BIO - MECHANICAL
CONSIDERATION IN OPEN BITE
INDIAN DENTAL ACADEMY
Leader in continuing dental education
Types Of Vertical Malocclusion.
Overview Of Open Bite.
Examination of Oro-Facial Dysfunction
Influence Of Naso-respiratory Function
Long Face Syndrome
The Association Between Anterior Open–Bite
and Amelogenesis Imperfecta
Treatment In Primary Dentition
Treatment In Mixed Dentition
Various Functional Appliances For Treatment
Of Open Bite
Treatment In Permanent Dentition
1. What is an open bite?
2. The diagnostic criteria of open bite require
What are we talking about as we loosely use the
descriptive term open bite?
Is it just a variation on another theme-a variable of the
Is it a separate clinical entity in which the openness
between the upper and lower teeth is the only factor
Etiologic factors related to open-bite must precede any
discussion of clinical treatment
Successful orthodontic therapy usually requires a
careful appraisal of etiological factors.
Unfortunately, it is not always possible to remove
factors that have caused or contributed to existing
Unfavorable growth or genetic determinants of a
malocclusion, including open-bite cannot be altered or
Description of open-bite differ among various
authors and investigators.
Open-bite to be present when there is less than an
Open-bite to be present when there is edge-to edge
Open-bite to be present when there is definite degree
of openness must be present.
Open-bite must be considered as a deviation in the
vertical relationship of the maxillary and mandibular
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
The loss of contact, in the vertical direction, of
segments of teeth can occur between the anterior
segments or between the buccal segments.
TYPES OF VERTICAL
TYPES OF VERTICAL MALOCCLUSION
Problems in the vertical dimension includes open bite
and deep bite malocclusion and also facial
Some problems can be divided into those that are
limited to the dentoalveolar area and those that
predominantly are of skeletal nature.
Open / Deep Bite
Hypo / Hyper divergent
(Short / Long face syndrome)
If only dentoalveolar structures are involved, the terms
open bite and deep bite are used.
If skeletal structures are involved, the types of vertical
facial patterns can be described as hyperdivergent and
These vertical dysplasias clinically have been termed
long face syndrome and short face syndrome.
Generally, facial patterns with a mandibular plane angle
greater than 300 are considered hyperdivergent, and
less than 200 hypo divergent.
Differentiation Between Skeletal &
Skeletal open bite as a result of
increased downward and backward
inclination of the mandible. The
mandibular angle is increased.
Open bite of dentoalveolar origin as a
result of underdevelopment anteriorly of
the maxillary and mandibular alveolar
OVERVIEW OF OPEN BITE
Overview of Open Bite
1. Traditionally open bite = “opposing teeth do not meet”.
2. Vander Linden, however, has indicated that the
overlap criterion is arbitrary and is associated with the
sagittal relation between the teeth involved.
The absence of an Occlusal stop between the teeth
with their antagonists or opposing gingiva is of greater
Absence of such a stop means that the eruption
process has been arrested by one or more factors.
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
In the international literature, however, this
recommendation has not been implemented, and the
term ‘open bite” still is used only for conditions without
7. The recently published Glossary of orthodontic Terms
defines non-occlusion as any situation in which the
teeth do not have maximum contact with their
antagonists in habitual occlusion.
8. 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.
9. 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.
10. Total non-occlusion, the tongue is positioned between
the opposing teeth most of the time.
11. Non-occlusions are more common than open bites.
That holds true for the anterior and posterior regions.
When asked to
close the teeth
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 the
4. The lower facial third is elongated in patients with
skeletal open bite.
1. Tongue posture and function should be primary
considerations in Open-bite problems.
Acc. To Proffit “if a patient has a forward thrusting
posture of the tongue the duration of this pressure
even if very light could affect tooth position vertically or
2. Differentiation between primary causal and secondary
adaptive or compensatory tongue dysfunction is
Acc. to Proffit “A tongue thrust swallow is a useful
physiologic 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
According to Bahr and Holt, four varieties
of tongue thrust may be differentiated:
1. Tongue thrust without deformation:-
abnormal function, no deformations ensues.
