AGE FACTORS IN ORTHODONTIC TREATMENT

AGE FACTORS IN ORTHODONTICS

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

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Dental changes with age
Skeletal changes with age
Soft tissue changes with age
Treatment options and age
Tooth movement and age


Along with the considerations of potential growth pattern of the
patient , it is important to consider the dental age , skeletal
age and emotional age of the individual relating to the
readiness for orthodontic treatment.
There is probably no more fundamental biologic principle
underlying orthodontic diagnosis and treatment planning than
this concept of biologic ages
A fundamentally correct treatment plan instituted at wrong
time can yield poor results.Thus for certain kinds of problems ,
treatment timing is probably the most critical decision that
orthodontist has to make


DENTAL CHANGES WITH AGE


Changes in dental occlusion with age
• From birth until adulthood and beyond , dental occlusion
undergoes significant changes
• It is important to understand and recognize the scope of
the changes that are normally occurring in the dentition
to be able to diagnose any abnormal developments and
prevent treating normal conditions in the mixed dentition
stage


• Stages of dental development
4 stages : 1.Gum pads
2.Primary dentition
3.Mixed dentition
4.Permanent dentition
• Normalcy in the dentofacial region differs from age to
age
• There are certain features in the developing dento facial
complex which are normal in a child , however when
present in an adult would constitute a malocclusion
• These are self correcting malocclusions or transient
malocclusions

• Some of the transient malocclusions are
1. Open bite seen in gum pads

2.Spacing in deciduous dentition

3.First deep bite www.indiandentalacademy.com

Transient malocclusions …….
4.Flush terminal plane

5.Ugly duckling stage

6.Second deep bite


Clinical considerations
• Diastema in early mixed dentition
stage
- Should be left untreated to avoid
impacting the permanent maxillary canine
- At early stages of dental development
the cusp tips of the erupting canines are
too close to the apices of the lateral
incisors - positioning the mesially inclined
roots of the incisors upright with the
orthodontic appliance could place the
lateral incisor roots in the path of eruption
of canine

- Might cause either the impaction of canines or the
resorption of root of lateral incisor

- Orthodontic treatment that involves such movements
should be postpone until the level of the cusp tip has
atleast passed beyond the apical third of the root of the
lateral incisor


• Molar relationship
- Cases with distal step in the

primary dentition stage –
treatment started soon
because condition will not self
correct with time

- Patient’s with flush terminal
plane relationship present a
more challenging question –
half of these cases progress
to normal class I relationship,
rest to either class II or end to
end occlusion

- These findings imply that what is considered normal
occlusion in primary or mixed dentition stage does not
necessarily lead to a normal occlusion in the permanent
dentition stage
- Therefore it is important for the clinician to closely
observe these cases and initiate orthodontic treatment at
the appropriate time


• TSALD
- Significantly increased from early adolescence until
early adulthood
- So,without long term retention ,adolescents who were
orthodontically treated to a perfectly aligned dentition
should expect some crowding to occur in the anterior
part of the dental arches
- Important clinical implications regarding long term
stability and retention of the treatment results
- The patient should be made aware of the probability of
these changes occurring after the retention appliances
have been discontinued

Dental arch changes with age
• Maxillary arch
- Intercanine width increases –

between 3 -13 yrs by 6mm

- Between13-45 yrs by 1.7mm
- Intermolar width – increases - between 3 -5yrs by 2 mm
- between 8-13 yrs by 2.2 mm
- decreases – by 1mm by 45 yrs of age
- There is a slight decrease in arch length with age because of
uprighting of the incisors


• Mandibular arch
- Intercanine width increases –

between 3 -13 yrs by 3.7mm

- Between13-45 yrs by 1. 2mm
- Intermolar width – increases - between 3 -5yrs by 1.5mm
- between 8-13 yrs by 1mm
- decreases – by 1mm by 45 yrs of age
- There is a slight decrease in arch length with age because of
uprighting of the incisors and loss of leeway space by the mesial
movement of the first permanent molars


