible Replacement of missing teeth after the completion of
- Retro molar area orthodontic treatment (should be done only after
- Intra radicular area completion of craniofacial growth)

Mandibular symphysis
• Others

- Edentulous areas

Direct anchorage potential is said to be used when Fig. 26.7A: Direct anchorage to mesialize the molar
the forces are afflicted directly from the screw head

(Fig.26.7A) ego E-chains used to retract teeth. Indirect
anchorage is said to exist when the mini -screw is used

to immobilize or augment tile anchorage potential of
the molars (Fig. 26.78).

Fig. 26.78: Indirect anchorage

304 Textbook of Orthodontics

Mini-screws are likely to revolutionize the way 6. Maino HS, Kyung HM, Sung J. A simple method of molar
orthodontic treatment is planned and executed with uprighting with micro-implant anchorage. J Clin Orthod
anchorage planning having become simplified and 2002;36:592-96.
treatment time decreasing, more and more patients
are likely ot become motivated to seek orthodontic 7. Paik CH, Woo Y], Kim J, Park JU. Use of mini screws for
treatment.
inter maxillary fixation of lingual orthodontic surgical
FURTHER READING
patients. J Clin Orthod 2002;36:132-36.
1. Bae SM, Park HS, Kyung HM, Kwon OW, Sung JH. 8. Park H, Bae S, Kyung H, Sung I. Micro-implant anchorage
Clinical Application of Micro-implant anchorage
2002;36:298-302. for treatment of skeletal Class Tbialvcolar protrusion. J
Clin Orthod 2001;35:417-22.
2. Costa A, Raffaini M, Melson B. :Miniscrew as orthodontic 9. Park HS, Kyung HM, Sung JR. A simple method of molar
anchorage: a preliminary report, Int J Adult Orthod uprighting with micro-implant anchorage, J Clin Orthod
Orthognath Surg 1998;13:201-09. 2002;36(10):592-96.

3. Gainsforth BL. A study of orthodontic anchorage 10. Roberts WE, Nelson CL, Goodacre Cl. Rigid implant
possibilities in basal bone. Am J Orthod Oral Surg anchorage to close a mandibular first molar extraction site,
1945;31:406-417. J Clin Orthod 1994;28:693-704.

4. Kanomi R. Mini-implant for Orthodontic Anchorage. J 11. Umemori M, Sugawara J, Nagasaka H, Kawamura H.
Clin Orthod 1997;31:763-67. Skeletal anchorage system for open-bite correction. Am J
orthop 1999;115:166-74.
5. Lee JS, Park HS, Kyung HM. Micro-implant anchorage
for Lingual Treatment of a skeletal Class IT Malocclusion. 12. Wehrbein H, Glatzmaier), Mundwiller U, Diedrich P. The
J Clin Orthod 2001;35:643-47.
orthosystem: A new implant system for orthodontic
anchorage in the palate. J Orofac Orthop 1996;57:143-53.

Genetics in
Orthodontics

Gurkeerat Slngh

• Introduction • Inbreeding and consanguineous marriages-
• Mode of transmission of malocclusion its consequences
• Tracing the gene in familypedigree studies
• Penetrance and expressivity • Dental and skeletal characteristics that are
inherited

INTRODUCTION REPETITIVE TRAITS

Genetics, is the science of the study of genes. It is a The recurrence of a single dentofacial deviation within
vast field with practically unlimited potential. The only the immediate family and in the progenitors. The same
thing that most people associate this science with is trait is seen generation after generation.
Gregor Mendel, the fathcr of modem genetics, and his
law of segregation. Lately the cloning of sheep and DISCONTINUES TRAITS
proposed cloning of humans have again brought it in
the news. But why should a student of orthodontics The recurrence of a tendency for a malocclusal trait to
be interested in genetics? The reason is very simple, reappear within the family background over several
what ever affects the growth, development and generations. The trait is seen in the family but not in
function of the oral and facial structures is of interest all generations.
to the student of orthodontics. We have to know
exactly why or how a malocclusion occurs, to what VARIABLE TRAITS
extent does it express in the next generation, what is
its prevalence and how will it react to a certain The occurrence of different but related types of
treatment plan. And, most importantly, if it can be malocclusion within several generations of the same
prevented. family. These traits are seen with a variable expression
for example, missing teeth, which arc commonly seen
Genetics sheds light on all these questions. It helps feature in some families, but the same teeth may not
us to segregate the genetic or inherited malocclusions be missing in different generations and/ or within the
or aberrations of growth from those due to the effect same generation.
of environmental factors. Thus, it helps us diagnose,
treat and subsequently maybe prevent it from For an anomaly to be considered of hereditary
occurring in the next generation. origin, it should occur and be a well-defined variation
in family groups. A diagnosis of genetic malocclusion
MODE OF TRANSMISSION OF MALOCCLUSION should not be made on the basis of a single case of
recurrence in the family. Longitudinal studies of
There are three types of transmission of malocclusion pedigree same family are a great help in recognizing
from the standpoint of genetics. and quantifying such malocclusions.

Dobzhansky realized the role of the environment
when he stated that, "the individual never fully

306 Textbook of Orthodontics

realizes the genetic pattern in postnatal life. Human AUTOSOMAL RECESSIVE INHERITANCE
potentialities are determined by the genotype, but their
manifestation depends on environment". He was of Abnormal recessive genes are transmitted through
the opinion that, growth pattern possesses a gene- heterozygotes. Their existence is found out only when
tically determined plasticity which makes it possible two heterozygotes marry and the homozygote
for environmental conditions to influence it. appears.

According to Neel, genetic factors were entirely or Characteristics of autosomal recessive inheritance
largely responsible for not more than 20 percent of all are:
malformations; chromosomal defects (un-inherited but 1. The trait is visible only in siblings, but not in their
heritable) account for about 10 percent of all
malocclusions. parents or other relatives.
2. The parents of an affected person may have been
Evidence of genes being responsible for a particular
characteristic in the production of an anomaly can be blood relatives (consanguineous).
frequently masked by environmental conditions such 3. About one-fourth of the children of such parents
as climate, economic conditions, oral hygiene, the
quality of dental care available during the formative are affected; the recurrence risk at each birth is 25
years, and other variables. According to Neel, majority, percent.
nearly 60 percent, of all malocclusions are caused due 4. Both male and female children have equal chance
to environmental factors. of being affected.

Acquired characteristics are not genetically SEX-LINKED RECESSIVE INHERITANCE
transmissible. However the genes are subject to
mutation. Knowledge of human inheritance is possible This type of inheritance is mostly X-linked and predo-
only from the study of pedigrees and not on minantly males are affected (due to their hemizygous
experimentation and actual crossbreeding as in condition). Heterozygous females are carriers and are
animals. expected to produce affected and normal sons in the
ratio of 1.1. An affected male never produces an
affected son, for example hernophilia.

TRACING THE GENE IN Characteristics of
FAMILY PEDIGREE STUDIES X-linked Recessive Inheritance

The inheritance of a particular gene has to be studied 1. Males are affected more frequently than females
over several generations of a family to be able to 2. When the female parent is carrying the trait then
pinpoint its characteristics and isolate the influence of
environmental factors. 50 percent of her sons have a chance of being affec-
ted, and 50 percent of the daughters would be
AUTOSOMAL DOMINANT INHERITANCE carriers but ph enatypically normal.
3. The trait can be transmitted through several
Characteristics of autosomal dominant inheritance are: generations by carrier females.
1. The trait appears in every generation. 4. The affected male parent cannot transmit the trait
2. An affected child must have at least one affected directly to his sons, i.e. the trait wil.lskip a gene-
ration.
parent.
3. Abou t one half of the offspring of an affected Sex-linked Dominant Inheritance

person are affected; the recurrence risk is 50percent Characteristics of X-linked dominant inheritance are-
at each conception. 1. The affected male parent transmits the trait to all
4. Both male and female persons are affected.
5. The characteristic is not transmitted in the progeny his daughters but not to the sons.
of the unaffected individuals. 2. When affected females are homozygous, they

transmit the trait to all their children irrespective
of thei r sex.

