Bio mechanical considerations of Open bite. Dr. Ajay

11
BIO - MECHANICALBIO - MECHANICAL
CONSIDERATIONS IN OPEN BITECONSIDERATIONS IN OPEN BITE
Dr. AJAY SRINIVASDr. AJAY SRINIVAS
PG STUDENTPG STUDENT

INTRODUCTIONINTRODUCTION
The Glossary of Orthodontic Terms defines
open bite as a developmental or acquired
malocclusion whereby no vertical overlap exists
between maxillary and mandibular anterior or
posterior teeth.
22

33
Description of open-bite differ among various
authors and investigators.
SOME AUTHORS CONSIDER-
1. Open-bite to be present when there is less than an
average overbite.
2. Open-bite to be present when there is edge-to edge
relationship.
3. Open-bite to be present when a definite degree of
openness is present.

55
 Open-bite must be considered as a deviation in the
vertical relationship of the maxillary and mandibular
dental arches.
 In an open-bite there should be a definite lack of
contact, in the vertical direction, between opposing
segments of teeth.
 The degree of openness can vary from patient to
patient, but an edge-to-edge relationship or some
degree of overbite cannot be rightfully categorized as
an open-bite.
 The loss of contact, in the vertical direction, of
segments of teeth can occur between the anteriorthe anterior
segmentssegments or between the buccal segmentsbuccal segments.

66
TYPES OF VERTICAL MALOCCLUSIONTYPES OF VERTICAL MALOCCLUSION
Problems in the vertical dimension includes open bite
and deep bite malocclusion and also facial
disfiguration.
Some problems can be divided into those that are
limited to the dentoalveolar area and those that
predominantly are of skeletal nature.

77
If only dentoalveolar structuresdentoalveolar structures are involved, the terms
open bite and deep bite are used.
If skeletal structuresskeletal structures are involved, the types of vertical
facial patterns can be described as hyperdivergent and
hypodivergent.
These vertical dysplasias clinically have been termed
long face syndrome and short face syndrome.
Generally, facial patterns with a mandibular plane angle
greater than 303000
are considered hyperdivergent, and
less than 202000
hypo divergent.

88
Skeletal open bite occurs as a result of
increased downward and backward
inclination of the mandible and hence the
mandibular angle is increased.
Open bite of dentoalveolar origin
occurs as a result of underdevelopment
of anterior part of the maxillary and
mandibular alveolar processes.
Differentiation Between Skeletal &Differentiation Between Skeletal &
Dentoalveolar MalocclusionDentoalveolar Malocclusion

99
Overview of Open BiteOverview of Open Bite
Non-Occlusion
1. Traditionally open bite implies “opposing teeth do not
meet”.
2. Vander Linden, however, has indicated that the
overlap criterion is arbitrary and is associated with the
sagital relation between the teeth involved.
3. The absence of an Occlusal stop between the teeth
with their antagonists or opposing gingiva is of greater
significance.
4. Absence of such a stop means that the eruption
process has been arrested by one or more factors.

1010
5. The same view was expressed by Moyers, who stated
that it is most important to use the term “open bite” for
all conditions characterized by the absence of an
Occlusal stop.
6. In the international literature, however, this
recommendation has not been implemented, and the
term ‘open bite” still is used only for conditions without
vertical overlap.

1111
7. Anterior non-occlusion Occurs in the incisor area and
usually is associated with some degree of overlap of
the incisors, as observed often in patients with Class II,
division 1 malocclusion.
8. Posterior non-occlusion can occur in the premolar or
molar region, with great variation occurring in the
number of teeth and the Occlusal surfaces involved.

1212
9. Total non-occlusion, here the tongue is positioned
between the opposing teeth most of the time.
10. Non-occlusions are more common than open bites.
That holds true for the anterior and posterior regions.
When asked to
close the teeth
together.
Habitual
positioning
of Tongue

1313
ESTHETIC CONSIDERATIONSESTHETIC CONSIDERATIONS
1. Balance between the nose, lips, and chin profile is
essential for optimal esthetics.
2. The nasolabial angle also is important.
3. The dentoalveolar open bite malocclusion is
esthetically unattractive particularly during speech
when the tongue is interposed between teeth and thetongue is interposed between teeth and the
lips.lips.