2. Tongue thrust causing anterior deformation:- i.e
anterior open bite, sometimes coupled with bilateral
narrowing of the arch and a posterior crossbite.
Moyers (1964) terms this a simple open bite.
3. Tongue thrust causing buccal segment deformation:-
with a posterior open bite is often seen clinically.
Lateral tongue thrust activity also can be responsible
for a functional deep bite, a variation of the posterior
open bite. Some Class II, division 2 malocclusion fit
this category. Invagination of the cheek into the
interocclusal space also may be a factor in this
Combined tongue thrust:- causing both an anterior
and a posterior open bite, is another common
dysfunction. This is called a complex open bite by
Moyers and is more difficult to treat.
According to Rakosi, four varieties of open bite
due to tongue posture may be differentiated:
Anterior Open Bite
Open bite in a deciduous
dentition, caused by a tongue
dysfunction as a residuum of
a sucking habit.
The tongue positioned forward
during functioning, thus
impeding the vertical
development of the
dentoalveolar structures around
the upper and lower anterior
Occlusion, In this type of open bite
the occlusion on both sides is
supported only anteriorly and by the
first permanent molars.
The tongue thrusts between the
The tongue dysfunction occurs in
conjunction with a disturbance in
the physiologic growth processed
around the first and second
Complex open bite:
malocclusion. The teeth
occlude only on the second
Tongue dysfunction and
In mandibular prognathism,
the downward forward
displacement of the tongue
often causes an anterior
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
Skeletal Class II Open Bite
Skeletal Class III Open Bite
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
5. A lateral open bite may be considered dentoalveolar in
combination with infra-occlusion of molar teeth.
Vertical growth pattern associated with anterior tongue
In Vertical growth pattern, tongue
thrust tends to tip the upper incisors
to the labial and the lower incisors
to the lingual.
• protrusion in the upper anterior
teeth with lingual inclination of
the lower incisors.
over eruption of posterior teeth
and steeper than normal
Horizontal growth pattern associated with anterior tongue
Horizontal growth pattern,
tongue thrust causes
bimaxillary dental protrusion,
i.e. labial tipping of upper and
lower anterior teeth.
The incisor relationships in a
case with an anterior open
horizontal growth pattern
Skeletal Open Bite
1. Dysgnathia with a vertical growth
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.
The clinical picture of the open bite
is partly compensated by the
linguo-version of the upper anterior
Acc to Sassouni…
1. The four bony planes of the face are steep to each
other, bringing the center 0 close to the profile.
2. The anterior arc, therefore follows the convexity of the
3. The posterior vertical chain of muscles is arcuate, and
the masseter muscle is posterior to the buccal teeth,
thus creating a mesial component of forces
responsible for the dental protrusion.
4. The cranial base angle and the gonial angle are obtuse.
5. The long axis of the incisors forms a small interincisal
Although the incisors are usually more extruded in the
open-bite type, this extrusion is not sufficient to
establish their vertical contact.
1. The total posterior facial height (S-Go) tends to be half
the size of the anterior total facial height (N-Me).
The lower anterior facial height exceeds the upper
anterior facial height.
The facial breadths tend to be narrow, giving a long,
ovoid appearance in the frontal view.
The nasal apertures are narrow.
The ramus is short with an antegonial notch at its lower
6. The mandible seems to have retained its infantile
characteristics, with all its processes underdeveloped.
7. The temporal fossa is small, suggestive of weak
8. The mandibular symphysis is narrow antero posteriorly
and long vertically.
9. There is a lack of chin mental protuberance
10.The cranium is sometimes dolichocephalic.
11. According to the Sheldonian somatotyping, the open12.
bite type rates high in ecto-morphs.
Proportionally large teeth characterize the dentition.
Crowding and bi-dental protrusion are often present.
Impaction or ectopic eruption of third molars is
The palatal vault is high and narrow.
16. The mouth is wide. The broad lips, short vertically
relative to their skeletal support, are kept apart at rest,
leading to mouth breathing.