Genetics in Orthodontics 307

3. When affected females are heterozygous, only 50 inbreeding causes an increase in the frequency of
percent of their children of both sexes ha ve a chance homozygotes among the offspring. Recessive
of being affected. phenotypes appear with grf'ater frequency among the
progeny of inbred matings than in the general
4. Affected females transmit the trait to their progeny population.
in a manner similar to that in autosomal dominant
inheritance. Many researchers have contended that racial
admixture increases the occurrence of malocclusion.
POLYGENIC DISORDERS AND The contention is not without its distractors yet it is
MULTIFACTORIAL INHERITANCE established that the occurrence of malocclusion and
cleft lip and palate is more in offspring's of consan-
The polygenes have small additive effects. The clinical guineous marriages.
features are due to cumulative effects of all the
polygenes as well as other factors. These other factors DENTAL AND SKELETAL CHARACTERISTICS
may be certain other genes that have not been
identified or local or general environmental factors. THAT ARE INHERITED
The term multifactorial inheritance is now preferred,
as it gives a more precise meaning-multiple factors Salzmann enumerated the malocclusions of genetic
associated with the inheritance of the trait. Cleft lip origin (Table27.1).Since then various other parameters
and/or palate is a classic example of such type of have been studied and are included in the following
inheritance. discussion. It is being repeatedly stressed that,
developmental hereditary characterietics are influenced by
PENETRANCE AND EXPRESSIVITY local or general environmental factors and their penetrance
and expressivity can be greatly modified by these influences.
These terms are used to describe variable gene expres-
sion. Penetrance is the proportion of individuals that show Occlusal variations are polygenic, Le.controlled by
an expected phenotype. When a gene is completely both, many genes and various environmental influ-
penetrant it is always expressed; when incompletely ences. Extreme deviations are generally due to
penetrant, the gene is expressed in some individuals, chromosomal or single gene defects.
not in others, the proportions depending upon the
degree of penetrance. Expressivity is the degree to which Stockard's studies on the crossbreed ing of pure-
a gene is expressed in the same or in different individuals. bred dogs suggest that one set of genes predetermines
A genetic variation may produce peg laterals, or the structural pattern of the maxilla, and other of the
absence of lateral incisors or absence of one lateral mandible. It can hence be assumed that growth of the
incisor and a peg-shaped lateral on the contralateral two jaws is independent of one another.
side.
Class IT and Class III malocclusions have a poly-
INBREEDING AND CONSANGUINEOUS genic mode of inheritance, i.e. they are influenced by
MARRIAGES-ITS CONSEQUENCES the action of many genes and environmental effects.
Redman and Shapiro proposed that genes on X-
Inbreeding is defined as mating between close relatives. chromosome cause a lengthening of the mandible
Consanguineous individuals have at least one not-too- relative to the maxilla. This has been eo-repeated by
remote ancestor in common. the studies of Horowitz and Morishima, who found a
very high percentage of Class II relationships in XO
The main genetic consequence of inbreeding is an (Turner's syndrome) subjects. However, Litton, et al
increase in the proportion of homozygotes. Through and Bookrnan, et a/ found no evidence of sex linkage
inbreeding, recessive genes are more easily brought in their studies of Class 111 malocclusion. But resear-
to the fore and are thus expressed. Stud ies involving chers have found strong eo-relation when studying
such individuals help researchers to obtain an estimate the "Haspsburg Jaw" and in some eastern Aleut
of the amount of hidden genetic variation. families (here the trait is considered due to a single
chromosomal or gene defect).
Consanguinity can cause unmasking a hidden
recessive gene. Mating between relatives, or Genetic variation has a major effect on arch width
and length. A genetic contribution to arch shape (the
maxillary being greater than the mandibular) was

308 Textbook of Orthodontics

found by Richards, et al. The reverse is true for the Table 27.1: Malocclusionof genelicorigininclude
over all size of the jaws, with effect being greater on
the mandible. Significant genetic variance has been 1. Prognathism
reported for dental arch and palate dimensions, but 2. Extreme micromandlbular development
environmental influences seem more important for 3. Bimaxillary protrusion
occlusa I traits. 4. Bimaxillary atresia (small mouth and underdeveloped

Chug, et at and Schull and Neel separately studied arches)
inbreeding effects in Japanese children and reported 5. Teeth of extraordinarily large size and abnormally small
an increased occurrence of malocclusion in the offs-
pring of consanguineous marriages. Investigators have jaws, or vice versa
also suggested an increased occurrence of mal- 6. Hypoplasia and discoloration of teeth
occlusion due to racial admixture. 7. Abnormalities of the number and arrangement of the

Separate studies done in Hawaii and Sweden teeth
concluded that the degree of genetic determination 8. Facialclefts;cleftlip and cleftpalate
9. Ectodermal dysplasia--craniofacial dysostosis
was greatest for the width of the upper central incisors 10. Characteristic crowding of the teeth with rotation and
and decreased in order for object overbite, and the
sagittal molar relationship. ectopic position of certain teeth, notably the maxillary
canines in cases where deciduous teeth have not been
Genetic determination of maxillary and mandibular exfoliatedtoo early
dentition has been found to be independent of each 11. High palate associated with extremely narrow face and
other. Wider ranges of genetic factors have been found head
to influence the mandibular rather than the maxillary 12. The pattern of the tooth crowns, roots, presence of
teeth. Crown dimensions are largely under genetic Carabclli's cusps and pits and fissures of the teeth,
control. shovel-shaped incisors, enamel extensions and
taurodontism can be attributed to heredity. according to
Corrucciru, et at have reported variable and Kraus
frequently insignificant genetic variance for overbite, 13, Upperfaceheight,noseheight,headheightandbigonial
overjet, sagittal molar relationship, posterior cross-bite, width show the greatest genetically determined variation
and rotations of anterior teeth.
frequency of Class IT and low frequency of Class In
occlusion in North American Caucasian and European
populations and the reverse situation (high frequency

BUTLER'S FIELD THEORY of Class 1lI,low frequency of Class III in some groups
of Asian origin, including Polynesians, Alaskan
Butler divided the mammalian dentition into several Eskimos, Aleuts, American Indians, and Pacific
developmental fields. For example in humans,- the islanders in general. Grewe et at reported that the
molar / premolar field, the canine field and the incisor tendency towards Class II relationships in North
field. According to his theory, among the fields the American Indians increased in relation to the propor-
maximum variability manifests itself in the distal and tion of Caucasian ancestry; Baume has observed a
the least in the mesial direction. Hence, maximum similar effect in Polynesian-Caucasian hybrids.
variability will be seen for the third molars or the
lateral incisors as compared to the first molars or the These observations strongly suggest the presence
central Incisors respectively. of quantifiable genetic variation in the sagittal molar
relationship among human populations.
As an overview it would suffice to say that even
though the jaw size and shape are under genetic Long-term evolutionary changes in the dentofacial
control, they show wide variation due to the influences complex apparently have involved a reduction in jaw
of local and general environmental factors. The tooth size in association with the needs of cepha lization and
shape, number and size anomalies are genetically upright posture,

predetermined with variable expression based on the TWIN STUDIES

theory of multifactorial inheritance.

POPULATION DIFFERENCES Identical twins are derived from a single fertilized egg,
and so are genetically identical. Any differences
Most interesting genetic difference suggested by the between them must, therefore, be due to the
epidemiological data concerns the relatively high environment. Nonidentical twins are just like any

Genetics in Orthodontics 309

brothers and sisters, but happen to be born at the same twins are identical in genetic makeup and sex.
time. Dizygotic twins (Fig. 27.2) have a different genetic
composition, and half the pairs are different sexed.
Monozygotic (identical/MZ) twins (Fig. 27.1)
originate from one fertilized egg that divides later on, Monozygotic twins are seen with a frequency of
whereas dizygotic (nonidentical/DZ) twins originate 3.5 to 4 per thousand maternities in all races, at all
from two separately fertilized eggs. Monozygotic maternal ages, and for all parties. The frequency of

Patient 1

Pateint 2

Fig. 27.1 : Monozygotic twins

Textbook of Orthodontics

Fig. 27.2: Dizygotic twins

Genetics in Orthodontics

DZ twins varies from 3.5 to 18 per thousand and Figs 27.3Aand S: Characteristicshape of the lowerlip
increases with maternal age and parity. DZ twins also ina fatherand daughter
show large racial variations. The inheritance of DZ
twinning is confined to be female line, an increased Developmental abnormalities of cleft Iip and / or
twinning rate being found among the relatives of the palate could result from:
mothers and not of the fathers of twins. • Functional abnormalities, because of the lack of

Early twins studies and intra-familial comparison attachment of the muscles of the lip and the nares
indicated that genetic factors would have a more onto the septum and"the anterior nasal spine.
important influence than non-genetic ones for occlusal • Malformed growth of the facial buds.
traits. This led orthodontists to the idea that only genes Results from MZ and DZ twin studies has revealed
would cause malocclusion. This conclusion, however, that:
was premature and the matter seemed much more • The structure of the individual bones seems to be
complex as our knowledge on the subject has under the influence of rather rigid hereditary forces
increased. but that the greatest variation in the craniofacial
complex in each group was found in the spatial
Twin studies have revealed that: arrangement of the bony elements rather than
• Genetic variation has a major effect on arch width within those elements. This supports the notion
that the cranial base and mandible have areas or
and length. zones that may permit spatial adjustment during
• A genetic contribution to arch shape (the maxillary growth and development responding to functional
demands.
being greater than the mandibular). • Knowledge of the inheritance of functional compo-
• Identical twins were not occlusally identical. nents and their heritability is as yet not clear.
• Highest heritability coefficient for the proportion
CONCLUSION
facial height to facial depth and for the proportion
maxillary to mandibular sella-apical base. Our knowledge of the inheritance of oral and facial
• Greater genetic basis for tooth size and shape. structures has grown over the years. Yet, there is scope
• Crown dimensions were largely under genetic for further research and longitudinal studies of families
control. (family pedigree studies) as well as random samples
• A wider range of genetic factors were found to of total populations are necessary to understand the
influence the mandibular teeth as compared to genetic contribution of variations in occlusion. The task
maxillary teeth. has been made more difficult because of inbreeding
and outbreeding, leading to a lack of availability of
FUNCTIONAL COMPONENTS OF THE FACE pure genetic pools.