Clinical considerations
• Following the eruption of mandibular central and lateral
incisors , the arch width measurements in the lower arch
are established
• Lower arch length may decrease with the loss of primary
molars and the mesial movement of first permanent
molars in the leeway space
• Because of these limitations ,most clinicians consider the
lower arch as the key to orthodontic diagnosis

 Dental changes in adolescence
upper molar
lower molar
Male
moved forward upright
Female

upright

moved forward

 Dental characteristics of aging
- Less upper incisor show and more lower incisor show at
rest and on smile.
- This is of great clinical importance because surgical
overintrusion of maxilla results in an esthetically disastrous
aging of the patient’s face


SKELETAL CHANGES WITH AGE


Maxillary complex
• Enlarges AP by deposition of
bone posteriorly at the
tuberosities, which also lengthens
the dental arch

• Forward growth - anterior
displacement as the bone is laid
down on its posterior aspect


• Downward growth - vertical
development of the alveolar
process, eruption of teeth and
inferior drift of the hard palate
• Lateral growth - displacement apart
of the two halves of the maxilla,with
the deposition of bone at the
midline suture
• Maxillary growth ceases on average
at about 15 yrs in girls and about 17
yrs in boys

Mandible
• Most mandibular growth occurs as
a result of periosteal activity
• Muscular processes develop at the
angles of the mandible and the
coronoids and the alveolar
processes develop vertically to
keep pace with the eruption of the
teeth
• As the mandible elongates with
growth at the condylar cartilage, its
anterior part is displaced
forwards ,while at the same time
periosteal remodelling maintains
its shape

• Bone is laid down on the posterior margin
of the vertical ramus and resorbed on the
anterior margin and this posterior drift of
the ramus allows lengthening of the
dental arch posteriorly
• At the same time the vertical ramus
becomes taller to accommodate the
increase in height of the alveolar
processes
• Lengthening of the mandible and anterior
remodelling together cause the chin to
become more prominent , an obvious
feature of facial maturation
• Mandibular growth ceases rather later
than maxillary growth , about 17 yrs in
girls and 19 yrs in boys

Growth rotations
• Growth rotations are most obvious and have their
greatest impact on mandible ,their effects on maxilla are
small and are almost completely masked by surface
remodelling
• Forward growth rotations are more common than
backward rotations
• Have both vertical and AP effects – correction of class II
malocclusion will be helped by a forward growth rotation
but made more difficult by a backward rotation
• Also have an effect on position of the lower labial
segment
• Thus growth rotations play an important role in the
etiology of certain malocclusions and must be taken into
account while planning orthodontic treatment

• The adolescent growth spurt in the mandible occurs in
less than 25% of the cases ,but the presence ,onset ,
duration and magnitude of the pubertal growth spurt in
facial dimensions cannot be accurately predicted for any
one individual

• Substantial mandibular growth occurs during
adolescence over a number of years .Therefore in the
presence of significant skeletal discrepancies , treatment
should not be postponed in anticipation of the elusive
spurt ,particularly if treatment is indicated at an earlier
age


• For individuals with unfavorable skeletal relationships ,it
is wiser to design a treatment plan with the assumption
that the same facial growth pattern will be maintained
during the treatment period.
• Orthodontists should be familiar with the effects of the
mechanics used on the facial and dental structures
therefore growth projections require careful attention to
the mechanics used


• In patient’s with a steep mandibular
plane , open bite tendency , long
anterior face ,and a class II
malocclusion at age 10 yrs ,the
probability is high that in most of these
cases a vertical growth pattern will
continue.
• so, orthopedic correction should
include the use of an extraoral
highpull force to the molars or any
other appropriate appliance that the
clinician prefers to use


• In patient’s with average skeletal discrepancy ,the
assumption will be that growth is going to proceed in an
unfavorable direction relative to the needed correction.
As treatment progresses , two possible outcomes may
occur :
- If the case improves as a result of favorable growth
and treatment changes,the clinician can modify the
mechanics accordingly
- If growth proceeds in an unfavorable direction ,the
mechanics are already designed with the eventuality in
mind


