Management of open bitedr

MANAGEMENT OF
OPEN BITE
Under supervision of
Dr Maher Fouda
Dr Alaa elkasaby
Professor of orthodontics
Mansoura Egypt

Definitions
 Open Bite( Negative Overbite):
- Inherited ,developmental or acquired maloccluison (vertical
occlusal anomaly) whereby no vertical overlap exists between
maxillary and mandibular anterior teeth ( anterior open bite-
AOB-)when posterior teeth are brought in to maximum
intertcuspation ,or no vertical contact is exhibited between
maxillary and mandibular posterior teeth (posterior open bite-
POB-).
- An open bite may be localized and thus involve only a few teeth
due to a digit sucking habit or other local factors(dental open
bite),or it may be caused by divergence of the skeletal planes
(skeletal open bite or apertognathia).

Anterior open bite.
Posterior open bite

Vertical overlap of Incisors
 Anterior open bite (AOB): there is no vertical overlap of the incisors when
the buccal segment teeth are in occlusion
 Posterior open bite (POB): when the teeth are in occlusion there is a space
between the posterior teeth
 Incomplete overbite: the lower incisors do not occlude with the upper
incisors or the palatal mucosa . The overbite may be decreased or increased
Increase Over
bite(o/b)
Normal o/b Incomplete o/b AOB

Classifications of Open Bite
 According to Moyers 1988 it can be classified in to:
1-Simple(Dental,functional) open bite :
Anterior or Posterior
2- Complex ( Skeletal) open bite:
which could be associated with
Class I ,Class II or Class III skeletal discrepancies

Classifications of Open Bite
A simple clinical diagnostic classification might be as follows:
1. anterior open bite with increased facial proportions
2. anterior open bite with history of digit sucking and normal facial
proportions
3. anterior open bite with no history of digit sucking and normal
facial proportions
EXCELLENCE IN ORTHODONTICS 2005

According to location:
1. Anterior open bite
2. Posterior open bite
• Unilateral
• bilateral
According to anatomical site involved:
1. Dental (simple)
2. Skeletal (complex)
3. Combined (skeletal, functional)

According to severity:
1. Pseudo open bite (open bite less than 1 mm).
2. Simple open bite ( anterior open bite more than 1 mm
but posterior teeth in occlusion)
3. Complex open bite ( extend from 2nd premolar on
one side to the 2nd premolar on the other side)
4. Compound open bite ( includes molars).
5. Iatrogenic open bite (improper orthodontic therapy)

Etiology :
 1- Transitional
 2- Skeletal
 3- Habits
 4- Soft tissues
 5- Trauma
 6- Iatrogenic
 7- Mouth breathing & Head posture
 8- Neurological disturbances.
 9- Localized failure of development
 10- Muscular dystrophy.

1-Transitional:
during eruption of teeth, patients are children in the
transitional dental stage, it is conceivable that the rate of
eruption of the anterior teeth will slow down temporarily.
These subjects are often referred to as having "transitional or
pseudo open-bite".

2-Skeletal:
Discrepancy in vertical development
Anterior & Posterior Backward Rotation (Bjork)
 Skeletal features:
- 1- Increased LAFH and there may be vertical maxillary excess
(supragnathism), ‘long face syndrome’ or Ricketts’ dolichofacial
type(1961) .
- 2- Steep mandibular plane & gonial angle.
- 3- Reduced posterior FH.
- 4- Divergent cephalometric planes (sassouni analysis)
In these cases AOB is usually symmetrical and in severe cases only
terminal molars contact.
Clinical Success in early orthodontic treatment 2005

The Frankfort Mandibular Planes Angle (FMPA) is usually increased.
In contrast to open bites caused purely by habit, in which there is
impedance of incisor eruption by the digit, in true skeletal open bite
incisor eruption may be increased in relation to the underlying basal
bone, although it still fails to compensate for the excessive vertical
development of the jaws.

Bjork identified seven structuralsigns
related to significantly abnormal
mandibular growth rotations:
1. inclination of the condylar head;
2. curvature of the mandibular canal;
3. shape of the lower border of the
mandible;
4. inclination of the symphysis;
5. interincisal angle;
6. interpremolar or intermolar angle;
7. lower anterior face height.
Dental Update – June 2003

3- Habits:
( Duration &
Intensity)
 Thumb sucking
 Digit sucking
 Dummy sucking( sucking the pacifier).