Tongue movements, mouth opening and closing are It is important to understand that since the
the first muscle activities in the facial region, starting expression of heredity is partially dependent on the
around the ninth week after conception. Between the environment, hence it may be possible to influence the
tenth and fourteenth week, the trigeminal nerve development of hereditary characteristics by changing
innervated zones start reacting to stimulus. Hwnan the environment of a person or in future, by modifying
fetuses swallow from about the twelfth week in utero. the genetic coding in individual chromosomes by
genetic engineering.
In very early development, predominantly here-
ditary factors arc active. It is therefore believed that
the genetic information for facial growth is primarily
situated in the neuromuscular systems and soft tissues.
Genes are important in determining shape and surface
of muscles and other soft tissues, especially the lip
shape (Figs 27.3A and B). This indirectly influences
the hard tissue growth.

312 Textbook of Orthodontics

FURTHER READING 8. Missey PA. The heritability of malocdusion. 1. Genetics,
principles and terminology, Br J Orthod 1999;26:103.
1. Harris EFl ]ohnson MG. Heritability of craniometric and
occlusal variables: a longitudinal sib analysis, Am] Orthod 9. Missey PA. The heritability of rnalocclusion. 2. The
Dentofac Orthop 1991;99:258-68.
influence of genetics in malocclusion, Br J Orthod
2. Harris EF, Smith RJ. A study of occlusion and arch widths 1999;26:195.
in families, Am J Orthod 1980;78:155-63.
10. PeckS, Peck L, KatajaM. Mandibular lateral incisor-canine
3. Harris]E, Kowalski C], Watnkk SS. Genetic factors ill the
shape of the craniofacial complex, Angle Orthod transposition, concomitant dental anomalies, and genetic
1973;43:107. control, angle Orthod 1998;68(5):455-66.
11. PeckS, Peck L,Kataja M. Mandibular lateraLincisor-eanine
4. Harris]E, Kowalski CJ. AIi in the family: use of familial transposition, concomitant dental anomalies, and genetic
control, angle Orthud 1998;68(5):455-66.
information in orthodontic diagnosis, case assessment,
12. Thesleff 1. The genetic basis of normal and abnormal
and treatment planning, Am J Orthod 1976;69:493. craniofacial development, Acta Odontol Scand
5. Hartsfield JK j-. Everett ET, Ai-Qawasmi RA. Genetic 1998;56:321.

factors in external apical root resorption and orthodontic 13. Vanco C, Kasai K, Sergi R, etal. Genetic and envirorunental
treatment. Crit Rev Oral Bioi Med 2004;15(2):115-22. influences on facia] profile, Aust Dent J 1995;40:104.
6. Lauweryns 1, CareIs C, Vlietinck R. The use of twins in
Dentofacial genetic research, Am J Orthod Dentofac 14. Wolff G, Wienker TF, Sander H. On the genetics of
Orthop 1993;103:33-38.
7. Litton SF, Ackerrnan LV, Isaacson RJ, Shapiro B. A genetic mandibular prognathism: analysis of large European
study of Class ill malocclusion, Am J Orthod 1970;58:556- noble families, J Med Genet1993;30:112-6.
77.

Cosmetic Contouring
in Orthodontics

Gurkeerat Singh

• Introduction
• Procedure
• Uses and advantages

INTRODUCTION with finely ground diamond burs. The considerations
which should be kept in mind before undertaking
Orthodontic therapy is still considered to be exclu- cosmetic contouring (Table 28.1) are mainly with the
sively an esthetic proced ure. The alignment and shape amount of enamel required to be removed. The
of the anterior teeth play a major role in defining the amount of tooth reduction involved is generally
beauty of a smile. As a student of orthodontics, you minimal and hence no anesthesia is required. It is
will be expected to treat cases which will involve a generally a onetime procedure and once treatment is
muitidisciplinary approach towards treatment. It is complete, no replacemen ts or touch-ups are necessary.
sometimes preferred to recontour a tooth rather than The cost and time involved are minimal. Extensive
do cosmetic restorations with their inherent chances contouring can cause exposure of the dentine, discolo-
of fracture. The decision for such treatment should be ration, susceptibility to future decay and sensitivity.
made before starting active treatment.
Table 28.1: Considerationtso be keptinmindbefore
Cosmetic contouring has been used for esthetic undertakingcosmeticcontouring
purpose for a long time. It is the ideal treatment for
small fractures and chips. When performed success- 1. Thethicknessof enamel
fully, it is generally the most preferred therapy because 2. Shapeand locationof thepulp canals
no anesthesia is required, it is relatively inexpensive, 3. Thelengthof the tooth
and takes less time than most other procedures. 4. Thelengthand positionof the adjacenttccth

PROCEDURE Contouring when combined with orthodontics can
help overcome certain disadvantages inherent in the
The procedure involves the use of fine diamond burs technique. Contouring will cause a chipped tooth to
to provide the desired contour to the incisal edges of appear shorter than its adjacent teeth unless ortho-
the teeth. This may involve the use of long tapered dontics is used to increase its clinical crown length.
burs or the doughnut bur, depending upon the This can be easily achieved by the orthodontist; by
requirement. Finishing is done with the smoother (less altering the height of the bracket during placement.
abrasive) finishing burs and the final polishing using The bracket on the tooth to be elongated is placed more
a pumice paste and rubber cups. gingival to the brackets on adjacent teeth. Thereby
once the teeth are aligned this particular tooth appears
USES AND ADVANTAGES elongated but following cosmetic contouring the
alignment is restored (Figs 28.1 to 28.3).
Cosmetic contouring is a simple, painless procedure
performed by reducing some of the tooth structure

314 Textbook of Orthodontics

Fig. 28.1A: Shape and length of the incisors before Fig. 28.18: More esthetically contoured teeth
incisal contouring at the end of orthodontic treatment seen after incisal contouring

Fig. 28.2A: Pre-treatment photographs showing a chip on the Fig. 28.28: The bracket on the right central incisor is placed
mesio-incisal angle of the right central incisor. Mamolons are 0.5 mm gingival to the contra-lateral bracket. It appears
also very prominent in this case elongated as compared to the left central incisor

Fig. 28.2C: The post-treatment view after cosmetic
contouring and completion of the orthodontic therapy

Cosmetic contouring can also be done to achieve a of active orthodontic treatment using the cosmetic
more esthetic appearance even after the completion contouring technique (Fig. 28.4).
of orthodontic treatment. Female teeth appear more
rounded as compared to male teeth. A more rounded Cosmetic contouring is just another esthetic
contour can be imparted to teeth following completion procedure which should be kept in mind at the
conceptual stage of orthodontic treatment planning.

Cosmetic Contouring in Orthodontics

Fig. 28.3A: The post-treatment view after cosmetic Fig. 28.4A: Intraoral view before undertaking cosmetic
contouring and completion of the orthodontic therapy contouring, the teeth appear spatulate. The patient was
recommended a combination of periodontal surgery to decrease
the length of her crowns; and cosmetic contouring to change
the shape of her teeth. The patient refused periodontal surgery,
as it would involve injections and surgery per Se

Fig. 28.38: The post-treatment view after cosmetic Fig. 28.48: Intraoral photograph after cosmetic contouring a
contouring and completion of the orthodontic therapy more rounded or feminine appearance

Fig. 28.3C: The post-treatment view after cosmetic Since the procedure is relatively simple and decreases
contouring and completion of the orthodontic therapy the chances of repeated touch-ups, its advantages over
cosmetic restorations (Table 28.2) should be weighed
before imparting treatment.

Table 28.2: Advantages of cosmetic contouring over
cosmetic restorations

1. It is a one time procedure which does not
require repeated and time consuming touch-ups

2. Time required is minimal
3. Less expensive
4. No chances of discolorations or fracture

FURTHER READING

1. Goldstcin Ronald E. Cosmetic Contouring: Tdeal for Minor
Damage; Change Your Smile. 3rd Edition; Quintessence
Publication Company !ne 1996;91-92.