1414
FUNCTIONAL CONSIDERATIONFUNCTIONAL CONSIDERATION
1. Tongue posture and function should be primary
considerations in Open-bite problems.
• Acc. To Proffit “if a patient has a forward thrusting
postureposture of the tongue the duration of this pressure
even if very light could affect tooth position vertically or
horizontally”.

1515
2. Differentiation between primary causal and secondary
adaptive or compensatory tongue dysfunction is
essential.
• Acc. to Proffit “A tongue thrust swallow is a useful
physiologic adaptationphysiologic adaptation if you have an open bite, which
is why an individual with an open bite also has a tongue
thrust swallow” (i.e. Secondary adaptive tongue
dysfunction)

1616
According to Rakosi, four varieties ofAccording to Rakosi, four varieties of open biteopen bite
due to tongue posture may be differentiateddue to tongue posture may be differentiated::
Anterior Open BiteAnterior Open Bite
Open bite in a deciduous
dentition, caused by a tongue
dysfunction as a residium of a
sucking habit.
Habitual position
The tongue is positioned forward
during functioning, thus
impeding the vertical
development of the
dentoalveolar structures around
the upper and lower anterior
teeth.

1717
Lateral Openbite
Occlusion, In this type of open bite
the occlusion on both sides is
supported only anteriorly and by the
first permanent molars.
Habitual Position
The tongue thrusts between the
teeth laterally.
The tongue dysfunction occurs in
conjunction with a disturbance in
the physiologic growth processed
around the first and second
deciduous molars.

1818
Complex open bite:
Severe vertical
malocclusion. The teeth
occlude only on the second
molars.
Habitual Position
Tongue-thrusting occurs
during function.

1919
Tongue dysfunction and
malocclusion:
In mandibular prognathism,
the downward and forward
displacement of the tongue
often causes an anterior
tongue-thrust habit.

2020
Cephalometric CriteriaCephalometric Criteria
A proper cephalometric analysis enables a classification of
open bite malocclusions:
1. Dento Alveolar Open Bite.
2. Skeletal Open Bite.
1. Positional Deviations.
2. Dimensional Deviations
3. Skeletal Class II Open Bite
4. Skeletal Class III Open Bite

2121
Dento alveolar open bite
1. The extent of the dentoalveolar open bite depends on
the extent of the eruption of the teeth.
2. Supraocclusion of the molars and infraocclusion of the
incisors can be primary etiologic factors.

3. In vertical growth
patterns,the
dentoalveolar
symptoms include a
protrusion in the
upper anterior teeth
with-lingual
inclination of the
lower incisors.

4. In horizontal growth
patterns, tongue posture
and thrust may cause
proclination of both
upper and lower
incisors.

2424
Skeletal Open BiteSkeletal Open Bite
1. Dysgnathia with a vertical growth
pattern
2. The downward and backward
rotation of the mandible is the
cause of the anterior open bite.
The gonial angle and its lower
segment are markedly enlarged.
3. The clinical picture of the open bite
is partly compensated by the
linguo-version of the upper anterior
teeth.

2525
SKELETALSKELETAL CLASS IICLASS II OPEN BITEOPEN BITE
1. This combination is primarily an open-bite type,
positionally and dimensionally.
2. The major variant here is in the antero-posterior
dimensions of the jaws. The palate may be longer, and
the mandible shorter.
3. The differential evaluation of these two possibilities is
important, as the prognosis and the treatment approach
may be different.
4. In this respect, it points out that a given dental Class II
malocclusion may be present in opposite facial types.

2626
5. In this type, in some instances, the rotation of the
mandible may be purely positional. Often this is due to a
downward and backward rotation of the mandible.
6. This rotation is associated with excessive extrusion of
the molars. If these interferences were removed, the
mandible could be permitted to rotate in a closing
direction, improving the Class II and the open-bite
patterns simultaneously.

2727
SKELETALSKELETAL CLASS IIICLASS III OPEN BITEOPEN BITE
1. This combination consists primarily of an open-bite with
a palatal deficiency or a large mandible.
2. Among the facial deformities, these have probably the
worst prognosis in terms of dentofacial orthopedics.
3. If correction of this open-bite is attempted by rotating
the mandible in a closing direction, the protrusion of the
chin is increased.