When the lips are forcibly closed, the mentalis muscle
is displaced upward. This further increases the
“chinless” appearance of these persons.
SKELETAL CLASS II OPEN BITE
1. This combination is primarily an open-bite type,
positionally and dimensionally.
The major variant here is in the antero-posterior
dimensions of the jaws. The palate may be longer, and
the mandible shorter.
The differential evaluation of these two possibilities is
important, as the prognosis and the treatment approach
may be different.
In this respect, it points out that a given dental Class II
malocclusion may be present in opposite facial types.
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.
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
SKELETAL CLASS III OPEN BITE
1. This combination consists primarily of an open-bite with
a palatal deficiency or a large mandible.
Among the facial deformities, these have probably the
worst prognosis in terms of dentofacial orthopedics.
If correction of this open-bite is attempted by rotating
the mandible in a closing direction, the protrusion of the
chin is increased.
4. On the other hand, the reduction of the mandibular
protrusion is attempted by rotating the mandible
downward and backward, the open-bite is increased.
Even surgical correction of the mandible is of limited
benefit here, as the teeth interfere in the closing of the
lower face height.
SKELETAL OPEN BITE
SKELETAL FACTORS IN THE DEVELOPMENT
OF AN OPEN BITE TYPE:
1. The posterior half of the palate is tipped downward,
carrying the molars further downward. This gives rise to
a large palatomandibular plane angle.
The combination of an excessive development of the
upper mid-face heights (cranial base to molars) and a
lack of development of posterior facial heights (S-Go)
results in the downward and backward rotation of the
3. Because of the short ramus and the lower palate, the
pharyngeal space is constricted. In order to breathe,
these persons keep their tongues forward. Further
enhanced by the dental open-bite, there is a tonguethrusting tendencies.
When enlarged tonsils are present, the tongue is further
confined anteriorly. As the narrow palatal vault reduces
the necessary space, there is a tendency toward
tongue protrusion. This, in turn, may be a factor in the
creation of bi-dental protrusion.
Various Forms Of Anterior Open Bite
1. An overjet combined with an open bite of less than 1mm
can be designated as pseudo-open bite problems.
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.
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
4. The compound or infantile open bite is completely
open, including the molars.
The iatrogenic open bite is the consequence of
configurations because of appliance manipulation or
adaptive neuromuscular response.
Clinical assessment of dental open bite
1. 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.
the latter are caused by tongue interposition or by
disturbances in eruption (e.g ankylosis).
Posterior open bites rarely are due to primary failure of
eruption. Defects in eruption often are associated with
various craniofacial syndromes, including cleidocranial
dysplasia and Carpenter’s syndrome.
4. An open bite without facial disfiguration is classified as
a dental open bite and frequently is classified as dental
open bite and frequently is associated with a digital
sucking habit and / or tongue interposition.
The characteristics of a dental open bite include
problems typically restricted to the anterior teeth and
immediately associated hard and soft tissue structures
without remarkable cephalometric findings.
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
Correct vertical relation of the anterior and posterior
teeth to the occlusal plane (the imaginary plane passes
through the tips of the premolar cusps and is
perpendicular to the tuberosity plane).
Infraversion of the upper anterior teeth in conjunction with an
underdeveloped anterior alveolar process (Korkhaus, 1939).
Infraocclusion 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.
Clinical assessment of skeletal open bite
1. An open bite associated with divergence of the skeletal
planes is term as skeletal open bite or apertognathia.
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
d) decreased palatal plane angle,
e) occasional maxillary retrognathia, and
f) increased vertical maxillary and mandibular
3. Extreme skeletal open bite often are associated with
craniofacial malformations, such as the Crouzon’s
syndrome patient, in whom there are gross imbalances
in skeletal structures in all three dimensions of the face.
4. These types of problems are addressed only with
craniofacial surgery, including distraction osteogenesis.
5. Proffit and colleagues note that, although increased
lower anterior facial height exacerbates the problem by
adding a skeletal element, about one-third of patients
seeking surgical correction of long-face syndrome have
a normal or excessive overbite, rather than an open
bite, this type of occlusion is an indication of the
compensatory dental eruption that can occur in these
This illustrates that the long face syndrome and the
dental open bite are different entities.