1. This open-bite is caused
by obstruction of eruption
of the anterior teeth.
Classically, this open-bite
is asymmetrical and fits
snugly around the
offending agent.
2. Many of these cases show
spontaneous remissions ,
and about 75 to 80% had
marked improvement
without any form of
treatment.

4- Soft tissues:
A - Tongue posture & Function:
All AOB exhibit anterior tongue thrust,but not all AOB are caused
by anterior tongue thrust.
Two Condition exists:
i- adaptive tongue thrust( secondary)
ii- endogenous tongue thrust (primary) rare
& difficult to distinguish

B-Lymphatic tissues:
 Large adenoid  Mouth breathing  Mandible postured
downward  separation of posterior teeth  over eruption 
increase in Lower Vertical Dimension  Open Bite
 The ‘Adenoid face’ consists of a narrow face, protruding teeth,
and lips separated at rest, and has often been attributed to chronic
mouth breathing.

5- Trauma (pathological) :
1. Bilateral fractured of the condyles.
2. Ankylosis of Condyles
3. Le Fort II and III fracture cases often present with gagging
occlusion, hence anterior open-bite.

6- Iatrogenic:
- This open-bite is produced by active orthodontic treatment
1- the use of anterior bite plane in already reduced overbite and the
extrusion of upper molars in high angle cases. Failing to prevent
overeruption of second molars when biteplanes or functional
appliances are used may also give rise to an AOB.
2-when High canines is engaged during alignment
3-Poor mechanics during fixed-appliance treatment may cause
extrusion of the molar teeth or ‘hanging’ palatal cusps, which
open the bite.

7- Mouth breathing & Head
posture:
--Mouth breathing (due to Nasal obstruction or Habit):
This doesn’t play significant role in the development of AOB
--Head posture :Related to breathing: mouth breathing  extension of
head  stretch muscles  increase vertical dimension
Studies have shown that when the nose is completely blocked,
there is usually an immediate change of about 5° in the
craniovertebral angle . The jaws move apart as much as the elevation
of the maxilla because the head tips back by the depression of the
mandible. This was described by Solow and Kreiborg as the soft tissue
stretching hypothesis.
International Journal of Paediatric Dentistry 2007

8- Neurological disturbances:
Neurological disorders contribute to the development of anterior
open-bite. Gershater demonstrated a very high incidence (32.3%) of
anterior open-bite in his survey of mentally retarded and emotionally
disturbed children. This supports other studies where problems in
controlling the tongue at rest or in function are
encountered.

9- Localized failure of
development:
In patients with cleft lip & alveolus ,although rarely it may
occur for no apparent reasons. Pathological conditions may also
present as anterior open-bite, such as in cleft palate,
acromegaly .

10 -Muscular Dystrophy
The decrease in tonic muscle activity that occurs in
muscular dystrophy allows the mandible to rotate
downwards away from the rest of the facial
skeleton, resulting in increased anterior facial
height, a posterior growth rotation of the mandible,
excessive eruption of the posterior teeth, narrowing
of the maxillary arch and AOB that worsens with
growth.

Posterior Open Bite
 A lateral open bite is occasionally seen in association with early
extraction of first permanent molars, possibly occurring as a
result of lateral tongue spread. Posterior open bite is also seen in
cases with submergence of buccal segment teeth.
An Introduction to Orthodontics , 2nd Edition 2001

 There are two rare conditions which affect the eruption of the
permanent buccal segment teeth:
1-Primary failure of eruption: this condition almost exclusively
affects molar teeth and is of unknown aetiology. Although bone
resorption above the unerupted tooth proceeds normally, the tooth
itself appears to lack any eruptive potential . Extraction is the only
treatment alternative. The aetiology is not understood.
2-Arrest of eruption: this also usually involves molar teeth. Affected
teeth appear to erupt normally into occlusion, but then subsequently
fail to keep pace with occlusal development. As growth of the rest of
the dentition and alveolar processes continues, lack of movement of
the affected tooth or teeth results in relative submergence . The
aetiology is not understood and again the usual treatment is
extraction of the affected tooth or teeth.
An Introduction to Orthodontics , 2nd Edition 2001

3-More rarely,
posterior open bite is seen in association with unilateral
condylar hyperplasia, which also results in facial asymmetry. If
this problem is suspected, a bone scan will be required. If the
scan indicates excessive cell division in the condylar head
region, a condylectomy alone, or in combination with surgery
to correct the resultant deformity, may be required.