2828
4. On the other hand,if the reduction of the mandibular
protrusion is attempted by rotating the mandible
downward and backward, the open-bite is increased.
5. Even surgical correction of the mandible is of limited
benefit here, as the teeth interfere in the closing of the
lower face height.

3030
Various Forms Of Anterior Open BiteVarious Forms Of Anterior Open Bite
1. An overjet combined with an open bite of less than 1mmless than 1mm
can be designated as pseudo-open bite problems.
2. A simple open bite exists in cases in which more than
1 mm of space may be observed between the incisors,
but the posterior teeth are in occlusion.
3. A complex open bite designates those cases in which
the open bite extends from the premolars or deciduous
molars on one side to the corresponding teeth on the
other side.

3131
4. The compound or infantile open bite is completely
open, including the molars.
5. The iatrogenic open bite is the consequence of
orthodontic therapy, which produces atypical
configurations because of appliance manipulation or
adaptive neuromuscular response.

3232
Vertical MalpositionVertical Malposition
 Vertical malpositioning of groups of teeth is judged in
relation to the occlusal plane.
 “Infraversion” or “infraocclusion” indicates that teeth
have not yet reached the level of the occlusal plane.
 This malpositioning usually occurs in conjunction with
irregularities in the vertical development of the alveolar
process.

3333
Infraocclusion Of The Anterior TeethInfraocclusion Of The Anterior Teeth
Open bite malocclusion; the upper incisors do not reach
the occlusal plane. The alveolar process is noticeably
undeveloped in the anterior region.

3434
1. An open bite associated with divergence of the skeletal
planes is termed as skeletal open bite or apertognathia.
2. characteristics of a skeletal open bite include
a) increased lower anterior facial height,
b) increased total anterior facial height,
c) increased gonial, mandibular plane and Occlusal
plane angles,
d) decreased palatal plane angle,
e) occasional maxillary retrognathia, and
f) increased vertical maxillary and mandibular
dentoalveolar dimensions.
Clinical assessment of skeletal open bite

3535
Four Major Factors In The DentalFour Major Factors In The Dental
EquilibriumEquilibrium
1. Intrinsic forces by tongue and lips.
2. Extrinsic forces: habits (thumb-sucking, etc), orthodontic
appliances.
3. Forces from dental occlusion.
4. Forces from the periodontal membrane.

3636
Intrinsic Forces By Tongue And LipsIntrinsic Forces By Tongue And Lips
1. The teeth are positioned between the lips and cheeks
on one side and the tongue on the other, the opposing
force or pressures from these organs should be major
determinants of the dental equilibrium.
2. A superficial consideration of the dental equilibrium
requires that a distinction be made between the amount
of force generated against a tooth and the duration of
force application.

3737
3. Wave of enthusiasm was triggered by Walter Straub in
the 1950’s after he had decided from clinical
observation that incorrect swallowing was a major
cause of anterior open bite and incisor protrusion.

3838
4. It seemed logical that patients who swallowed incorrectly
should have protruding incisors or open bite because
of different tongue and lip pressures.
5. Investigators quickly noted that tongue pressures
during swallowing always are several times higher than
the lip or cheek pressure which should balance them.
6. When time–pressure integrals are compared, tongue
and lips come closer to balance, but tongue pressure is
still considerably greater than lip pressure.
7. There is no balance of pressures for swallowing.

3939
EXTRINSIC FORCESEXTRINSIC FORCES
(External Pressure Habits and Orthodontic(External Pressure Habits and Orthodontic Appliances)Appliances)
1. All clinical orthodontics is based on moving teeth by
deliberately altering the force equilibrium on the
dentition.
2. Teeth can be moved effectively by a force of only a few
grams provided that the force is maintained
continuously.
3. The duration of force is a more critical variable in
orthodontic treatment than force magnitude.
4. The same is true for external pressure habits, such as
thumb sucking.