Detrimental Effects of
Orthodontics Treatment

Gurkeerat Singh

• Introduction
• Tissue damage during treatment
• Increased predisposition to dental disease and dysfunction

INTRODUCTION TISSUE DAMAGE DURING TREATMENT

Orthodontic treatment has its shortcomings. These TRAUMATIC ULCERATIONS
perceived shortcomings are not restricted to a lack of
ability to treat certain malocclusions but to the possi- Pain associated with traumatic ulcerations (Fig. 29.1)
bility of actual tissue damage during the actual course or abrasions are the most common complaints
of treatment, an increased susceptibility to dental reported following the placement of fixed appliances.
disease and dysfunction following completion of A study conducted by us found the incidence to be as
treatment, and partial or complete failure to accom- high as 56 percent Over all; with females complaining
plish the goals of treatment. The detrimental effects more as compared to males. The patients treated with
of orthodontic treatment cannot be segregated from the Begg appliance had more problems, mainly
the shortcomings in the implementation of the because of the sharp ends of the lock-pins used.
treatment per se. Only part of the treatment is in the
hands of the clinician. From the perspective of an ideal Such problems can be relieved by adjusting the
treatment plan the patient's cooperation (Table 29.1) appliance, using good quality lock pins/brackets or
is paramount for achieving ideal result. using relief silicone (Fig. 29.2), or relief wax (Fig. 29.3).
The relief silicon is preferred over relief wax as it does
Table 29.1: Patient's cooperation not melt or freeze or dry out with change in storing
lor an ideal treatment temperature.

During orthodontic treatment the patient is supposed to Fig. 29.1: Traumaticulcerassociated with
fixed orthodonticappliance
Maintain proper oral hygiene

Not damage or break parts 01 the appliance,this will
involve abstaining from certain hard and sticky
foodstuffslike, chocolates,toffees,ete.

Wear the advised elastics/headgears and retainers for
the required duration

Report for appointments regularly

Meet his/her financial obligations towards the
treatment

Detrimental Effects of Orthodontics Treatment

Fig. 29.3: Reliefwax

PERIODONTAL DISEASE Fig. 29.5:A floridresponseto fixedorthodonticappliance
necessitated premature removal for periodontal reasons
A generalized, mild to moderate gingivitis occurs
within 6 weeks of placement of fixed orthodontic Maintenance of poor oral hygiene while wearing
appliances (Fig. 29.4).This may persist until the appli- removable orthodontic appliances can lead to an
ance is removed and may exacerbate during treatment inflammation of the gums (Fig. 29.6A) especially of
depending upon the patient's compliance with oral the palatal tissues. Elastometrics worn along with fixed
hygiene procedures. orthodontic appliances have a tendency to accumulate
food debris (Fig. 29.6B). Candidial infections in the
At times the hyper-plastic response can be florid
and might necessitate the removal of the fixed appli-
ance prematurely (Fig. 29.5) and/or intervention by a
periodontist to maintain acceptable levels of oral
hygiene.

318 Textbook of Orthodontics

Fig. 29.6A: Calculas deposits and over-all poor oral hygiene Fig. 29.7: Candidial infectionin the palate along with
removable appliance therapy
maintenance associated with removable appliance wear

Fig. 29.8: Loss of attachment followingfixed orthodontic
appliance therapy

Characteristics lesions (Fig. 29.9B) can be seen
around brackets following debonding. Food tends
Flg.29.6B: Elastometricchains can cause plague accumulation accumulate around brackets, especially gingivally,

palatal region may rarely be seen along the palatal
folds (Fig. 29.7).

Poor oral hygiene may lead to a generalized loss
of alveolar bone height. This can be expected more
adjacent to the extraction sites. Loss of attachment (Fig.
29.8) can be 0.5-1.5 mm in 5-10 percent of the patients
treated. It is pertinent to note that loss of attachment
is more for teeth that have been excessively tipped.

CARIES Fig. 29.9A: Hypocalcificationand an increased

The incidence of caries increases during orthodontic predisposition to caries seen following orthodontic treatment
treatment. This is especially true if the patient does
not follow proper oral hygiene procedures and / or
the bands are loose (Fig. 29.9A).

Detrimental Effects of Orthodontics Treatment 319

Fig. 29.9B: Characteristichypo-calcification Fig. 29.10: Extremebone loss and mobilityfollowing
lesions gingivalto bracket
excessive use of force and tipping

causing hypo-calcification of enamel. These can be
entirely prevented by maintaining a proper oral
hygiene regime and the regular use of fluoride mouth
washes.

Susceptibility to proximal caries also increases if
proximal stripping is undertaken. The use of course
diamond burs and a lack of finishing procedures
increases the risk.

ROOT RESORPTION Fig. 29.11: Excessive root resorption
following orthodontic treatment
Root resorption is a frequent occurrence during ortho- indicated by the bluntingof the root
dontic procedures. It is usually small in amount,
irreversible and difficult to predict. apices, in teeth with a previous history
of trauma
It has been often associated with the excessive use
of force, or tipping (Fig. 29.10) or when the roots are Pulpal damage has also been reported with the use
moved beyond the cancellous bone, closer to the of removable appliances where a labial bow may be
cortical bone (as during anchorage preparation in the excessively activated to produce tooth movement.
edge-wise technique). The amount of root resorption
is considerably more for teeth that have undergone
root canal treatment, are non-vital or have been
subjected to previous trauma (Fig. 29.11).

PULPAL DAMAGE INCREASED PREDISPOSITION TO DENTAL
DISEASE AND DYSFUNCTION
The minor circulatory changes accompanying
orthodontic tooth movement generally have no PERIODONTAL DISEASE
adverse pulpal effects. If excessive forces are applied,
due to the overzealous wearing of elastics by the If appropriate oral hygiene is maintained and ideal
patient or in-expert handling of the orthodontic appli- finish is achieved there is no increase in the predis-
ance, pain may ensue, which may occasionally result position to periodontal disease following orthodontic
in irreversible pulpal damage and pulpal death. treatment.

320 Textbook of Orthodontics

However, if proper ora I hygiene has not been treatment is done using a removable appliance (Fig.
maintained during treatment or if ideal results have 29.13).
not been achieved following orthodontic treatment
then the risk of periodontal disease is considerably MANDIBULAR DYSFUNCTION
increased.
Orthodontic therapy has often been blamed for
This is especially true if extraction spaces open up. causing mandibular dysfunction, but no statistical
The gap created causes frequent food lodgment and correlation has been found between fixed orthodontic
pocket formation (Fig. 29.12). If an excessive overbite treatment and mandibular dysfunction. It is important
is created, it might lead to a traumatic overbite and to note that with advancing age the adaptability of
periodontal breakdown is the maxillary and mandi- the temporomandibular joint (TMJ) decreases. Special
bular incisor region. This is more frequently seen when care should to exercised, when treating adult patients.

Fig. 29.12: Food lodgement and pocket formation Fig. 29.13: Unresolved deep bite and resultant trauma
mesial to maxillary first molars in a second pre- from occlusion in a case treated with removable
molar extraction case orthodontic appliance

Fig. 29.14: Partial treatment failure; extraction spaces have opened up partially, right molars
are in end-on relationship, the midlines are not coinciding and the over-bite is increased

Detrimental Effects of Orthodontics Treatment 321

Fig. 29.15: Total treatment failure; extraction spaces have reopened in all the four quadrants, anteriors are
crowded and the deep bite persists. The photographs give an appearance of pre-treatment records!