Indeed, the facial disfiguration seen in skeletal open
bites can be found without the presence of dental open
bites; however, most instances, skeletal open bite is
combined with dental open bite.
The morphology of the facial skeleton and
the effects of tongue-thrusting are correlated
to a certain degree. In a vertical growth
pattern with tongue-thrust the lower incisors
are often in lingual inclination.
From the differential diagnostic point of
view, it is important to clarify both the
skeletal relationships and the tongue
dysfunction in order to localize the results of
the abnormal tongue functioning.
Equilibrium exists when a body at rest is subjected to
forces in various directions, but is not accelerated.
Malocclusion of the teeth and the broader spectrum of
dentofacial deformity is due, to an interplay between
innate genetic factors and external environmental
The environment of the teeth and alveolar bone includes
conflicting forces and pressures, primarily from
muscular function, which in part determine tooth
The more important these forces on the teeth are
conceived to be, the more one takes an
environmentalist view as far as the cause of
malocclusion is concerned.
The more one believes in inherited causes for
malocclusion, the less attention he is likely to pay to
the environment of the dentition.
During mastication’s not only do the teeth move slightly
but the alveolar bone and the basal bone of maxilla
and mandible bend and flex. These changes occur in
a matter of seconds, and the teeth and jaws are
restored to their original positions as quickly as they
Natural dentitions are stable over a time span of years
after growth is completed.
Angle felt that relapse after orthodontic treatment was
due to forces on the teeth resulting from an improper
environment. It is difficult even today to disagree with
The French molecular biologist “Jacob” quotes an
“however, there is always a desire in science to ‘explain
the complicated visible by some simple invisible”.
Tongue pressure, lip pressure, pressure from erupting
third molars all make nice “simple visible” causes for
Four Major Factors In The Dental
1. Intrinsic forces by tongue and lips.
2. Extrinsic forces: habits (thumb-sucking, etc), orthodontic
Forces from dental occlusion.
Forces from the periodontal membrane.
Intrinsic 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
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.
4. Tongue and lip pressures during swallowing never
5. It seemed logical that patients who swallowed
incorrectly should have protruding incisors or open bite
because of different tongue and lip pressures.
Investigators quickly noted that tongue pressures
during swallowing always are several times higher than
the lip or cheek pressure which should balance them.
When time–pressure integrals are compared, tongue
and lips come closer to balance, but tongue pressure is
still considerably greater than lip pressure.
There is no balance of pressures for swallowing.
8. The dental apparatus is well-adapted to resist shortacting forces such as those generated during chewing,
speaking and swallowing, where the duration of force
application is typically one second or less.
9. Only resting pressures of tongue and lips should be
considered as factors in the equilibrium.
10.This was and is a most reasonable suggestion, yet
resting pressures do not balance.
(External Pressure Habits and Orthodontic Appliances)
1. All clinical orthodontics is based on moving teeth by
deliberately altering the force equilibrium on the
Teeth can be moved effectively by a force of only a few
grams provided that the force is maintained
The duration of force is a more critical variable in
orthodontic treatment than force magnitude.
The same is true for external pressure habits, such as
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
6. Extrinsic forces can be quit effective when their
duration approaches fifty percent of the time, and some
impact apparently can be produced by durations of only
a few hours.
7. The discussion has related largely to tooth position in
the anterior, posterior and transverse planes of space.
What about the vertical plane of space, vertical tooth
position certainly can be influenced by environmental
8. Wallen indicate that vertically directed pressures during
swallowing actually are less in patients with anterior
open bite than in patients with normal vertical
9. The tongue pressures were greater in the open bite
patients than in the normal occlusion patients, it would
be easy to understand how the tongue was preventing
10.If the pressures were the same in open bite or normal
occlusion, one could say that the teeth were being
impeded by this pressure and held at a higher level.