4040
Thumb SuckingThumb Sucking

4141
5. The greater the duration of the habit, the greater its
impact on the teeth is likely to be. For both orthodontic
appliances and habits, durations must be measured in
hours per day to produce significant changes in tooth
position.
6. Extrinsic forces can be quite effective when their
duration approaches fifty percent of the time, and some
impact apparently can be produced by durations of only
a few hours.

4242
FORCES FROM DENTAL OCCLUSIONFORCES FROM DENTAL OCCLUSION
1. The attachment apparatus of all teeth is an effective
hydrodynamic damping system, like an automobile
shock absorber and is well designed to withstand
occlusal forces.
2. The teeth would make minor corrections of themselves.
This does happen just after the completion of
orthodontic treatment, when the teeth are hyper mobile
and the attachment apparatus is reorganizing.
3. It is common experience that teeth remain in positions
of traumatic occlusion rather than moving away from the
offending occlusal contacts.

4343
4. If the molar teeth are extruded by orthodontic forces, the
mandible will rotate downward and backward as the
Occlusal contact and rest positions change. Once a
natural tooth has erupted or been extruded, the
musculature adapts to its position.
5. Mandibular positioning during growth influences eruption
and the final vertical position of the teeth remains
entirely unknown. Occlusal forces during growth
probably play a significant role.

4444
FORCES FROM THE PERIODONTALFORCES FROM THE PERIODONTAL
MEMBRANE:- ERUPTION FORCESMEMBRANE:- ERUPTION FORCES
1. An eruption force is generated which moves a tooth
through bone and continues to move it after it has
broken into the oral cavity. The eruptive force remains
active after a tooth has come into occlusion and
function has been established.
2. Eruption continues along with vertical growth of the face
e.g. a maxillary first molar typically erupts for a
centimeter or between age six when it first comes into
occlusion and the time in the late teens when vertical
jaw growth ends.

4545
INFLUENCE OF NASORESPIRATORY FUNCTIONINFLUENCE OF NASORESPIRATORY FUNCTION
1. Physiologic adaptations to various types of upper
respiratory obstruction (eg constricted external nares,
deviated septum, nasal polyps enlarged adenoids,
enlarged tonsils) initially may lead to altered functional
activity of the muscles associated with respiration.
2. It is hypothesized that this change in the level of
postural activity of certain craniofacial muscles
ultimately may lead to a change in craniofacial
morphology, particularly in the vertical dimension.

4646
4. Changes in the level of level of activity of certain
craniofacial muscles leads to an extension of the head
and airway maintenance.
5. This alteration causes a stretching of the masticatory
and facial muscles as well as the associated soft tissue.
6. A prolonged obstruction of the airway can lead to
skeletal remodeling and ultimately a change in
craniofacial morphology.
7. The possible relationship between airway obstruction
and aberrant craniofacial growth is the type of patients
described as having ‘adenoid facies.’

4747
8. These patients typically present a mouth- open posture,
a small nose with button like tip, nostrils that are small
and poorly developed, a short upper lip, prominent
maxillary incisors, a pouting lower lip, and a vacant
facial expression.
9. ‘Mouth-breathing” individuals classically have been
described as possessing a narrow, V-Shaped maxillary
arch, a high palatal vault, proclined maxillary incisors,
and a Class II occlusion.

4848
Examination of Orofacial DysfunctionsExamination of Orofacial Dysfunctions
Swallowing
Tongue
Speech
Lips
Respiration

4949
SwallowingSwallowing
Normal mature swallowing takes place without contracting the
muscles of facial expression. The teeth are momentarily in
contact and the tongue remains inside the mouth.
Abnormal swallowing is caused by tongue-thrust, either as
simple thrusting
action
Tongue-thrust syndrome

5050
The following symptoms distinguish Tongue Thrust
Syndrome:
1) Protrusion of the tip of the tongue .
2) No contact of the molars.
3) Contraction of the perioral muscles during the
deglutition cycle.
 During their first few years, infants swallow viscerally,
i.e. with the tongue between the teeth
 As the deciduous dentition is completed, the visceral
swallowing is gradually replaced by somatic swallowing.

5151
Visceral (Infantile) Swallow In The NeonateVisceral (Infantile) Swallow In The Neonate
The jaws are apart during swallowing. The tongue is
pushed forward and placed between the gum pads.
The tip of the tongue protrudes.
The mandible is stabilized by the contraction of the
tongue and the oro-facial musculature as well as by the
tongue contact with the lips.