Growth modification for skeletal changes in the adolescent
Facial skeletal growth patterns in adolescents that often
are improved through orthodontics and growth
modification include
•Mandibular deficiency – redirection of skeletal growth
vectors with head gear,functional appliance have the
potential to improve mandibular projection and are often
combined with head gear


• Maxillary horizontal deficiency –
maxillary protraction and non
surgical advancement of the
maxilla
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Vertical maxillary excess –
vertically directed head gear , chin
cups ,bite block functional therapy

• Horizontal maxillary excess –
either through retardation of
anteroposterior growth through
head gear or through camouflage
via premolar extraction and
retraction of anterior teeth

Facial skeletal growth patterns in
adolescents that often are not easily
corrected by orthodontics and growth
modification include
• Mandibular prognathism
– Sutural growth of the maxilla is
more easily affected than the complex
growth characteristics of the mandible
- Application of chin cup force can
result in a down and back rotation of the
mandible, so chin cup therapy is
effective in cases with a short lower
facial height, contraindicated in long
face class III patients


• Vertical maxillary growth deficiency
- Any influence on this growth pattern is difficult and
there is little evidence that any growth modification
techniques that can significantly influence this growth
pattern are available
• Chin deficiency
- Relative improvement in chin projection may occur
with treatment designed to increase AP projection of the
mandible,but growth of the chin point itself is not affected
by orthodontic or orthopedic treatment


• The process of mandibular growth and remodeling is not
simply time-linked and the basis for changes in patterns
are not known.
• If temporal differences exist, they are not related directly
to dental age. The differences in pattern are large
enough to theoretically influence orthodontic treatment
outcomes.
• Therefore, treatments that are designed to influence
growth of the mandible must take into account whether
the mandible is growing in a more vertical or horizontal
direction during the therapeutic phase. If orthodontic
treatment plans are to be designed to “work with growth,”
then it is important to know both the direction and the
velocity of growth that is to be modulated.

• The mandibular remodeling has more variability during
periods of rapid growth.
• Treatment plans that concentrate on changing
mandibular growth could very well be more effective if
applied during a time in which growth is occurring with
more variation in the pattern.
(Age-related differences in mandibular ramus growth: a
histologic study Mark G. Hans, Donald H.Enlow, Regina
Noachtar. Angle Orthodontist 1995)


SOFT TISSUE CHANGES WITH AGE


Changes in lip length with growth
Vertical lip growth
• Subtelny – longtitudinal soft tissue changes upper and
lower lips , nose and soft tissue chin
Upper lip length ↑
↓
↑
↓

From 1-3yrs
Between 3-6 yrs
After 6 ( 6 – 15 )yrs
Slowly after 15 yrs

• Growth

curve is similar to that of general body
growth curve of Scammon


Lip separation
• Seen in growing adolescents
• Upper and lower lip grow more than skeletal
lower face
• Lower lip grow vertically than upper lip


Clinical importance
• Lip incompetence seen at 6 yrs , is self corrected at 16 yrs
• This is clinically significant b’coz :
» Esthetic effect
» Relation to the stability of overjet correction
• At ages 6-8 yrs – lip incompetence is due to short lips
( subjectively ) , but is actually due to incomplete soft tissue
growth
• Growth differential between lips and dentoskeletal components
is an advantage in treatment of unfavorable tooth to lips
relationship
• Vertical height has great influence on treatment outcomes
relative to resting lip posture , resting incisor relations , and
smile lines

• Mamandras studied lip growth
Females - Maxillary lip length completed at age
14 yrs
- Mandibular lip length completed at
age
of 16 yrs
Males - Maxillary and mandibular lip length
completed at 18 yrs
• Genecov
- between 7 – 17 yrs males have a greater
increase in upper lip length than females of the same age


Lip thickness
• Subtelny :
– Upper lip thickness increases from
ages 1 – 14 in both males and
females
– In males there is an increase in
thickness after 14 yrs of age

• Mamandras :