Do not forget to examine and monitor their TMJ before, allergy associated with a transpalatal arch appliance, J
during and after treatment.
Orthofacial Orthop 2002;6:501-9.
FAILED TREATMENT 6. DcShields RW. A study of root resorption in treated Class

Treatment failure, partial (Fig. 29.14) or total (Fig. IT, Division 1 malocclusion. Angle Orthod 1969;39:231-45.
29.15) is perhaps the greatest risk. Whatever the 7. Geiger AM. Mucogingival problems and the movement
reasons (Table 29.2) for treatment failure this should
only stimulate further research and help provide more of mandibular incisors. A clinical review. Am J Orthod
stringent quality orthodontic treatment.
1980;78:511-27.
Table 29.2: Reasons for treatment failure 8. Grieg A. Contact dermatitis and cervical headgear, Br Dent

• Underestimation of skeletal discrepancy I 1983;1:12-14.
• Misjudgement of space requirements 9. Grieg DGM. Contact derma ti tis; Reaction to a meta Ibuckle
• Misjudgement of anchorage requirements
• incorrect choice of appliance on a cervicai head gear, Br Dent I 1983;155:61-62.
• Faulty technique 10. Hall AM. Upper incisor root resorption during stage IT of
e Poor patient compliance
the Begg technique: Two case reports, Br J Orthod
FURTHER READING
1978;S:47-50.
1. Booth-Mason D, Bimie D. Penetrating eye injury from 11. Kameda A. A case with crestal bone loss caused by
headgear, Eur I Orthod 1988;10:111-4.
orthodontic procedures, J lap Orthod Sac 1973;32:334-5.
2. Barber AF, Sims MR. Rapid maxillary expansion and
external root resorption in man: A scanning electron 12. Kerosuo H, Kullaa A , Kerusuo E, Kanerva L, Hensten

microscope study. Am IOrthod 1981;79:630-52. PA. Nickel allergy in adolescents in relation to orthodontic

3. Bishara SE. Oral Lesions caused by an orthodontic treatment and piercing of ears, Am J Orthod Dentofacial

retainer: A case report. Am J Orthod Dentofacial Orthop Orthop 1996;109:148-54.
13. L' Abee EM, Sanderink GCH. Apical root resorption
1995;108:115-7.
4. B1aschko A. Nickel eczema, Br I Dermat 1953;65:84-85. during Begg treatment, Am IOrthod, 1985;19:60-61.
5. Count A, Millar MA, Khakharia ML, Strang S. Nickel 14. Mirabella AD, Artun J. Risk factors for apical root

resorption of maxillary anterior teeth in adult orthodontic
patients, Am I Orthod Dentofacial Orthop 1995;108:48-

55.
15. Zachrisson BU, Alnaes L. Periodontal condition in

orthodontically treated and untreated individuals. T.Loss

of attachment, gingivai pocket depth and clinical crown
height. Angle Orthod 1973;43:402-11.
16. Zachrisson BU. Gingival condition associated with
orthodontic treatment. IT. Histological findings. Angle
Orthod 1972;41:352-7.

Seeti n Four

~~'""-"""'~~'~

MATERIALS

30. Material Used in Orthodontics-Introduction and
Archwire Materials

31. Bracket Material and Auxiliary Force Delivery Systems
32. Impression Materials
33. Luting Materials
34. Adhesion Promoters and Bonding Materials
35. Orthodontic Instruments
36. Sterilization in Orthodontics

Material Used in
Orthodontics-I ntroduction

and Archwire Materials

Gurkeerat Singh

• Introduction • Archwirematerials
• Classificationof orthodonticappliance • Classificationof archwire materials

materials

INTRODUCTION orthodontics. These materials will overlap and each
should be studied based upon its application in the
The rapid advancement seen in the field of field of orthodontics. Certain topics, for example the
orthodontics has been primarily due to the improve- impression material, have been covered in less detail.
ment in the field of material sciences. The better Only alginates are covered, as this is the most
understanding of biologic problems and advance- frequently used impression material in orthodontics.
ments in orthodontic materials has lead to improved It is recommended that the students refer relevant
appliance designs and treatment strategies. books on the topic for further clarification.

This chapter will aim to cover in brief, the materials ARCHWIRE MATERIALS
used commonly in the day to day practice of
orthodontics. The aim is to provide the students an Archwires are the base wires, which are engaged in
understanding of the latest means and ways in which brackets of the various appliance systems. These are
orthodontic treatment is done. The profession still does used to provide a proper arch form and / or provide
not have specifications for orthodontic materials and a stable base to which the auxiliaries can be attached
the classification provided is only to categorize these to generate the tooth moving forces.
materials and to make their study easy.
Characteristics of orthodontic wires, which are
CLASSIFICATION OF ORTHODONTIC considered desirable for optimal performance during
APPLIANCE MATERIALS treatment include;
1. Large springback
1. Archwire materials 2. Low stiffness
2. Bracket and attachment materials 3. High formability
3. Auxiliary force delivery systems 4. High stored energy
4. Impression materials 5. Low surface friction
5. Luting materials 6. Biocompatibility and environmental stability
6. Sealants and Adhesion promoters 7. Capability to be welded or soldered to auxiliaries
7. Etching/conditioning and crystal growth systems
8. Bonding materials and attachments.
These characteristics also change according to the
The categories defined are broadly based on the stage of treatment and the purpose for which the arch
use of the particular material in the field of wire is being used.

326 Textbook of Orthodontics

SPRING BACK FRICTION

Springback is also referred to as maximum elastic The preferred wire material for moving teeth relative
deflection or working range. Springback is related to to the wire should produce the least amount of friction
the ratio of yield strength (YS)to the modulus of elasti- at the bracket/wire interface. Excessive friction can
city (E) of the material (YS/E) (Fig. 30.1). result in loss of anchorage or binding accompanied
by little or no tooth movement.
Higher springback values provide the ability to
apply large activations with a resultant increase in BIOCOMPATIBILlTY AND
working time of the appliance; thus, decreasing the ENVIRONMENTAL STABILITY
number of archwire changes. It is also a measure of
how far a wire can be deflected without causing Biocompatibility includes resistance to corrosion and
permanent deformation. tissue tolerance to elements of the wire. Environmental
stability ensures the maintenance of desirable
STIFFNESS OR LOAD DEFLECTION RATE properties of the wire for an extended period of time
after manufacture. These are essential to ensure the
This is the force magnitude delivered by an appliance predictable behavior of the wire when in use.
and is proportional to the modulus of elasticity (E).
CAPABILITY TO BE WELDED OR SOLDERED
Low stiffness leads to an ability to apply lower TO AUXILIARIES AND ATTACHMENTS
forces, a more constant force to be delivered over time
and greater ease and accuracy in applying a given This increases the utility of the wire since more auxili-
force. aries can be fixed onto it.

FORMABILlTY

High formability provides the ability to bend a wire CLASSIFICATION OF ARCHWIRE MATERIALS
into desired configurations such as loops, coils .etc.
without fracturing the wire. 1. Classification of arch wire materials based on
material constituent
MODULUS OF RESILIENCE Ms a. Gold
b. Stainless steel
This property signifies the energy storing capacity of c. Chrome-cobalt
the wire. It is represented by the area under the line d. Nickel-titanium
describing elastic deformation of the wire (Fig. 30.2).

Yield strength
Proportional limit

Stiffness a W
Springiness Cl 1/E

Fig. 30.1: Stress and strain curve for an orthodontic wire Formability---+-

Strain

Fig. 30.2: Resilience and formability are defined as an area
under the stress-strain curve and a distance along the X-axis
respectively

Material Used in Orthodontics-lntroduction and Archwire Materials 327

• Martensitic, and austenitic Platinum-5-1O%
• Superelastic, and thermodynamic/ tempe- Nickel-1-2 %
Zinc-traces
rature transforming
e. Beta titanium Addition of copper permitted age hardening. Silver
f. Alpha titanium was mainly added to counter the color of copper.
g. Titanium niobium alloy Palladium and platinum increased the melting
h. Multi-stranded arch wires temperature. Nickel increased the strength and tarnish
I. Composite/coated wires resistance of the alloy. Zinc provided the antioxidant
j. Optiflex archwires properties to the alloy.
2. Classification of archwires according to cross-
section: Advantageous properties
a. Round 1. Extremely formable
b. Square 2. Strength can be increased by heat treatment as well
c. Rectangular
d. Miscellaneous as cold working
3. Classification of archwires based on the diameter 3. Low modulus of elasticity
of the arch wire 4. Good environmental stability
a. Round 5. Good joinability
6. Excellent biocompatibility.
• O.OS"
• 0.10" Disadvantageous properties
• 0.12" 1. Low yield strength
• 0.14" etc. 2. Low springback
b. Square 3. High cost.
• 0.16" x 0.16"
• 0.17" x 0.17" etc. STAINLESS STEEL
c. Rectangular
• 0.17" x 0.25" Introduced in 1929by Wilkinson. Ever since this mate-
• 0.17" x 0.2S" etc. rial was introduced to orthodontics, it has formed the
4. Classification of archwires according to the basis of most orthodontic wires. lts stiffness and
microstructural arrangement resiliency were of great importance. Stainless steel was
a. Simple cubic derived by the addition of chromium to iron. Mainly
b. Face centered cubic the austenitic form is made use of in orthodontics.
c. Body centered cubic.
Both, round (Fig. 30.3A) and rectangular (Fig.
GOLD 30.3B) wires are made from stainless steel. Their use
is dependent on the technique practiced, the stage of
Gold alloys were used prior to the 1930s. They were treatment and the stiffness required (the purpose for
inert, biocompatible and environmentally stable. The which it is being used- retraction/ aligning/ finishing
other materials available were unable to tolerate the etc.).
extracting oral conditions.
Composition
According to American Dental Association classifi- Iron-71 %
cation gold alloys are of two types: Chromium-1S%
a. Type I-increased gold content Nickel-DS%
b. Type ll-relatively lesser content of gold Carbon less than-D.2%