5252
Somatic SwallowSomatic Swallow
As swallowing is triggered off by contraction of the
mandibular elevators (masseter muscle), the teeth
occlude momentarily during the swallowing act and the
tip of the tongue is enclosed in the oral cavity.
The transverse section shows that the dorsum of the
tongue is less concave and approaches the palate
during swallowing (according to Graber, 1972).

5454
Tongue-thrust has an important effect on the
etio pathogenesis of malocclusions
Tongue-Thrust
Primary
secondary
Anterior
Lateral
complex
Endogenous
Habitual
adaptive

5555
The thrust may take place in the anterior or lateral
regions or can be complex. In the first case, the
dysfunction is significant during the development of an
anterior open bite and in the latter, during the
development of a lateral open bite or a deep overbite.
In case of a complex tongue-thrust, the occlusion is
supported only in the molar region.
Cases with an anterior open bite during childhood are
often self-compensating. Complex or skeletal open
bites do not regulate themselves spontaneously, but
rather persist.

5656
Primary tongue dysfunction in
conjunction with hyperplastic
tonsils-
A retracted tongue would touch
infected, swollen tonsils if these
were to protrude far out of the
surrounding structures. In order to
avoid painful sensations and to
keep the oral airway open the
mandible is dropped and the
tongue postures forward
(according to Moyers).

5757
Adaptive tongue dysfunction
Adaptive tongue dysfunction with tooth malposition.
After loss of teeth, the tongue is used to fill the gaps, thus
sealing the oral cavity, i.e. compensatory dysfunction.
In cases with premature extraction of deciduous teeth, this
primarily physiologic displacement of the tongue may
persist as a functional abnormality even after the permanent
teeth have erupted.

5858
Enamel hypoplasia of the upper and lower anterior teethEnamel hypoplasia of the upper and lower anterior teeth
as well as of the first molars results from a vitamin Das well as of the first molars results from a vitamin D
deficiency which occurres at the age of about 1 year.deficiency which occurres at the age of about 1 year.
The skeletal and dentoalveolar open bite is aggravated byThe skeletal and dentoalveolar open bite is aggravated by
the adaptive tongue dysfunction.the adaptive tongue dysfunction.
Open Bite Due To RicketsOpen Bite Due To Rickets

5959
Mouth BreathingMouth Breathing
Chornically disturbed nasal respiration represents a
dysfunction of the orofacial musculature; it can restrict
development if the dentition and hinders the orthodontic
treatment.
The extraoral appearance of these patients is often
conspicuous. And is termed “adenoid facies”

6060
Adenoid Facies
Chronically restricted nasal
respiratory function.

6161
Occlusal and dental findings in case of oronasal
respiration
The upper jaw is markedly
constricted, the mandibular
arch is well formed With a
bilateral cross-bite
The high palate and narrow
upper arch

6262
Treatment In Primary Dentition
Treatment In Mixed Dentition
Treatment In Permanent Dentition
TREATMENT

6363
TREATMENT IN THE DECIDUOUS DENTITIONTREATMENT IN THE DECIDUOUS DENTITION
1. Control of abnormal habits and elimination of
dysfunction should be given top priority in the deciduous
dentition.
2. The anterior open bite improves as soon as the habit is
stopped.
3. Autonomous improvement can be expected only if the
deforming muscle activity is terminated and the open
bite is not complicated by crowding or cross bite of the
upper arch.

6464
4. Treatment with screening appliances is indicated in
such open- bite cases.
5. A skeletal open bite is seldom observed in the
deciduous dentition. Habit control is of only secondary
consideration in these cases, retarding the increasing
severity of the dysplasia.
6. Extra oral orthopedic appliances such as chin cups can
be used effectively to redirect growth.

6565
Screening ApplianceScreening Appliance
1. Screening appliances intercept and eliminate all
abnormal perioral muscle function in acquired
malocclusions resulting from abnormal habits like mouth
breathing, and nasal blockage.
2. Open bite created by finger sucking and retained
visceral deglutition-pattern, tongue function can be
helped with vestibular screens.