- upper lip in females – maximum

thickness at 14 yrs , thinning at 16 yrs
- upper lip in males – maximum thickness at
16 yrs , thinning thereafter
- lower lip in both males and females – growth
completed by 15 yrs

Clinical importance
• Extraction therapy on facial profile is more noticeable in
female patients than male patients
• Because lips do not thicken much during puberty in
females , any extraction treatment plan for females with
straight to convex profile should be considered with
caution
• In adolescent patients with marginal lip fullness
orthodontic placement of upper incisors becomes very
important ,this is because incisor retraction to decrease
the overjet will cause undesirable treatment outcome


Nasal growth
• Subtelny (1959 )
- downward and forward growth
of nose
- more vertically than A-P
- In males spurt is between 10
– 16 yrs
- In females , there is a steadier
growth curve and there is more
nasal growth than boys during
early adolescents
- In Angle’s class II there is
more pronounced elevation of the
bridge of the nose than in angle’s
class I

Nasal projection
• Males – greater rate of growth (from 12 – 17 yrs )
• Females – constant from age 12
Clinical importance
- Orthodontist evaluating class II female at age 12 –
expect minimal increase in nasal projection over the next
2 yrs
- In males , if upper lip retraction is done in combination
with expected nasal growth , will produce less than
optimal relationship between lips and nose


Chin
• Chin thickness – Genecov et al
- females greater than males – from ages 7-9 yrs
- males greater than females till 17 yrs
• Nanda –
- The increased projection of chin seen in females is
attributable to increased mandibular growth


Adulthood
• Behrent’s research
 Nasal changes
- increase in nasal projection
- nasal tip moved inferiorly
 Lip thickness
- upper lip tended to rotate down and back from the base
of the nose
- so , less maxillary incisor would be exposed on rest and
on smile
 Nasolabial changes
- With decrease in lip prominence and lowering of nasal
tip , the nasolabial angle becomes more acute

• Treatment planning decisions may be influenced by the
knowledge that soft tissue contour thickness will be
established by about age 16, but significant soft tissue
projection may still be expected on the basis of
continued skeletal growth.
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Treatment modalities involving extraction and/or surgery
should be influenced by the fact that there will be a
differential change in the soft tissue topography, with the
nose and chin areas exhibiting more growth relative to
the midface and nasal regions.

• The net perceptual effect of the midface flattening or
receeding within the facial complex is created by the
differential soft tissue movements rather than the
perceived result of orthodontic manipulations.

• It would appear that soft tissue profile changes are
caused by both skeletal movement and soft tissue
thickening.
• As nose and chin growth are expected to exceed lip
growth, allowances at the treatment planning stage for
this differential tendency may minimize any untoward
growth effects on the soft tissue profile.(Angle
Orthodontist 1997 No. 5, 373 - 380: Soft tissue profile
changes in late adolescent males Timothy F. Foley,
Peter G. Duncan.)


TREATMENT OPTIONS AND AGE


Treatment planning in the primary dentition
1. Reasons for treatment
- To remove obstacles to normal growth of the
face and dentition
- To maintain or restore normal function


2. Conditions that should be treated
- Anterior and posterior cross bites

- Cases in which primary teeth have
been lost and loss of arch space
may result


- Unduly retained primary incisors which
interfere with normal eruption of the
permanent incisors
- Malpositioned teeth which interfere with
normal occlusal function or induce faulty
patterns of mandibular closure
- All habits or malfunctions which may distort
growth

3. Conditions that may be treated

- Distoclusions that are atleast partly positional.Occlusal
equilibration or tooth movements may restore normal
function , the rest of the problem may be treated at this
time or later

- Certain distoclusions of a skeletal nature are best
treated at this age , but the patient must be socially
mature and the cases must be carefully chosen
- Open bite due to tongue thrusting or digital sucking habit


4.Contraindication to treatment in the primary dentition

- when there is no assurance that the results will be
sustained
- when a better result can be achieved with less effort at
another time
- when social immaturity of the child makes treatment
impractical


Treatment planning in the transitional
dentition
1.

