ADULT ORTHODONTICS Introduction History In 1880 Kingsley, after treating a 40 year old patient for anterior cross-bite stated, “It may be regarded as settled that there are hardly any limits to the age when movement of teeth might not succeed”. But he maintained, “The action is slower, growing more and more difficult and in cases where a considerable number of teeth are to be moved, the results become more and more doubtful with advancing years”. In 1901 Mac Dowell wrote, “After the age of 16 years, a complete and permanent change in transition of occlusion the author believes to be almost impossible. There may be a case or two of rare exceptions but as a rule the change cannot be accomplished successfully owing to the development of the adult glenoid 1
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ADULT ORTHODONTICS
Introduction
History
In 1880 Kingsley, after treating a 40 year old patient for
anterior cross-bite stated, “It may be regarded as settled that
there are hardly any limits to the age when movement of teeth
might not succeed”.
But he maintained, “The action is slower, growing more and
more difficult and in cases where a considerable number of teeth
are to be moved, the results become more and more doubtful with
advancing years”.
In 1901 Mac Dowell wrote, “After the age of 16 years, a
complete and permanent change in transition of occlusion the
author believes to be almost impossible. There may be a case or
two of rare exceptions but as a rule the change cannot be
accomplished successfully owing to the development of the adult
glenoid fossa and the density of the bones and muscles of
mastication”.
In 1912 Lischer summarized, “Recent experiences of many
practitioners have ------ us to a better appreciation of the ‘golden
age of treatment’, but that we mean that time in an individual’s
life when a change form the temporary to permanent dentition
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takes place. This covers the period form the sixth to the 14 t h
year”.
In 1921 Case demonstrated an efficient space closure, for a
patient with pyorrhea in the lower anterior area. However, in the
past 3 decades, a major reorientation of orthodontic thinking has
takes place. The following are some of the reasons for the
increased interest by the orthodontics in adult patients, as well as
several causes for increased interest shown by adults in
orthodontic treatment
Improved appliance placement techniques
More successful management of TMJ joint symptoms
Effective management of skeletal jaw dysplasias using
advanced orthognathic surgical techniques
Reduced vulnerability to periodontal breakdown as a result
of improved tooth relationship and occlusal function
ADULT ORTHODONTIC TREATMENT OBJECTIVES
1. Parallelism of abutments
The abutment teeth must be placed parallel with the other
teeth to permit insertion of multiple unit replacements. A
restoration will have a better prognosis when the abutments are
parallel before tooth preparation, as it facilitates the transfer of
masticatory forces along the long axis of the tooth.
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2. Most favorable distribution of teeth
The teeth should be distributed evenly for replacement of
fixed and reasonable prosthetic in the individual arches.
3. Adequate embrasure space and proper root position
The anatomic relationship of the roots is important in the
pathogenesis of periodontal disease. Creation of adequate
embrasure space and proper root position allows for better
periodontal health, especially when the placement of restoration
is necessary.
4. Better lip competency and support
When adequate support is not given to the upper lip by the
upper incisors, it may create a change in the anteroposterior and
vertical positioning of the upper lip and increases wrinkling.
This often makes the face prematurely aged and is a major
concern for adults especially women, who are usually anxious
about changes in upper lip.
In cases requiring anterior restorations, retraction is
recommended to achieve lip competency while maintaining lip
support.
5. Improved crown/root ratio
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6. Improvement or correction of mucogingival and osseous
defects
Proper repositioning of the prominent teeth in the arch
which improves gingival topography.
ADJUNCTIVE ORTHODONTIC THERAPY (6 months
maximum)
By definition, adjunctive orthodontic treatment refers to the
tooth movement carried out to facilitate other dental procedures
to control disease and restore function.
(E.g.) Congenital absence of II premolar with mesial
migration of first molar. An orthodontist distalises the first
permanent molar to replace a satisfactory pontic in second
premolar area.
Physiologic occlusion
Physiologic occlusion, although not necessarily an ideal or
class I occlusion is one that adapts to the stresses of function and
can be maintained indefinitely.
Pathologic occlusion
It is one which cannot function with contributing to its own
destruction. A pathologic occlusion may manifest itself by any
combination of
Excessive wear of the teeth with sufficient compensatory
mechanisms.