11.It appears that the relatively high position of the incisors
keeps the tongue from contacting them quite so much
during swallowing. This does not support the idea that
tongue placement during swallowing causes open bite.
Certainly forward tongue position during swallowing,
which usually is called tongue thrust, is associated with
open bite but it seems more likely to be effect than
12.Jaw posture, occlusal force, and eruption force from the
periodontal membrane must be considered.
13.Other factors which come to mind immediately are
forces of occlusion and forces of eruption.
FORCES 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
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.
It is common experience that teeth remain in positions
of traumatic occlusion rather than moving away from the
offending occlusal contacts.
4. The mechanism to dissipate short- duration Occlusal
forces so that teeth do not permanently intrude or move
buccally or lingually because of occlusal forces,
occlusal forces can be important in equilibrium related
to vertical tooth position.
The vertical position of the teeth is determined by a
balance between the forces which oppose eruption and
those which promote it. Occlusal forces have an
influence related to this.
Numerous studies of occlusal forces it is known that a
maximum force of one hundred kilograms or more
sustained for only a fraction of a second can be exerted
against a single tooth during occlusion.
7. 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.
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.
FORCES FROM THE PERIODONTAL
MEMBRANE:- 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.
3. If its antagonist is extracted, any tooth may erupt again
years after its vertical position apparently was stable,
indicating that the eruptive mechanism remains intact
and capable of generating forces which can move a
Tooth eruption theories can be divided into
three major groups:
1. Theories based on cell proliferation at the root apex
2. Theories based on blood pressure- blood flow
differentials in the periodontal membrane
Theories based on metabolic change sin the periodontal
membrane, usually involving collagen polymerization.
The weight of present evidence indicates that eruptive
forces are generated in the periodontal membrane
rather than at the root apex, but exactly how remains
Tongue and lip pressures to produce a very sensitive
and highly stable transducer, which can be placed
against the tip of an erupting incisor.
INFLUENCE OF NASORESPIRATORY FUNCTION
1. Cause of vertical dysplasia is deviating neuromuscular
function associated with an abnormal breathing pattern.
Physiologic adaptations to various types of upper
respiratory obstruction (eg constricted external nares,
deviation septum, nasal polyps enlarged adenoids,
enlarged tonsils) initially may lead to altered functional
activity of the muscles associated with respiration.
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.
4. Changes in the level of level of activity of certain
craniofacial muscles leads to an extension of the head
and airway maintenance.
This alteration causes a stretching of the masticatory
and facial muscles as well as the associated soft tissue.
A prolonged obstruction of the airway can lead to
skeletal remodeling and ultimately a change in
The possible relationship between airway obstruction
and aberrant craniofacial growth is the type of patients
descried as having ‘adenoid facies.’
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 putting lower lip, and a vacant
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.
10.Patients who have severe allergies often presents with
similar facial manifestations. In addition, they may have
what are termed allergic shiners’ which represent a
pooling of blood under the eyes, a sign of the allergic
Examination of Orofacial
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
The following symptoms distinguish Tongue Thrust
1) Protrusion of the tip of the tongue .
2) No contact of the molars.
3) Contraction of the perioral muscles during the
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.
Tongue peristalsis during somatic swallowing:
I Collecting stage
II Transporting stage - Ist part of movement
2nd part of movement
3rd part of movement
III Third swallowing stage
IV Fourth swallowing stage
V Final stage
Collecting Stage –
The food is collected in the foremost part of the mouth, in front
of the retracted tongue. The posterior arched part of the dorsum
is in contact with the soft palate.
The lips are not in contact and the teeth are not occluding
Transporting stage Ist part of movement:
During the second phase of swallowing, i.e. the transporting
stage, the tip of the tongue first moves upward and the
anterior section of the dorsum is depressed (according to
Transporting stage 2nd part of movement:
The entire anterior section of the tongue then moves
upward and the central section of the dorsum is
This peristalsis transports the bolus rearward.
Transporting stage 3rd part of movement:
At the end of the transporting stage, the soft palate is
displaced upward and rearward.