Reasons for treatment
- To remove obstacles to normal growth of the face and
dentition
- When the malocclusion cannot be treated more
efficiently in the permanent dentition

2. Conditions that should be treated
- Loss of primary teeth endangering the available space
in the arch
- Closure of space due to premature loss of primary
teeth
- Crossbites of permanent teeth
- Supernumerary teeth that may cause malocclusion
- Class II cases of functional , dental and skeletal type
- Space supervision problems

3. Conditions that may be treated

- Class II malocclusion of skeletal type
- Class III malocclusion where early treatment is
possible
- All malocclusions accompanied by extremely
large teeth . If serial extractions are to be
undertaken , treatment must be instituted in the
mixed dentition
- Gross inadequacies or disharmonies of the apical
base


Serial extraction procedures
• when properly executed, will result in self-correction or
prevention of the development of irregularities in the
incisal segments of both maxillary and mandibular
dentures.


• Such procedures, excluding the existence of abnormal
tongue and swallowing habits, will permit the mandibular
incisors to tip and move lingually to positions of
functional balance, thus giving the orthodontist a
valuable clue to the correct location and inclinations of
these teeth.
• If such information is recorded and the positions and
inclinations of the mandibular incisors maintained until
the conclusion of orthodontic treatment, little difficulty will
be experienced during the retention period.
–Charles H. Tweed, 1966
(Angle Orthodontist, 1990: Serial extraction of first
premolars – postretention evaluation of stability and
relapse Robert M. Little, Richard A...)

Maxillary expansion
• Expansion of the maxillary arch is the most common
treatment intervention to correct posterior cross bite ,and
the treatment approach is related to the age of the
patient
• Before the mid palatine suture fusion orthopedic forces
may be applied to separate the suture and allow the
bone to fill in the expanded midpalatine area


• Once the suture closes , at about 16 yrs of age ,a
decline in the ability of rapid palatal expansion occurs as
a result of the progressive interdigitation and fusion of
the various sutures as well as the resistance of the
skeletal and soft tissue structures , which in turn become
less responsive to the expansion forces
• Although , it is relatively easy to widen the maxilla by
opening the mid palatal suture during adolescence , it
becomes gradually more difficult during late adolescence
• As a result , the effectiveness of RME decreases and
after 16 yrs of age is usually not recommended


Surgically assisted expansion
• The ability to increase the skeletal transverse
dimension in the adults may be accomplished
with a surgically assisted rapid palatal expansion
or during orthognathic surgery when a two or
three piece maxillary osteotomy widens the
maxilla


Adolescent treatment
1.

General characteristics of adolescent malocclusion

- Dentition and occlusal relationships are established
- Skeletal growth may be mostly over and decelerating
- Muscle function is matured
- Functional malocclusions are less frequent since they
have largely been accommodated by dentoalveolar ,
skeletal , or mandibular joint adaptations


2. Advantages of adolescent treatment
- Control of all permanent teeth except third molars is now
possible
- It is beneficial to treat when bone turnover rates are still high
though adult dimensions are nearly achieved
- Motivation for treatment is high , especially when facial
esthetics are affected
- Since treatment is less dictated by developmental events ,
treatment options are lessened


3.Some difficulties in adolescent treatment
- The best opportunities for control and manipulation of
severe skeletal dysplasia are past
- Sports and social activities so important to adolescent ,
often compete with plans for orthodontic treatment
- The time necessary for treatment may be longer for
certain malocclusions
- Tooth positioning is often more difficult when the
occlusion is fully established and root formation is
complete than was tooth guidance during eruption


Adult orthodontics
• When treating adults orthodontist needs to be prepared
to do the following
- Diagnose different stages of periodontal disease and
their associated risk factors
- Diagnose TMJ dysfunction before , during , after tooth
movement
- Determine which cases require surgical management
and which ones require incisor reangulation to
camouflage the skeletal base discrepancy
- Work cooperatively with a team of other specialists to
give the patient the best outcome