Composition Advantageous properties
Gold-15-65% 1. High stiffness
Copper-11-1S% 2. High yield strength- 1400 MPa approx.
Silver-10- 25% 3. High resilience
Palladium-5-1O%

328 Textbook of Orthodontics

Disadvantageous properties
1. Soldering is demanding
2. Lower springback than Nickel-titanium alloys.
3. High modulus of elasticity.
4. More frequent activations are required to maintain

the same force levels.
5. Heating to temperatures of 400-900 degrees causes

the release of nickel and chromium, thereby decrea-
sing the corrosion resistance of the alloy.

o Australian Stainless Steel Wires

Fig. 30.3A: Round stainless steel wire Dr PR Begg in collaboration with Mr AJ WiJcock, an
Australian metallurgist developed a more tensile wire
Fig. 30.38: Rectangular stainless steel wire material which was thin enough to distribute optimal
4. Good formability tooth moving forces for long periods, over long
5. Good environmental stability distances with minirnalloss in the intensity of force.
6. Good joinability The diameter of these wires has been decreasing with
7. Adequate springback the changing concepts of lower force levels being used
8. Biocompatible in orthodontics.
9. Corrosion resistant, except at weld sites
10. Economical. They are of the following types:
1. Regular (Fig. 3o.4A)
2. Regular plus (Fig. 30.4B)
3. Special (Fig. 3o.4C)
4. Special plus (Fig. 30.4D)
5. Special plus pulse straightened (Fig. 30.4E)
6. Premium (Fig. 30.4F)
7. Premium Plus (Fig. 30.4G)
8. Premium plus pulse straightened (Fig. 3o.H)
9. Supreme (Fig. 30.41)
10. Supreme pulse straightened (Fig. 3o.4J)
These wires are available as spools as well as in
straight lengths.
The manufacture of these wires involves two
processes, the spinner straightening, for regular to
extra special wires. The pulse straightening process is
used for the newer premium and supreme wires.
Spinner straightening involves the pulling of the wire
in its cold drawn condition through rotating bronze
rollers which torsionally twist the wire into a straight
condition. The wire so formed has certain amount of
resultant deformation, a decrease in yield stress values
and it becomes strain softened.
In pulse straightening, the wire is pulsed in a
special machine, permitting high tensile wires to be
stra ightened and smaller diameter wires can be
manufactured. This wire has a smoother finish and a
higher tensile strength. These wires show a signifi-
cantly higher working range and good recovery
patterns.

Material Used in Orthodontics-lntroduction and Archwire Materials 329

A3W 232400 AJW 232410

REGULAR REGULAR .PLUS
.018" .018"

Stainless Steel Stainle •• Steel
Heat Treated Arch Wire Heat Treated Arch Wire

25ft Coil 25ft Coil
REF: I002.RIT C0615 REF: 803.RIK C0617

A.J. WILCOCK PTY. LTD. A.J. WILCOCK PTY. LTD.
45 Yea Road 45V.a Roed

Whittlesea 3757 Australia Whlttleeel 3757 Auetrllla
03 9716-2126 03

Fig. 30.4A: Regular AJ Wilcock wire packing Fig. 30.4B: Regular Plus AJ Wilcock wire packing

AJW 231320 AJW 231330

SPECIAL SPECI.ALPLUS
.016" .016"

Stainless Steel Stalnles. Steel
Heat Treated Arch Wire Heat Trel!!~ Arch Wire

25ft Coli 25ft Coli
REF: 804.RCI C0719
REF: 306.ROA C0940
A.J. WILCOCK PTY. LTD.
45 Yea Road A.J. WILCOCK PTY. LTD.
46 Yea Roed
Whlttlesea 3757 Australia
Whlttlesea 3757 Australia
Fig. 30.4C: Special AJ Wilcock wire packing 03 9716-2125

Fig. 30.40: Special Plus AJ Wilcock wire packing

330 Textbook of Orthodontics

Fig. 30.4E: Special plus pulse straightened AJ Wilcock wire AJW 231340
packing
PREMIUM
.016·~

Stainless Steel
Heat Treated Arch VIIIre

25ft Coil
REF: 10S.ROO 80614

A.J. WlLCOCl( PTY. LTD•

••• Yea·Road
WlIttI_ 3757Australia

Fig. 30.4F: Premium AJ Wilcock wire packing

AJW 231350 Fig. 30.4H: Premium plus pulse straightened
AJ Wilcock wire packing
PREMIUM PLUS
.016"

Stainless Steel
Heat Treated Arch Wire

25ft Coli
REF: 805. RKK 80980

A.J. WILCOCK PTY. LTD.

45 Yea Road
Whlttle"a 3757 Australia

03 9718·2128

Fig. 30.4G: Premium plus AJ Wilcock wire packing

Material Used in Orthodontics-Introduction and Archwire Materials 331

AJW 228-060

SUPREME Fig. 30.4J: Supreme pulse straightened AJ Wilcock wire
.010" packing

Stainless Steel
Heat Treated Arch Wire

25ft Coil

REF: 904.TAO C0669

A.J. WILCOCK PTY. LTD.
45 Yea Road

Vllhittlesea 3757 Australia
03 9716-2126

See reverse for bending Instructions.

Fig. 30.41: Supreme AJ Wilcock wire packing

CHROME-COBALT

Also known as Elgiloy.
These wires have properties similar to those of
stainless steel but can be supplied in the softer and
more formable state and then could be hardened by
heat treatment. This process increases the strength of
the wire significantly.

Composition Fig. 30.5: Blue Elgiloy (preformed) archwire packing
Coba It--40%
• Green-semi-resilient
Chromium-20% • Red-resilient
Nickel-15%
Iron-15.4% The wires made from this alloy are generally
Molybdenum--D7% supplied in the ductile form, allowing them to be easily
Manganese--D2% deformed and shaped into appliances. These are then
Beryllium--D.4% heat treated to increase their strength. The standard
Others--D.05% heat treatment involves heating to 483 degrees

This alloy is manufactured in four tempers,
depending on the amounts of cold work:
• Blue-soft and easy to bend (Fig. 30.5)
• Yellow-ductile

332 Textbook of Orthodontics

centigrade for 7 to 12 minutes. Low temperature heat omposition
treatment causes a phase change and stress relief. Nickel-54-55%
Heating to 1100-1200 degrees centigrade and Titanium-43-44%
quenching can soften the wire. Cobalt-1.6-3%

Advantageous properties Thermal nitinol (Fig. 30.7) shows shape memory
1. Excellent tarnish and corrosion resistance. in the martensitic phase. These archwires are formed
2. Greater resistance to fatigue than stainless steel. to the desired shape in the martensite form and they
3. Greater resistance to distortion. go through the transition temperature range (TIR) to
4. Good formability. the austenite grain structure (Fig. 30.8).In the austenite
5. Functionally remains active for longer duration if grain structure it is deformed to confirm to the irregu-
larities in the arch form; taking the wire through TIR
used as a resilient spring again will result in its original shape in the marten-
sitic form. A number of variations of the Ni-Ti alloy
Disadvantageous properties have been developed in dentistry. Compositional
1. Has to be heat treated. variations lead to changes in the martensitic and
2. Soldering is demanding. A low fusing solder has austenitic start and finish temperatures and mecha-
nical properties. The wires with austenitic finish
to be used. These wires should be soldered with a temperatures less than 37 degree centigrade exhibit
silver solder in the presence of a fluoride flux or superelasticity.
can be joined by spot welding.
3. The modulus of elasticity is high causing higher Elastic Ni-Ti Alloy
forces to be delivered for similar activations as
stainless steel wires. Elastic Ni-Ti alloy is used in the martensitic phase. Tt
maintains its high elasticity and flexibility. This wire
NICKEL-TITANIUM also exhibits the desirable property of lighter
continuous forces on deformation.
Composition
Nickel-55% Advantageous properties
Titanium-45% 1. High spring back
2. High stored energy
This alloy was developed in 1971, and marketed as 3. High elasticity.
'Nitinol'. The name nitinol is an acronym derived from
the elements which comprises the alloy (Nickel, ti- Disadvantageous properties
titanium, nol-naval ordinance laboratory). It had 1. High friction as compared to stainless steel.
exceIJent springback properties (Fig. 30.6). 2. Low stiffness cannot be used at the completion

Modifications to the initial composition provided stages of orthodontic treatment.
alloys, which had shape memory, elasticity and 3. Fractures easily if bent over a sharp edge.
flexibility. Newer alloys are even thermal activated, 4. Very limited bending is possible.
i.e. exert tooth moving forces only after reaching a 5. Cannot be welded or soldered.
certain temperature. This was achieved with the 6. Expensive as compared to stainless steel wires.
addition of smaIJ amounts of copper.
Copper Ni-Ti Alloys
Nitinol is basically is of two types:
1. Thermal nitinol, and This alloy was developed by Or Rohit Sachdeva and
2. Elastic nitinol Miyasaki in 1994.