The lip musculature contracts simultaneously, the lips are
together, the mandible is raised and the teeth come into
Third Swallowing Stage:
The dorsum of the tongue is depressed even further during
the third stage so that the bolus can pass through the
oropharyngeal isthmus; simultaneously the anterior part of
the tongue is pressed against the hard palate, thus forcing
more food rearward.
Passavant’s pad and soft palate form the palatopharygeal
seal and close the nasopharynx. The teeth are in full
occlusion and the lips in contact.
Fourth Swallowing Stage:
During the fourth sage of the swallowing act, the dorsum of
the tongue is moved further upward and rearward against
the soft palate and squeezes the remaining food bolus out
of the oropharyngeal area.
Final Stage Of Swallowing Cycle:
Once the swallowing act has been completed, the
mandible returns to its rest position.
Visceral (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.
Swallowing is triggered off and, to a large
extent, carried out by sensory interchange
between the lips and the tongue. Peristalsis
already commences in the vestibule.
The transverse section shows that the tongue
is positioned low in the mouth and that the
central furrow is depressed (according to
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).
Tongue-thrust has an important effect on the
etio pathogenesis of malocclusions
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 second case 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
Primary – Secondary Dysfunctions
Etiologic point of view, tongue-thrust
considered primary or secondary.
Principally speaking, all dysfunctions can be divided
into primary, i.e. causal or secondary, i.e. adaptive
Causes of dysfunction
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).
Moderately swollen palatine
tonsils which protrude
significantly from the tonsillar
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.
Open Bite Due To Rickets
Enamel hypoplasia of the upper and lower anterior teeth
as well as of the first molars results from a vitamin D
deficiency which occurred at the age of about 1 year.
The skeletal and dentoalveolar open bite is aggravated by
the adaptive tongue dysfunction.
Chornically disturbed nasal respiration represents a
dysfunction of the orofacial musculature; it can restrict
development if the dentition and hinders the orthodontic
The extraoral appearance of these patients is often
conspicuous. And is termed “adenoid facies”
Occlusal and dental findings in case of oronasal
The upper jaw is markedly
constricted, the mandibular
arch is well formed. Width a
The high palate and narrow
The Association Between Anterior Openbite And Amelogenesis
1. Amelogenesis imperfecta were investigated clinically,
and with cephalometric radiography in order to
determine the prevalence and nature of the anterior
It is suggested that the frequent association of anterior
open-bite and amelogenesis imperfecta is caused by a
genetically determined anomaly of craniofacial
development, rather than by local factors influencing
anomaly characterized by
infraocclusion or anterior open-bite.
5. “He and Issel believe that the co-existence of the two
conditions may be attributed to a pleiotropic action of
the amelogenesis imperfecta genes, influencing the
growth of the craniofacial skeleton.
7. Witkop and his co-workers, postulated that rough and
sensitive teeth lead to abnormal tongue activity which,
displaces the anterior teeth to produce a open-bite,
8. Locally interfere with the growth of the alveolar
processes, and could alter the morphology of the
BIO - MECHANICAL
CONSIDERATION IN OPEN BITE
Pr es ent ed b
Dr .Raj as heka
Types Of Vertical Malocclusion.
Overview Of Open Bite.
Examination of Oro-Facial Dysfunction
Influence Of Naso-respiratory Function
Long Face Syndrome
Treatment In Primary Dentition
Treatment In Mixed Dentition
Treatment In Permanent Dentition
TREATMENT IN THE
TREATMENT IN THE DECIDUOUS DENTITION
1. Control of abnormal habits and elimination of
dysfunction should be given top priority in the deciduous
The anterior open bite improves as soon as the habit is
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
4. Treatment with screening appliances is indicated in
such open- bite cases.
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 caps can
be used effectively to redirect growth.
1. Screening appliances intercept and eliminate all
abnormal perioral muscle function in acquired
malocclusions resulting from abnormal habits, 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.
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.
3. The crib is placed in the
area of local tongue
dysfunction and resultant malocclusion.
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
6. The bite-blocking here can be 3 to 4 mm, which is
usually beyond the postural vertical dimension in openbite patients.