Indications
• To improve tooth - periodontal relationship
• To establish an improved plane of occlusion in order to
distribute forces through the broadest area possible
• To balance the existing space between teeth for better
prosthetic replacement
• To improve spaces to provide for normal tooth to tooth
contact
• To improve occlusion and coordination with the
masticatory muscles and TMJ
• To satisfy the esthetic desires of the patient


Contra indications
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Severe skeletal discrepancies
Advanced local or systemic disease
Excessive alveolar bone loss
Inability to obtain a satisfactory result
Poor stability prognosis
Lack of patient motivation


• Mandibular skeletal problem in pre adolescent
child –
 AP direction
- Excess – orthopedic posterior force (chin cup )

- Deficiency - orthopedic anterior force (functional
appliances )


 Vertical direction
- Excess - orthopedic vertical maxillary force ( vertical
pull chin cup + bite block )

- Deficiency – Appliance to increase the vertical alveolar
development ( bite plane )


• Mandibular skeletal problem in non growing
patients
 AP direction
- Excess – mild - camouflage
- severe – surgical mandibular set back
- Deficiency - mild - camouflage
- severe – surgical mandibular advancement


- Excess - mild - camouflage
- severe – surgical height reduction
- severe – surgical height increase


• Maxillary skeletal problem in pre
adolescent child –
 AP direction
- Excess – orthopedic posterior force
(head gear )
- Deficiency - orthopedic anterior force
( reverse pull head gear )


- Excess - orthopedic vertical maxillary force ( high pull
head gear )
- Deficiency – Appliance to increase the vertical alveolar
development (functional appliance )


• Maxillary skeletal problem in non growing
patients
 AP direction
- Excess – mild - camouflage
- severe – surgical maxillary set back
- severe – surgical maxillary advancement
- Excess - mild - camouflage
- severe – surgical maxillary impaction
- severe – surgical maxillary inferior position

Factors in the selection of the orthodontic
treatment plan
Adolescent
EXISTING ORAL PATHOSIS
Dental caries
More likely to have simple limited
caries lesions, but more
susceptible to caries
Periodontal disease
More resistant to bone loss , but
highly susceptible to gingival
inflammation
Faulty restorations
Few significant restorative
problems
TMJ
Small percentage with symptoms ,
because of high degree of TMJ
adaptability

Adult

More likely to have recurrent decay
, restorative failures , root decay
and pulpal pathosis
High susceptibility to periodontal
bone loss

Frequent restorative problems with
economic and treatment planning
implications
Frequent appearance of symptoms
with dysfunction


Adolescent

Adult

Dentofacial esthetics
Reasonable concern , frequently
matched to severity of condition
Occlusal awareness
Infrequent cause of problem

SKELETAL RELATIONSHIPS
Because of growth , an orthopedic
treatment option available , stable
correction of skeletal
discrepancies possible , vertical
corrections most difficult , AP next
and transverse least
BIOLOGIC CONSIDERATIONS
Significant neuromuscular
adaptability , allowing variety of
biomechanical choices

Concern occasionally
disproportionate to degree of
existing pathosis
Heightened;may lead to accelerated
enamel wear with adverse change
in supporting tissue
No growth , surgical changes
necessary for moderate to severe
skeletal disharmonies ,orthodontic
correction of skeletal transverse
problems most difficult , AP
problems somewhat less and
vertical problems least
Mechanical options limited because
of lack of neuromuscular ability


Adolescent

Adult

•

Growth is a positive factor in the
resolution of many adolescent
malocclusions

No growth is present , so potential for
significant skeletal alterations without
orthognathic procedures is minimized

•

Rate of tooth movement
Predictable and rapid, particularly
during eruptive stages when
permanent root development is
not yet completed

Initially somewhat slower , but more
rapid and predictable once initial
movement has begun

THERAPEUTIC APPROACHES
AVAILABLE
Tooth movement
Most require some tooth moving force
Most require some tooth moving
force
Orthopedics
Effective in only small percent
About half require this

Adolescent

Adult

Functional appliances
Benefit possible in 20 % - 30 %
Orthognathic surgery
Major skeletal alterations
needed in 1%-5%
EXTRACTION VERSUS NON
EXTRACTION THERAPY
Four premolar extraction more
frequent to resolve crowding
symmetrically