Thermal Ni-Ti Alloy Composition
Titanium--42.99%
Initially, composed of equal parts of nickel and Nickel-49.87%
titanium. Chrornium-D.50%
Copper-5.64%

Material Used in Orthodontics-lntroduction and Archwire Materials 333

Size; Niti .016- Upper
Form: Tl'UefCm1

Qty: 10 Pes
lot: #586

BIIII~,IJmll.

(a) (b)
Fig. 30.6: Various form of NiTialloy wire available commercially(a) preformed round (b) preformed rectangular, or (c) spools

Fig. 30.7: Heat activated Ni-Tiwire. Note the high flexibilityof the wire

'0 B E The addition of copper decreases the difference
C between loading and unloading forces ca using
~ Ba F delivery of more constant forces for small activations.
~ Or in other words, unloading forces more closely
U5 of approximate loading forces. The addition of copper
also increases surface smoothness making the surface
Strain roughness similar to untreated TMA wires. Copper
content also plays an important role in controlling the
Fig. 30.8: A stress-strain curve illustratingsuperelasticity due transformation temperature of the alloy.

the stress-induced transformation from the austenitic to the The stress induced martensite is responsible for the
martensitic phase. Point F indicates the maximum stress on superelastic characteristic of Ni- Ti alloys. However,
which the stress-induced martensitic structure on unloading can martensite transformation is also temperature
exist, and at that point the reverse transformation to austenite dependent. The stability of the martensite and/or
austenite phase at a given temperature is based upon
begins the transformation temperature of the alloy. The most
important marker is the materials Austenitic finish (Af)

temperature. To exploit superelasticity to its fullest

334 Textbook of Orthodontics

potential, the working temperature of the orthodontic
appliance should be greater than the Af temperature.

Four types of copper Ni- Ti alloys were developed:

Type I 1i~1IIi1;liil.ll!Size: CNA .016- x .022- LOW'er
- At 15°C
- not used clinically f-~\\FOO11: Truefcnn
- exerts very high forces. 'c:11Qly· 10 Pes

Type 11 01
- At 27°C
CIf.A.CZZL

- normally used in patients with average pain Size: CNA .016- Upper
tolerance Form: Truefoon
10 Pes
- periodontium should be healthy Qly: #465
- constant force is generated. Lot
Type III
- At 35°C 1111111111111111
- Used in patients with a low threshold c:llA161"
- Normal to slightly compromised periodontium
- Used only where low forces are desired.

Type IV
- At 40°C
- Used in patients with low pain threshold
- Where tooth movement is to be slow
- Intermittent forces are generated
- Used as an initial aligning archwire.

Advantages of copper Ni- Ti alloys Fig. 30.9: CNA arch wires
1. More resistant to permanent deformation
2. Better springback as compared to other Ni- Ti alloys
3. More constant forces are exerted over small

activations.

BETA TITANIUM OR TMA WIRE OR the surface treatment of these wires decreases the
CNA WIRE (FIG. 30.9) frictional forces produced by these wires. Also, the
absence of nickel makes these wires useful in patients
Composition allergic to nickel. Ideal for situations where forces less
Titanium-79% than stainless steel and more than Ni- Ti alloy are
Molybdenum-ll% required.
Zirconium-{)6%
Tin-{)4% Adoantageous properties
1. High springback.

In these wires the metastable BCC structure of 2. High formability.
titanium is retained at room temperature by using a 3. Low modulus of elasticity.
variety of alloying additives like molybdenum, 4. Low load deflection rate.
vanadium and/or chromium. 5. Low stiffness.
6. Environmentally stable.
Distinctive features of this wire include-good 7. Excellent corrosion resistance.
springback, low force delivery levels, good formability 8. Can be joined by electrical resistance welding.
and weld ability. The process of ion implantation for

Material Used in Orthodontics-Introduction and Archwire Materials 335

Disadvantageous properties - 3 strands (Fig. 30.laC)
1. More friction than stain less steel or chrome-cobalt - 6 strands (Fig. 30.100), etc.
• Subclassification based on the mode of joining the
alloys. The friction can be decreased using the ion constituent strands-
implantation method where by titanium oxide and - braided (Fig. 30.lOE)
nitride are deposited on the wire to produce a - twisted (Fig. 30.lOF)
smoother finish.
2. Become brittle on overheating.

Weldability of B-titanium Wires Fig. 30.10A: Multi-stranded Fig. 30.10B: Multi-stranded
round wire (cut-section) rectangular wire (cut-section)
The wire "sets down" about 80% into the opposing
wire under electric resistance welding. The process
does not need to be reinforced.

Flat-to-flat electrodes are recommended along with
a light capacitance welding process.

ALPHA TITANIUM Fig. 30.10C: Three stranded Fig. 30.100: Multi-stranded
arch wire arch wire
Composition
Titanium-90%
Aluminium-Q6%
Vanadium-Q4%

L-_

This alloy is made up of closely packed hexagonal
crystals. This structure increases the number of slip
planes between the crystals, making the alloy more
ductile. Alpha titanium alloy wires are more stiff as
compared to nickel titanium wires.

TITANIUM NIOBIUM ALLOY Fig. 30.10E: Braided wire Fig. 30.10F: Twisted wire

This alloy was introduced to orthodontics in early Coaxial Archwire
1995, by Or Rohit Sachdeva.
Coaxial archwires are made of a central core wire of
Wires made of this alloy have less stiffness as 0.006 inch diameter wire with 5 or 6 outer wires (Fig.
compared to TMA wires resulting in an increase in 30.11).
the formability of the wire. The load deflection rate is
the same as TMA wires. These wires are more flexible and were very
frequently used for initial aligning of teeth before the
These wires are ideal as finishing wires as they can advent of Ni-Ti wires.
be bent more easily and still are able to maintain the
low force levels required. COMPOSITE/COATED WIRES

There is no leaching out of nickel from this alloy. These wires are made of a combination of materials
Canine to canine fixed retainers are also being coated one on top of another. The coating fibers include
manufactured from this alloy. fiberglass (Fig. 30.12)and ararnid. The candidate resins

MULTI-STRANDED ARCHWIRES

They are subclassified according to cross-section as:
• Round (Fig. 30.lOA)
• Rectangular (Fig. 30.lOB)
• Subclassification based on the number of

constituent strands

336 Textbook of Orthodontics

OPTIFLEX ARCHWIRES

Fig. 30.11: Coaxialwire These are composed of a silicon dioxide core which
provides the force or resiliency to the wire. The silicon
include polycarbonate and polyethylene terephthalate resin forms the middle layer. This adds strength to
glycol. For each fiber/resin system, there is a heating the wire and also protects the core from moisture. The
or working range where the material can be formed nylon outer layer makes the wire stain resistant and
or shaped without any degradation in its properties. also prevents it from damage. These wires are available
in the round as well as rectangular cross- sections and
are tooth colored, i.e. are more esthetic than other meta I
alloy wires. These wires provide light continuous
forces and are used during the initial aligning phase
of orthodontic treatment. To prevent permanent
deformation sharp bends should be avoided during
ligation to brackets.

All major types of wires have been discussed and
an effort has been made to provide information
regarding the clinical usage of the wires. Table 30.1
provides a comparison of the most frequently used
wires and the important characteristics of these wires.

PREFORMED AACHWIAES

4-;'-'Sb;o: Nil! Tooltt ,01"· Upper

Form: TNl!IIOrm

llf1i1•• i' 1

IlfOUU

C lJIPIft ••• ....."