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
1. The bite is opened 4 to 5 mm to develop a sufficient
elastic depressing force and load the molar that are in
2. Properly constructed activators that follow this principle
can influence the vertical growth pattern in these
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
5. In surgical open-bite cases the posterior segments are
impacted, allowing autorotation of the mandible.
1. Used to inhibit abnormal posture and function 0f the
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.
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.
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.
7. The vertical strain on the lips tends to encourage the
extrusive movement of the incisors, after eliminating the
adverse tongue pressures.
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.
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
mandibular plane angle.
Lloyd E Pearson
DESCRIBES SEVEN DIFFERENT PROCEDURES
FOR TREATMENT OF OPEN BITEWITH BACKWARD
Procedure -- I
1. In the mixed dentition open-bite patient we could intrude
the upper first permanent molars and then remove the
remaining deciduous teeth, permitting open-bite
2. occipital headgear with a transpalatal arch to control the
inclination of the molars as they are intruded.
3. After the molars have been intruded perhaps 3 mm the
deciduous teeth are removed, the mandible is hinged
closed, and the anterior open-bite is closed.
4. The lower molars will often tend to extrude in this type
of situation. Unless mechanics are designed to control
5. An addition of a vertical pull-chin cup to the occipital
headgear and transpalatal arch would intrude the upper
molars, while preventing the eruption of the lower
6. As the open bite closes the mandible hinges upward,
reducing the height of the lower face.
Vertical pull chin cup
Procedure -- II
1. Extraction of first premolars and use a vertical pull-chin
cup with (16 ounces of forces)
2. This can close the mandibular plane angle, reduce the
lower facial height and close anterior open bites.
3. Approximately 40 of closure of the mandibular plane
angle was found in his study.
4. Four possible mechanisms of (action at work)
a) maxillary sutures are pressure sensitive and some
intrusion of the maxilla could occur.
b) The posterior teeth tend to move forward mesially.
c) A slight change in the shape of the condylar neck,
with many tending to be curved more forward than
d) A retardation of eruption of the posterior teeth.
Procedure -- III
1. Mandibular bite- block therapy, augmented with vertical
pull-chin cup therapy, can produce a favorable holding
of the vertical height throughout the growth period,
intrusion of posterior teeth
hinging of the mandibular plane in a
counterclockwise direction and closure of anterior open
Procedure -- IV
1. Magnetic bite blocks.
2. Although we get rapid results, two difficulties arise with
a. Extreme mouth opening and patience to
tolerate the appliance.
b. lateral movement of the mandible, that can
cause some temporomandibualr joint strain.
Procedure -- V
1. Intrusive forces with fully banded appliances can be
developed in a number of ways.
Occipital headgear has proved useful and generally
seems effective in controlling the vertical dimension in
3. Mandibular control appears to be more difficult to
3. The lower molar normally increases its height as
measured to the mandibular plane by about 1.5 mm
over a two- year period
4. To reduce extrusion of the mandibular arch include a
lower cervical headgear with a very light force through
the center of resistance
Procedure -- VI
1. Another useful treatment modality is vertical reduction
2. One advantage, is that it does not involve the
3. It can be done after non-surgical treatment as an
adjunct to bring the chin up and forward, to improve
facial balance, and to achieve competency
4. A vertical reduction genioplasty might be more useful in
patients with the correct amount of exposed gingiva in
the maxilla because it does not provide maxillary
Procedure -- VII
1. Maxillary impaction + vertical reduction genioplasty,
should also be considered.
This can be a great benefit to patients with
elongated upper posterior teeth,
ii. elongated upper anterior teeth,
iii. a gummy simile,
iv. a tall lower face,
v. anterior maxilla with a maxillary impaction.
1. The placement point for incisor brackets may vary in
cases of infraocclusion.
2. In cases of open bite, placing anterior brackets I mm
more towards the gingival side.
Inverse Anchorage Technique
Modifications To Standard
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
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.
Anterior Vertical Elastics
Class II orientation.
Class III orientation
Avoid 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 .
How To Use Class II Or Class III
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
ACTIVE 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.