VESTIBULAR SCREENVESTIBULAR SCREEN
Screening appliance used
to correct mouth breathing
habit.
Extends vertically from
upper labial fold to lower
labial fold & horizontally
from the distal surface of
last erupted molars on one
side to other.
Worn at night & 2-3 hours
during daytime daily.

6767
Tongue CribTongue Crib
1. A removal or fixed appliance can inhibit tongue thrust.
2. The crib used with a removable appliance for an
anterior open bite consists of a palatal plate with a
horseshoe-shaped wire crib.
MIXED DENTITION- TREATMENT

6868
5. The acrylic also can be interposed between the teeth,
covering the occlusal surfaces of the upper molars, to
prevent eruption of these teeth and enhance anchorage
of the plate. This is especially beneficial in open-bite
problems.
6. In such cases a stretch reflex is elicited from the
closing muscles that enhances the depressing action
on the buccal segments and helps close the anterior
open bite.

ANTERIOR TONGUE THRUSTANTERIOR TONGUE THRUST

Bio mechanical considerations of Open bite. Dr. Ajay

7373
ActivatorActivator
1. The bite is opened 4 to 5 mm to develop a sufficient
elastic depressing force and load the molar that are in
premature contact.

7474
4. To “close the V” between upper and lower maxillary
bases, depressing the posterior maxillary segments with
the activator in a manner analogous to that of
orthognathic surgery
5. In surgical open-bite cases the posterior segments are
impacted, allowing autorotation of the mandible.

7575
BionatorBionator
1. Used to inhibit abnormal posture and function 0f the
tongue.
2. The construction bite is as low as possible, but a slight
opening allows the interposition of posterior acrylic bite
blocks for the posterior teeth, to prevent their extrusion.
3. To inhibit tongue movements, the acrylic portion of the
lower lingual part extends into the upper incisor region
as a lingual shield. Closing the anterior space without
touching the upper teeth.

7676
4. The palatal bar has the same configuration as the
standard bionator, with the goal of moving the tongue
into a more posterior or caudal position.
5. The labial bow differs from the standard appliance, that
the wire runs approximately between the incisal edges
of the upper and lower incisors.

7777
6. The labial part of the bow is placed at the height of
correct lip closure thus stimulating, the lips to achieve a
competent seal and relationship.

7878
FR IVFR IV
1. Normally, anterior open bite problems show protracted
tongue posture with incompetence of lips. The tongue
tooth contact replaces the lip seal during deglutition to
create negative atmospheric pressure.
2. FR IV along with lip exercises cause lip contact,
reducing tongue protrusion and cause the tongue to
move back into its normally raised position in proximity
with palate, during deglutition.

7979
3. The palatal bow is like that of the FR-3 and is always
placed behind the last molar to permit the appliance to
shift in a posterior direction.
4. This allows the mandible to close up and forward into a
more favorable growth direction reducing the
mandibular plane angle.

Headgears with posterior bite blocksHeadgears with posterior bite blocks
Openbite can be corrected
by molar intrusion.
Galletto in 1990, used
posterior bite blocks in
conjunction with vertical
pull headgear to reduce
lower facial height by
intruding molars & upward
& forward rotation of
mandible.

Headgear With Functional ApplianceHeadgear With Functional Appliance
Lucaine Closs in
1996 used headgear
with functional
appliance for
correcting skeletal
openbite.

8282
Vertical pullVertical pull
chin cupchin cup

8383
Bracket PositionBracket Position
1. The placement point for incisor brackets may vary in
cases of infraocclusion.
2. In cases of open bite, anterior brackets are placed I mm
more towards the gingival side.

8484
Modifications To StandardModifications To Standard
SequenceSequence
1. The only two changes from the standard sequence are
in bracket placement and the closing loop gable bend.
2. On those teeth in occlusion, the brackets are placed as
close to the occlusal surface as possible.
3. On all the teeth out of occlusion, the brackets are
placed more gingivally.
R.G. “Wick” Alexander

8585
Triangle ElasticsTriangle Elastics
1. Triangle elastics aid in the improvement of class I
cuspid intercuspation and increasing the overbite
relationship anteriorly by closing open bites in the range
of 0.5 to 1.5 mm.
2. They extend from the upper cuspid to the lower cuspid
and first bicuspid teeth.