McKC0I'F0_ 0'_

Fig. 30.12: A compositecoated wire

Table 30.1: Comparisonof compositionand desirable clinicalcharacteristicsof orthodonticwires

Wire type Spring Stiffness Forma- Stored Friction Biocompatibility Joinability
back and environ-
bility energy mental stability

Stainless steel Low High Good Low Low Good Soiderered and weldable
High Good Low Low to Good Soldereredt weldablef
Cobalt- Low
chromium Low moderate cc Not joinable

Nickel-titanium High Poor High Low to Good Welded
moderate Good Solderered and Weldabie
Beta-titanium Average Average Good Average
Multistranded High Low High High
Poor
Not known

f-blue and yellow eigiloy only
t-soldered with some difficulty
cosome corrosion and failure noted

Material Used in Orthodontics-Introduction and Archwire Materials 337

FURTHER READING 8. Kusy H..PG, reenberg AR. Comparison of clastic properties

1. Adarns DM, Powers]M, Asgar K: Effects of brackets and of Nickeltitanium and Betatitanium arch wires, Am J

ties on stiffness of an arch wire, Am J Orthod Dentofac Orthod Dentofacial Orthop 1982;82:199-205.
9. Kusy RP, Stevens LE.Triple stranded stain1esssteel wires-
Orthop 1987;91:131-36.
2. Burstone CJ, Goldberg AJ. Betatitanium new orthodontic evaluation of mechanical properties and comparison with
titanium alternatives, Angle Ortho 1987;57:18-32.
alloy, Am J Orthod Dentofacial Orthop 1980;77:121-33. 10. Kusy RP. A review of comtemporary archwires: their
3. Burstone Cl, Qin B,Morton IV: Chinese NiTi wire: a new properties and characteristics, Angle Ortho 1997;67:197-

orthodontic alloy, Am J Orthod 1985;87:445-52. 207.
11. Kusy RP: Comparison of nickel-titanium and beta-
4. Cobb NW Ill, Kula KS, Phillips C, Proffit WR. Efficiency
of multistrand steel, superelastic NiTi and ion-implanted titanium wire sizes tu conventional orthodontic arch wire
NiTi arch wires for initial alignment, CliJ1 Orthod Res materials, Am J Orthod 1981;79:625-29.
12. Kusy RP: The furture of orthodontic materials: the long
1998;1:12-19.
5. Grandhi RK, Combe EC and Speidel TM. Shear bond view, Am J Orthod Dentofac Orthop 1998;113:91-95.

strength of stainless steel orthodontic brackets with a 13. Miura F, Mogi M, Yoshiaki 0, et al. The super-clastic
property of the Japanese NiTi alloy wire for use in
moisture insensitive primer. Am J Orthod Dentofac
orthodontics, Am J Orthod 1986;90:1-10.
Orthop 2001;119:251-55.
6. Kapila 5, Sachdeva R. Mechanical properties and clinical 14. Stonert MM. Wire: clinical considerations. In Craber TM,
Swain BF (editors): Current orthodontic concepts and
applications of orthodontic wires, Am J Orthod Dentofac techniques, ed. 2, Philadelphia, ]975, W.B.5aunders.

Orthop 1989;96:100-9. 15. Waters NE. Superelastic nickel titanium wires, BritJ Ortho
7. Kusy RP, Dilley GJ, Whitley JQ: Mechanical properties of
]992;] 9:3] 9-22.
stainless steel orthodontic archwires, Clin Materia Is

1988;3:4] -59.

Bracket Material and
Auxiliary Force
Delivery Systems

Gurkeerat Slngh

• Brackets o Metal reinforced ceramic brackets
o Titanium brackets
o Classification
o Austenitic stainless steel • Bracket bases
o Polycarbonate brackets • Auxiliaryforce delivery systems
o Fibre-glass reinforced brackets
n Ceramic brackets o Eiastics and eiastic modules
o Springs
o Magnets in orthodontics

BRACKETS • Single wing
• Self-ligating, etc.
A bracket is defined as a device that projects horizontally to
support auxiliaries and is open on one side usually in the Technique for Which it is Used
vertical or horizontal.
• Begg light wire appliance
CLASSIFICATION • Edge-wise appliance
• Straight wire appliance
Brackets can be classified according to • Tip-edge appliance
• Lingual pre-adjusted edge-wise appliance, etc.
Material used in Manufacture
Slot Size of the Bracket
• Metal
• Plastic • 0.018" x 0.025"
• Polycarbonate • 0.022" x 0.028", etc.
• Fibre glass reinforced plastic
• Polyurethane Materials used for the manufacture of brackets
• Ceramic have seen a vast improvement in the past 25 years.
The esthctic needs of the patients have led to the ose
a. Alumina based: of materials other than metals in the manufacture of
- Monocrys talline brackets. Yet, the metal brackets are the most frequen-
- Polycrystalline tly used for routine treatment.
- Laminated brackets.
AUSTENITIC STAINLESS STEEL
b. Zirconia based brackets
• Titanium The most commonly used metal in the manufacture
of brackets is austenitic stainless steel or AISI 304 steel,
Morphology of the Bracket AISI standing for-American Iron and Steellnstitute.
The composition of AISI 304 (Table 31.1), has nickel 8
• Siamese percent and chromium 18 percent hence, is also called
• Mini-twin

Bracket Material and Auxiliary Force Delivery Systems 339

Table 31.1: Compositionof AISI304 steel

Fe 71 percent
Ni 08 percent
Cr ]8 percent
C < 0.2 percent

18-8 steel. These brackets are most frequently milled
from the metal (Fig. 31.1).

AISI 316 steel is used for the manufacture of
brackets using the casting technique. These brackets
are one piece brackets (Fig. 31.2), with no separate
mesh base; AISI 316 is too hard to be milled.

POLYCARBONATE BRACKETS Fig. 31.2: Single piece bracket, note the indentations
on the base (and, a lack of the usuallyseen mesh)
Polycarbonate brackets (Fig. 31.3) were described and
tested by Newman in 1969. These brackets got stained Fig. 31.3: A Begg polycarbonate(plastic)bracket
easily, rendering them unanesthetic. They distorted
easily and were..prone to fracture, particularly from
torsional forces or 'creep" under such forces. The
surface finish was poor and this led to an increased
friction in the appliance system. Polycarbonate
brackets with steel inserts were also introduced but
have not been clinically popular.

FIBER-GLASS REINFORCED BRACKETS

These brackets are basically polycarbonate, i.e.

approximately 60 percent, reinforced with fiber glass.

These fibers are about 2-3 mm in length and approxi-

mately 0.8 mm in diameter. The plastic conditioner is

methylmethacrylate monomer to dissolve the

polycarbonate base to enhance adhesion with the

adhesive. Clinically acceptable bonding strengths are

achieved when these are used as per the instructions

of the manufacturer, i.e. along with the primer

(Fig. 31.4).

Fig. 31.1: Metalbracket withmesh base Fig. 31.4: A fiber-glassreinforcedbracket
(brackets of two differentcompanies)

340 Textbook of Orthodontics

Fibre glass reinforced brackets' do not show any 2. Depending on their retentive mechanisms into:
tendency for fracture like ceramic bracket and do not a. Mechanical
pose any hazard in debonding. They can be debonded b. Chemical
like metal brackets. No enamel damage un Iike ceramic c. Combination-mechanochemical
brackets has been encountered during their
debonding. 3. Based on the material constituents into:
a. Pure ceramic
The only two disadvantages seen with these b. Laminated brackets.
brackets are-they tend to get worn off if in contact
with opposing teeth and they cannot be recycled 4. Based on the material constituent into:
satisfactorily. a. Alumina based
b. Zirconium based materials.

CERAMIC BRACKETS Advantages of ceramic brackets
1. The brackets are extremely esthetic. Ceramic
Advances in material sciences and the demand for
brackets are either transparent (monocrystalline)
more esthetic brackets led to the introduction of or opaque (polycrystalli.ne) which accounts for their
"invisibil ity".
brackets made of ceramic (Fig. 31.5). Ceramic brackets 2. They resist discoloration unlike polycarbonate
brackets.
were first introduced in 1987 and have practically 3. Marginal benefits include use in patients under-
going magnetic resonance imaging and also in
replaced most other type of esthetic brackets used patients who are allergic to nickel.

today. Disadvantages of ceramic brackets
1. Enamel abrasion of opposing teeth as in deep bite
The ceramic brackets developed initially had some
cases.
shortcomings; which included-excessive bond 2. Brittleness of the bracket material makes it more

strength (resulting in enamel fracture on debonding) prone to fracture.
3. High bond strength particularly with silane primed
brittleness of the bracket and surface finish (rough
ceramic bases leading to enamel fracture on
finish increases friction). These have been largely debonding.
4. Brittle, fracture of the bracket on debond ing makes
add ressed in the second generation of ceramic brackets debonding, technique sensitive.
5. Due to the inherent nature of the material accurate
and they rarely pose any problems now. bracket positioning is demanding.
6. High cost of the material.
Classification

Ceramic brackets may be classified based upon:
1. The crystal formation as:

a. Monocrystalline or
b. Polycrystalline brackets.

Fig. 31.5: A ceramic bracket with undercut Manufacturing process Monocrystalline brackets are
channels in the base manufactured from larger chunks of alumina called
"boules". These larger chunks or "boules" are cut
using diamond, rotary saws, laser and/or ultrasonic
methods. The manufacturing process itself leaves
behind surface roughness and micro cracks predis-
posing to the brittle nature of the bracket. These lead
to an increased surface roughness and the tendency
to fracture, frequently seen in the first generation of
ceramic brackets.

Polycrystalline brackets are manufactured by
sintering aluminium oxide with particle size of
approximately 0.3 microns. A binding materialis