Small percent benefit

Alterations needed in 10%50%

Four premolar extraction less
frequent to resolve crowding ,
upper premolar extraction ,
asymmetric extraction and
lower incisor extraction ,
stripping of over bulked
restoration are more common


Adult

Adolescent
ANCHORAGE REQUIREMENTS

More frequent incorporation of
headgear to maximize
anchorage and the retraction
of anterior teeth

Greater anchorage potential
because of completely erupted
1st and 2nd molars,in addition
accentuated mesial drift ,
particularly in the mandibular
arch means that fewer adult
cases will be categorized as
maximum anchorage problems


Factors affecting patient’s acceptance of the
orthodontic treatment plan
Adolescent
•

Adult

Duration of treatment
Usually not of concern;2-21/2 yrs
in orthodontic appliance is handled
quite easily by most adolescents

•

Cost of treatment
Insurance may cover cost,
parents frequently will make
sacrifices to accommodate their
child’s need

Adults are much more cognizant of
the duration of treatment and may
assume something is going wrong
if they are not finished at projected
time
Adult orthodontics not covered by
insurance, so orthodontist must be
sensitive to these factors,so
patients will receive optimal
treatment and not be “turned off”
to quality dental care


Adolescent
•

Adult

Perceived risk / benefit ratio
Greater sense of benefits
compared to minimal risks

Must be assessed by the
orthodontist and honestly
discussed with the
patient,explanations given to the
patient about the responsibilities
during treatment , especially
periodontal maintainence and
more frequent recall to the
hygienist while in appliance


TOOTH MOVEMENT AND AGE


Tipping
• The adult supporting structures react
somewhat differently when compared to
the young tissues because the anatomic
environment in the adults is different
• The periodontal structures , particularly
the labial and lingual bony plates are
composed of a dense lamellated bone
tissue with relatively small marrow
spaces,Spongy bone exists in the
interseptal areas
• So,tooth movement in a MD direction
within the “alveolar trough”is more
favorable than in a labiolingual direction

• Along the inner bone surface of adults ,a series of darkly
stained resting lines are seen ,indicating that only minor
tissue changes have occurred over a long time
• The root exhibits a thick layer of cementum and strong
apical fibres
• The apical third of the root is more firmly anchored in
adults than in young patients
• Hence , when an adult tooth is tipped over a short
distance there is comparatively little tooth movement of
the apical third of the root
• On the other hand , if the tipping is prolonged , the tooth
will begin to act as a two – armed lever
• There may be apical resorption and destruction of
alveolar bone wall as well

Extrusion
• Successful extrusion of teeth is largely dependent on
whether the treatment is performed during favorable
growth period
• Extrusion in a mass movement may result in complete
and permanent closure of the bite provided the
treatment is performed shortly after the eruption of the
teeth
• Such a favorable result is due to the readiness by
which the supporting tissues of young persons are
transformed and rearranged after tooth movement


• After the age of 18 – 20 yrs there is less
growth activity
• The pdl fiber bundles will become stretched
after extrusion , but are less readily
elongated and rearranged
• There is also a tendency for more distant
fibers along the alveolar crest to stretch
• Extrusion of adult teeth in a mass movement
may thus result in relapse after displacement
and subsequent contraction of the whole
gingival fiber system
• In such cases , closure of an open bite may
be performed with greater success if front
teeth are extruded individually and not in a
mass movement

Intrusion
• Some practitioners state that intrusion of
adult teeth cannot be undertaken without a
corresponding shortening of the apices by
root resorption
• If carefully measured forces are applied ,
there will be less tendency for such
shortening of roots
• Stabilisation of tooth position after intrusion
of adult teeth can be attained only by
establishing a correct MD relationship
between the dental arches


Timing of surgical treatment
• Early jaw surgery has little inhibitory effect on further
growth
• Actively growing patient’s with mandibular
prognathism can be expected to outgrow surgical
correction and require retreatment
• So , the correction of mandibular growth must be
delayed until the late teens