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Temporomandibular pain/dysfunction
Pulpal changes ranging from hyperemia to necrosis
Periodontal damage
For example, when a tooth is lost the adjacent teeth tend to
drift, tip and rotate. Whether this requires orthodontic correction
will depend upon whether the sings of pathologic occlusion are
present. If the patient can still maintain adequate plaque control
and if the occlusal forces are within the physiologic tolerance of
the support mechanism, and if the patient can function with
prematurities or functional shifts, then the occlusion may be
considered physiologic and the only indication for orthodontic
treatment could be the patient desire for improved esthetics.
Goals of adjunctive treatment
Facilitate restorative treatment by repositioning the teeth in
ideal positions.
Improve the periodontal health by eliminating plaque
harboring areas.
Establish favorable crown to root ratios
Position the teeth so that occlusal forces are transmitted
along the long axis of teeth
Principles of adjunctive orthodontic treatment
1. Diagnostic and treatment planning considerations
Planning for adjunctive treatment requires two steps
Collecting an adequate database
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Developing a clearly stated list of the patient problems
taking care not to focus unduly on any one aspect of the
complex situation.
The patients motivation for and expectations of treatment,
general dental awareness, enthusiasm for the proposed treatment
and ability to cooperate with the treatment regimen all must be
evaluated.
Diagnostic records
Records usually include individual intra-oral radiographs to
supplement the panoramic films that usually supplies for
younger and healthier patients.
Pre-treatment cephalometric radiographs are usually not
required
Dental casts obtained from fully intended impressions
should be acquired.
Once all the problems have been identified and categorized,
special attention must then be turned to tooth positions that
require modification. The key treatment planning question is –
can the occlusion be restored within the existing tooth positions
or must some teeth be moved to achieve a satisfactory, stable,
healthy and esthetic result? The goal of adjunctive treatment is to
produce physiologic occlusion and facilitate other dental
treatment and has little to do with the angles concept of ideal
class I tooth relation.
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As a general guideline, adjunctive orthodontic treatment
that would take more than 6 months should be avoided as it
clearly indicates a need for comprehensive orthodontic treatment
involving all the teeth.
Biomechanical considerations
In adults, the absolute magnitude of forces used to move
teeth must be reduced when periodontal support has been lost, to
prevent damage to periodontal, bone, cementum and root. In
addition, the smaller the area of supported root and farther the
CRes of the tooth.
CRes of a single rooted tooth is at approximately 6/10 t h the
distance between the root apex and the alveolar crest, from the
root apex. Apical relocation of the C Res increases the magnitude
of the tipping moment (M), for a given tone and consequently a
large countervailing couple (M) would be necessary to effect
bodily movement.
The recommended brackets for adjunctive treatment is 22
slot-edgewise brackets because rectangular slot permits control
of buccolingual axial inclination, the wider brackets permit
control of rotations and tipping.
Removable appliances can be used in situations where a
number of teeth are missing. They permit the reaction forces to
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be spread over adjacent supporting tissues such as the palatal
vault, alveolar mucosa as well as the anchor teeth.
If many teeth are missing, this approach may be the only
way to generate anchorage.
Bracket placement when placing a partial fixed
appliances for adjunctive treatment, the brackets are placed in
the ideal positions only on teeth to be moved and the remaining
teeth to be incorporated in the anchor system are bracketed in the
most convenient way possible, with the arch wire slots closely
aligned. Passive engagement of wires to anchor teeth produces
minimal disturbance of teeth that are in a physiologically
satisfactory position.
3. Timing and sequence of treatment
After the development of a treatment plan the first step is
the control of nay active dental disease.
Periodontal management before any orthodontic
treatment, destructive periodontal disease must be controlled,
because orthodontic tooth movement superimposed on poorly
controlled periodontal health can lead to rapid and irreversible
breakdown of the periodontal support apparatus. And also
periodontal therapy should be continued even after orthodontic
treatment is started. Scaling, curettage and gingival grafts should
be undertaken, before any tooth movement is done. Clinical
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studies have shown that orthodontic treatment of adults with
compromised periodontal tissues can be completed without loss
of attachment, provided there is good periodontal therapy both
initially and during tooth movement. Surgical pocket elimination
and osseous surgery should be delayed until completion of
orthodontic phase, because a significant amount of soft tissue
and bone recontouring occurs during orthodontic tooth
movement.