8686
Anterior Vertical ElasticsAnterior Vertical Elastics
 Class II orientation.
 Class III orientation

8787
Avoid Intermaxillary ElasticsAvoid Intermaxillary Elastics
1. Intermaxillary elastics from the posterior teeth have a
vertical force vector which extrudes these teeth and can
further open the posterior vertical dimension.
2. Class II elastics from 6 - 6 should not be utilized until
these teeth are well anchored in buccal cortical bone .

8888
How To Use Class II Or Class IIIHow To Use Class II Or Class III
ElasticsElastics
1. If class II or III elastics are required, they should be
attached posteriorly to premolars rather than molars.
2. These ‘short elastics minimize the extrusive effect on
the back of the arch

8989
ACTIVE VERTICAL CORRECTORACTIVE VERTICAL CORRECTOR
1. AVC is a simple removable or fixed orthodontic
appliance that intrudes the posterior teeth of both the
maxilla and mandible by reciprocal forces.
2. By effective intrusion of posterior teeth, the mandible is
allowed to rotate in upward and forward directions.

9090
3. The uniqueness of this appliance is that, it corrects
anterior open bite problems by actually reducing
anterior facial height.

9191
Method of Action :-
1. Force system -- generated by repelling magnets,
2. AVC is considered superior to a static bite block
appliance energized only by the intermittent force from
the muscles of mastication.
The constant force system of the AVC results in greater
rapidity of tooth movement.

9292
ToothTooth PositionerPositioner
1. In open-bite cases, a tooth positioner may be used for 6
to 8 weeks of night-time wear
2. This appliance places elastic forces to the teeth and
brings them into a predetermined ideal position.

9393
3. It helps to keep the
open bite closed as
the teeth are pulled in
a vertical direction
Bonded fixed and
Hawley retainers are
also given to these
patients for long-term
retention.

9494
Low transpalatal archLow transpalatal arch
1. It is considered that the transpalatal bar interferes with
the normal vertical descent of the upper molars, and
therefore retards maxillary vertical alveolar
development.
2. It has also been stated that maxillary vertical alveolar
growth contributes to one third of the total vertical
development of the face

9595
3. It is believed that, tongue pressure against the
transpalatal arch during swallowing, especially when
the transpalatal arch is placed low in the palate, will
inhibit maxillary alveolar vertical growth.
4. Wise et al. assessed pre and post treatment
cephalometric radiographs in the study.
– They found that the transpalatal bar has no
statistically significant effect on the amount of
vertical eruption of the maxillary teeth.

9696
Low Mandibular Lip BumperLow Mandibular Lip Bumper
1. Cetlin and Hoeve advocated the use of a lip bumper for
the development of the lower dental arch.
2. They suggested that if the lip bumper were adjusted
low, the cheek and lip mucosa would rest above the
appliance, and this will inhibit vertical mandibular molar
dentoalveolar development.

9797
Wedge Principle Coupled With TheWedge Principle Coupled With The
Extraction Of TeethExtraction Of Teeth
Two major approaches of applying the wedge principle
by extraction of teeth to control the vertical dimensions.
1. Loss of posterior anchorage so that the anchor
teeth move mesially and are located farther
anteriorly in the arch in an area of greater vertical
dimension.
2. Extraction of first or second molars in both
arches to decrease the posterior dentoalveolar
height.

9898
Garlington and Logan found that enucleation of
mandibular second premolars is beneficial,
 To control the vertical dimension.
 Increase in forward rotation of the mandible.
 Significant decrease in lower anterior face height.
 Pearson stated that after the extraction of premolar
teeth, there is some mesial drift of the posterior teeth
(out of the wedge) and this permits the mandible to be
hinge closed.

9999
1. The extrusion arch is a term coined to describe the
reverse action of already existing and well established
intrusion arch.
2. Anterior open bite can be addressed with arch wire
mechanics using asymmetrical V bends in the wire.
3. Wire used is
 16 x 22 SS or 17 X25 TMA with 900
offset
bend at the molar.
 Extrusive force of 100 gms for 4 incisors is
applied.
EXTRUSION ARCH

100100
Mode Of ActionMode Of Action
AT THE MOLAR:-
1. A second order couple is generated at the molar with
crown tipping mesially and root tipping distally.
2. The equilibrium is achieved because the anterior end of
the wire extrudes the incisors and posterior end
intrudes the molars.
3. Relatively very minimal buccal flaring of the molar is
seen.