• In contrast to mandibular set back , mandibular
advancement at age 14 – 15 is quite feasible

• Maxillary advancement should be delayed until
the early adolescent growth spurt unless there
are preponderant psycological considerations


Biomechanical considerations
• In an adult patient the amount of bone support of each
tooth is an important consideration
• When bone has been lost ,the Pdl area decreases,and
the same force against the crown produces greater
pressure in the Pdl of a periodontally compromised
tooth than a normally supported one
• The absolute magnitude of force used to move teeth
must be reduced , to prevent damage to the Pdl ,bone ,
cementum and root
• The greater the loss of attachment,the smaller the area
of supported root and the further apical the center of
resistance will become

• The magnitude of tipping moment produced by a force is
equal to the force times the distance from the point of force
application to the center of resistance
• Orthodontic force must be applied to the crown of a tooth,
and the further the point of force application is from the
COR,the greater will be the tipping moment produced by
any given force


Age related changes in periodontal ligament
• The number of adult patients in most clinical orthodontic
practices has increased in recent years. Because
orthopedic jaw control through growth is impossible in
adult patients and periodontal disease is more
likely,orthodontic tooth movement is more complex in
adults than in adolescents.
• In particular, adults who have periodontal problems risk
permanent damage to the periodontal tissues
• The periodontal ligament (PDL), plays a significant role
in bone remodeling at the PDL-alveolar bone interface
during tooth movement.

• Proliferative activity of fibroblast-like cells in the PDL
decreases with age, and faster or more efficient
tooth movement can be achieved in younger
individuals
(AO1997 Influences of aging changes in proliferative
rate of PDL cells during experimental tooth
movement in rats Shingo Kyo)


Age related bone changes
• Orthodontic tooth movement as a result of bone
modeling and remodeling also depends greatly on age
related changes of the skeleton
• Cortical bone becomes more dense while the spongeous
bone reduces with age and the structure changes from
that of a honeycomb to a network


The biologic background for orthodontic tooth movement in
adults indicates that
1.The forces used in adults should be at a lower level than
those used in children
2.The initial forces should be kept low because the
immediate pool of cells available for bone resorption is
low
3.The moment – to – force ratio should be increased
according to the periodontal status of the individual teeth
4.With increasing marginal bone loss , light continuous
intrusive force should be maintained during tooth
displacement


Retention
• The amount of growth remaining after orthodontic
treatment will obviously depend on the age , sex , and
relative maturity of the patient
• After growth modification treatments ,post treatment
rebound is likely ,with more growth of the upper than the
lower jaw
• Relapse tendency controlled in 2 ways
- To continue head gear on the upper molar on a
reduced basis
- Functional appliance of the activator – bionator type to
hold tooth position and the occlusal relationship

• Adult patient’s should be brought to their final orthodontic
relationship with archwires and then stabilized with
immediately placed retainers before eventual detailing of
occlusal relationship by equilibration

• A suckdown plastic wafer is the best choice immediately
upon removing the orthodontic appliance


Conclusion
• Don’t disturb transient malocclusions.
• Attempts at orthopedic change to be timed…to maximize
the growth potential of the patient.
• Class II malocclusions due to mandibular deficiencies
and class III malocclusions due to a deficient maxilla are
treatable…when treatment is undertaken or properly
timed.
• Although the periodontal and alveolar support is
generally weaker…adult patient can be treated through
alterations in the bio-mechanical approach.


References
• Orthodontics – current principles and techniques – Graber and
Vanarsdall
• Orthodontics – current principles and techniques – Graber and
Swain
• Textbook of orthodontics – Samir.E .Bishara
• Orthodontics – Principles and practice – T.M.Graber
• Contemporary orthodontics – William.R.Profitt
• Orthodontic and orthopaedic treatment in mixed dentition –
- Mc Namara and Brudon
• Biomechanics in clinical orthodontics – Ravindra Nanda
• Handbook of facial growth – Enlow
• Esthetic orthodontics and orthognathic surgery –
- David.M.Sarver

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