Endodontic treatment before any tooth movement, active
caries and pulpal pathology must be eliminated. Tooth should be
restored with well placed amalgams and composite resins.
Crown, bridges and other restorations requiring detailed occlusal
anatomy should not be placed until any adjacent, treatment has
been completed, because the occlusal relationship will inevitably
be changed by orthodontic tooth movement.
ADJUNCTIVE TREATMENT PROCEDURES
1. Uprighting posterior teeth
When planning molar uprighting, a number of inter-related
questions must be answered. The first is that, if the third molar is
present, whether both the second and third molar is present,
whether both the second and third molars should be uprighted.
For many patients, distal tipping of the third molars, places them
in such situations where plaque control is a problem or the molar
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is not in functional occlusion. In such situations, it is ideal to
extract the third molars and upright the second molars alone.
The second question is, whether to upright the tipped teeth
by distal crown tipping that would increases the space available
for a later pontic or by a mesial root movement, which would
maintain reduce or even close the edentulous span. This decision
is influenced by
Position of the opposing tooth and the desired occlusion
The anchorage available for such movements
Most importantly the contour of the bone in the edentulous
ridge. If extensive ridge resorption has occurred especially
in the B-L direction, mesial movement of a wide molar root
will occur very slowly and may lead to the development of
dehiscence on the buccal and lingual sides.
In general, distal crown tipping is preferred than mesial
root movement for uprighting molars.
The third question is whether slight extrusion of the tooth
is permissible or maintenance of the existing occlusal height is
required. Tipping the tooth distally generally extrudes it. If the
crown height is systemically reduced as uprighting proceeds, the
ultimate crown-root ratio is improved. Unless slight extrusion of
crown is acceptable, the patient should be considered to have
problems that require comprehensive treatment and treated
accordingly.
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Appliances for molar uprighting
Each appliance can be separated into an active and a
reactive (stabilizing or anchor) unit. To provide appropriable
anchorage, canine to canine should be included and linked by a
heavy statistically lingual arch. This arch decreases the buccal
displacement of anchor teeth. This is mandatory in the
mandibular arch and advisable in the maxillary arch.
Distal crown tipping with occlusal antagonist
Initial alignment 17 x 25 braided SS/17x25 A-NiTi
provided the wire can be placed in the brackets with permanent
distortion and the occlusal contacts are not too heavy, molar
uprighting will begin and a single wire may complete the
necessary uprighting.
From the placement of the wire, it is always necessary to
relieve occlusal contacts against the molar. Failure to relieve
may prevent it from uprighting and may cause excessive tooth
mobility.
If molar severely tipped, continuous wire that uprights the
molar will also tip the premolar. To avoid this sectional spring is
used where the anchor segment is stabilized with 19x25 SS and
an auxiliary spring is placed in the auxiliary tube. The uprighting
spring 17 x 25 TMA with a helical loop 17 x 25 SS with
helical loop decrease the force.
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The mesial arm of the spring should lie passively in the
vestibule and upon activation should hook over the a. wire in
stabilizing segment. It is important to see that there is sufficient
space for the arm to slide distally when the molar uprights.
As this method causes extrusion along with distal tipping, it
should be used only in situations where there is an occlusal
antagonist.
Uprighting without extrusion
If the molar has no antagonist, if extrusion is undesirable or
if the crown is to be maintained in the same position while the
roots are being brought forward an alternative uprighting spring
should be used.
Initial alignment flexible wire
Single T-loop sectional arch-wire 17 x 25 ss/19 x 25 TMA
is adapted to fit passively in anchor units and gabled at the T to
exert an uprighting force.
If the edentulous span is intended to be closed, the distal
end of the T-loop is pulled distally to open the loop by 1 – 2mm.
This produces a mesial force on the molar that counteracts the
distal crown tipping while the tooth uprights by mesial root
movement.