3. The uniqueness of this appliance is that, it corrects
anterior open bite problems by actually reducing
anterior facial height.
Problems formerly thought to require orthognathic
surgery, can now be treated successfully with AVC.
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.
3. The constant force system of the AVC results in greater
rapidity of tooth movement.
1. In open-bite cases, a tooth positioner may be used for 6
to 8 weeks of night-time wear
2. This appliances places elastic forces to the teeth and
brings them into a predetermined ideal position.
3. It helps to keeps 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.
Make sure, that the mandibular anterior teeth do not
contact the acrylic of the maxillary, because this would
open the bite in the posterior and promote tooth
extrusion, which would open the bite further
Low transpalatal arch
1. It is considered that the transpalatal bar interferes with
the normal vertical descent of the upper molars, and
2. It has also been stated that maxillary vertical alveolar
growth contributes one third of the total vertical
development of the face
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.
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.
5. However several authors suggested that future studies
with an integrated acrylic button on a lowered
transpalatal arch should be conducted.
Low 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
3. But there is no further explanation or evidence that a
lower lip bumper can be used to prevent eruption of the
mandibular molar teeth.
4. Similarly, a lower lingual arch may be used for
controlling vertical molar development; but there is lack
Wedge Principle Coupled With The
Extraction 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
2. Extraction of first or second molars in both
arches to decrease the posterior dentoalveolar
Garlington and Logan found that enucleation of
mandibular second premolars is beneficial,
To control the vertical dimension.
Increased in forward rotation of the mandible.
Significant decrease in lower anterior face height.
The criteria selection :a.
Minimal lower arch discrepancy (6 to 10mm).
A mandibular plane angle greater than 380.
A hyperdivergent skeletal pattern.
Increased lower anterior facial 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
Yamaguchi and Nanda concluded that the changes in
horizontal and vertical position of the molars were
dependent on the type of force application and not on
the extraction or non-extraction strategy.
The Extrusion Arch
1. The extrusion arch is a term coined to describe the
reverse action of already existing and well established
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.
Mode 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
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
wire or placed directly into the
brackets the effect is the same
High Pull Headgear
Multiloop 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
c. Uprighting the axial inclinations of the posterior
MEAW contains horizontal and vertical loops
fabricated from a 16 x 22 ss wire in an L - shape
2. The vertical loops act as a break between the teeth,
lowers the load deflection rate and provides horizontal
3. The horizontal loops further reduces the load deflection
rate and provides vertical control.
4. Typical tip back bends of 3-5degrees are given on each
5. Elastics are placed between the loops that lie mesial to
6. Recommended elastic size is 3/16 inch heavy, with a
force approximately 50 gms when the jaw is closed.
High Angle Begg Cases
1. In high angle begg cases we avoid class II elastics to
avoid open bite and accentuation of present class II .
2. We give mild class I elastics in such cases.
Skeletal Anchorage System
1. Skeletal anchorage system was developed for tooth
SAS consists of
titanium miniplates, that are
temporarily implanted in the maxilla or the mandible as
an immobile anchorage.
These miniplates are fixed at the buccal cortical bone
around the apical regions of the lower first and second
molars on both the sides.
4. Elastic threads are used as a source of orthodontic
force to reduce excessive molar height.
5. The lower molars were intruded about 3 to 5 mm, and
open-bite was significantly improved with little if any
extrusion of the lower incisors, with counter clockwise
rotation of the occlusal plane .
SAS is an effective adjunctive biomechanical
procedure for correction of skeletal open-bite
malocclusion with out unfavorable side-effect.
Care Regarding use of appropriate
1. Light forces and preparation of anchorage may prevent
extrusion of the posterior teeth.
2. The segmented arch technique to be superior in
preventing posterior dental extrusion during incisor
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
Indeed it is a daunting and challenging job to treat open
bite cases by now you will agree on that point I think.
“A thing started nicely is half work done” so taking this
guideline and putting meticulous attention to
biomechanics, I think we can very successfully treat the
very difficult open bite cases .
For more details please visit