103103
AT THE INCISORS:-
1. Extrusion can involve single teeth or group of teeth.
2. When a group of teeth are to be extruded ,a segment of
heavy arch wire may be used in the brackets of the
anterior teeth, and the teeth are extruded as if they
were one big tooth.
3. Whether the extrusion arch is tied segmentally or to
continuous arch wire or placed directly into the
brackets the effect is the same

107107
Multiloop Edgewise Arch WireMultiloop Edgewise Arch Wire
1. Multiloop Edgewise Arch Wire was developed by Kim to
achieve these goals :-
a. Correcting the inclination of the occlusal planes.
b. Aligning the maxillary incisors relative to the lip
line.
c. Uprighting the axial inclinations of the posterior
teeth.

108108
1. The MEAW contains horizontal and vertical loops
fabricated from a 16 x 22 ss wire in an L - shape
fashion
2. The vertical loops act as a break between the teeth,
lowers the load deflection rate and provides horizontal
control.
3. The horizontal loops further reduces the load deflection
rate and provides vertical control.

110110
4. Typical tip back bends of 3-5degrees are given on each
tooth.
5. Elastics are placed between the loops that lie mesial to
opposing cuspids.
6. Recommended elastic size is 3/16 inch heavy, with a
force approximately 50 gms when the jaw is closed.

112112
 KIMS technique was later modified by AYHAN
ENACAR et.al, using 16 x 22 reverse curve NiTi arch
wires with heavy intermaxillary elastics applied in the
canine region

113113
Skeletal Anchorage SystemSkeletal Anchorage System
1. Skeletal anchorage system was developed for tooth
movements.
2. SAS consists of titanium miniplates, that are
temporarily implanted in the maxilla or the mandible as
an immobile anchorage.

114114
3. These miniplates are fixed at the buccal cortical bone
around the apical regions of the lower first and second
molars on both the sides.

115115
Care Regarding use of appropriateCare Regarding use of appropriate
force systemforce system
1. Light forces and preparation of anchorage may prevent
extrusion of the posterior teeth.
2. The segmented arch technique is considered to be
superior in preventing posterior dental extrusion during
incisor intrusion
3. It is preferable to include second molars in the posterior
segments to distribute the forces of occlusion over a
larger area, thereby counteracting the extrusive forces
on the buccal segments

116116
ConclusionConclusion
 Indeed it is a daunting and challenging job to treat open
bite cases.
 The treatment of open bite remains a challenge to the
clinician, and careful diagnosis and timely intervention
will improve the success of treating this malocclusion.
 The difficulties encountered in obtaining stable results for
AOB correction can be justified by the fact that their true
etiology still defies understanding.

REFERENCESREFERENCES
1. Subtelny, J. D.: Open-bite: Diagnosis and treatment,
Am.J.orthod. 42; 337, 1964.
2. Hellman, M.: Open bite, Am J. orthodont. 17: 421,
1931.
3. Robert J Issacson, Closing anterior open bite :the
extrusion arch. Seminars in orthodontics. 7.34 – 41 .
2001
4. Vertical Control with a Headgear- Activator
CombinationCLAUDE CHABRE, DCD, DSO
JCO 1990 OCT 618 - 624

5. Parker JH. The interception of the open bite in the early
growth period. Angle Orthod. 1971 Jan;41(1):24-44.
6. Alderico Artese et al. Criteria for diagnosing & treating
anterior open bite with stability. Dental Press J Orthod. 2011
May-June;16(3):136-6
7. Nawal Khan. Openbite Review. International Journal of Health
Sciences & Research. 288 Vol.4; Issue: 9; September 2014
8. Wiley Blackwell. Openbite malocclusion Treatment &
Stability.
9. Ravindra Nanda. Biomechanics & Esthetic Stratergies in
Clinical Orthodontics.

Bio mechanical considerations of Open bite. Dr. Ajay

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