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Final positioning of molar and premolars
Once the uprighting of molars has been accomplished, it
often is desirable to increase the available space for the pontic.
This is done by using a relatively stiff base a wire (in a 0.022
slot, 18 mil round / 17 x 25 SS) and as open coil spring is placed,
which when comprised exerts a force of 100 gms, to move the
premolars mesially while continuing to tip the molar distally.
Potential problems in Molar Uprighting
Excessive mobility of teeth being moved may be because
increased force / failure to remove occlusal contacts. Care should
be taken to avoid excessive crown reduction, it may be helpful to
use a bite splint on the opposing arch.
In general, failure to upright the teeth usually results from
occlusal interferences rather than insufficient force.
Retention
After molar uprighting, the teeth are in an unstable position
until the fixed or removable appliances that provide long term
stability is used. Long delays is taking the final prosthesis should
be avoided. For nearly all patients, before placement of
prosthesis, an intermediate form of splinting is necessary to
maintain the position of the abutment teeth. Two methods of
intermediate splitting -
1. Extracoronal splinting
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19 x 25 SS or 21 x 25 TMA was designed to fit the brackets
passively will prevent any tooth movement. This type of
retention should not be used for long periods because orthodontic
appliances themselves make effective oral hygiene maintenance
difficult.
2. Intracoronal splinting
The preferred approach to intermediate splinting is an
intracoronal wire splinting – shallow cavities may be prepared in
the abutment teeth and a splint of 19 x 25 SS - intracoronally
with either amalgam or composite resins. As a general rule, a
fixed bridge can be placed within 6 weeks after the orthodontic
appliance is removed.
Forced eruption
Indications
Teeth with defects in the cervical third of the teeth
Teeth with one or two vertical periodontal defects
To obtain good accepts for endodontic and restorative
procedures or to reduce pocket depth it would be necessary to
perform crown lengthening. However, surgery causes sacrifice of
surrounding bone. Extruding the tooth orthodontically improves
endodontic access and also allows placement of crown margins
on sound tooth structure.
Factors considered in treatment planning
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Before beginning treatment, it is essential to have a
periapical radiograph to know the vertical extent of the defect,
the periodontal support, the root morphology and position. The
ideal morphology is a single tapering root. Flared or divergent
roots will increase the root proximity with extrusion. The
occlusion should also be examined to make sure that sufficient
space still exists in relation to the opposing arch, to permit the
placement of a satisfactory restoration.
A final consideration is the crown-root ratio at the end of
treatment, which should be 1:1 or better. The length of time
required for forced eruption depends on
The age of the patient
The distance the tooth has to be moved
Viability of the periodontal
Rate
In general extrusion can be as rapid as 1mm/week without
damage to the periodontal (so 3 – 6 weeks is sufficient for almost
any patient).
Technique
Since extrusion is the tooth movement that occurs most
readily and intrusion the movement that occurs least , sample
anchorage is usually available from adjacent teeth. The appliance
needs to be quite rigid ones the anchor teeth and flexible where it
attaches to the tooth to be extruded. This except contraindicates
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the use of a continuous a. wire which would produce the desired
extrusion but also lips the adjacent teeth toward the tooth being
extruded reducing the spaces.
Two appliances
T-loop 17 x 25 s.s / 19 x 25 Ti. Brackets should be
positioned as gingivally as possible on the tooth to be
extruded and incisally on the anchor teeth. The part of the
wire that gets attached to the tooth to be extruded should be
--- occlusal that the wire engaging the anchor segment. The
left of the T-loop is limited by the depth of the vestibule.
Heavy stabilizing arch wire (19 x 25 SS) bonded directly to
the facial surface of the adjacent teeth
A post and core with temporary crown and pin is placed on
the tooth to be extruded and an elastomeric module is used to
extrude the tooth. This appliance is simple, provides excellent
control of anchor teeth, but the control of the tooth being
extruded is not as precise it is with bonded brackets.
With either of these, the patient must be seen every 1 –
2weeks for occlusal reduction to control inflammation and to
monitor progress. After active tooth movement, the tooth should
be stabilized with a passive arch wire or by tying the pin to the