Diagnosis of malocclusion with
skeletal open bite

Diagnosis of malocclusion cases with skeletal open bite:
1. Clinical examination
a) Extraoral
• Increased lower facial height.
• Steep mandibular plane
• Antigonial notching
• Large interlabial gap.
• Less prominent chin
• Long face
• Upper lip less than 1/3 of the lower facial height.
• High lip line
• Gummy smile.
b) Intraoral
• Anterior open bite extending posteriorly till premolar or molar areas
• Occlusal planes diverge
• Incisors extruded more than normal.
• Hypertrophic gingiva
• High narrow palatal vault
• Tongue thrusting during swallowing.

2. Cephalometric examination
a) Maxilla
• Increased anterior dentoalveolar height (incisal edge to palatal plane)
• Increased posterior dentoalveolar height (cusp tip to palatal plane)
b) Mandible
• Short ramus (normal 51.3)
• Increased gonial angle
• Marked antigonial notching
• Increased FmA (normal 25)
• Narrow symphesis anteroposterior and long vertically
• Increased anterior dentoalveolar height
• Increased posterior dentoalveolar height
c) Vertical relations
• Diverging SN, FH, occlusal, palatal, mandibular planes
• Maxillary occlusal plane steep upwards
• Mandibular occlusal plane steep downwards.
• Increased total facial hieght
• Increased lower facial height
• Reduced PFH

Diagnosis of malocclusion with
dental open bite

Diagnosis of malocclusion cases with skeletal open bite:
1. Clinical examination
a) Extraoral
• There may be an increase in vertical height.
b) Intraoral
• Charactreistic features related to the etiology
Thumb sucking: proclined upper incisors, narrow upper
arch, slightly deppressed lower incisors.
• Occlusion: open bite in incisor region
molars and premolars are in contact

Cephalometric examination:
a) Maxilla
• Upper incisors are proclined and may be spaced
• Dentoalveolar height at open bite region is reduced
• Dentoalveolar height otherwise increased
b) Mandible
• Lower incisors retroclined, crowded, or may be proclined
• Dentoalveolar height at open bite region is normal or may be
reduced
c) Vertical relation
• Thumb sucking resulted in paltal plane and mandibular plane
diverged away from each other at anterior region.
d) Anteroposterior relation
• Thumb sucking restrains anterior development of mandible and
encourage anterior development of maxilla increased incidence of
Class ll relation.

ODI(Overbite Depth Indicator)(Kim 1974):
American Journal of Orthodontics 1974; 65:586-611
The Angle A-B planes makes with the mandibular plane combined
with the angle of palatal plane to FH .
The angle formed by palatal plane and FH is either added (if
+ve)to or subtracted (if -ve)from MP/A-B plane
The angle is negative if palate is tipped down posteriorly or
positive if the palatal plane is tipped down in front
A value of less than 68 degrees is said to indicate over bite
tendency .

1-ODI(Overbite Depth Indicator) [Example]:
(MP-AB). (Example: 76°).
Measure the angle of the (FH), and (PP). In case of a positive value,
write it in the corresponding positive rectangle, otherwise, write it in
the corresponding negative rectangle (Example: -3°)
Combine these values to obtain the Overbite Depth Indicator (76°-
3°=73°). In this example the ODI is 73 degrees,which is slightly lower
than the norm (74.5° , 6°); howerver, the diference is 1.5°. Considering
the standard deviation, it falls within the normal limit with a sligth
tendency to be an openbite

Management of
Anterior Open Bite

Management of AOB
The key to the management of open bite
tendency:
1- Eliminate the etiology.
2- Avoidance of extrusion of posterior teeth.
3- Intrusion of molars rather than extrusion of incisors.
Treatment modalities:
1- No active treatment.
2- Habit breaker
3- Orthopedic appliances (myofunctional therapy)& Removable appliances
with bite blocks.
4- Fixed appliances.
5- Implants( microscrew ,miniplate)
6- Surgery (distraction osteogenisis & orthognathic surgery)
7- combination of two or more of the above.

Modalities of open bite correction
1. Skeletal open bite in growing patients
• Goals of treatment are : vertical control of molars, vertical
growth control, and this leads the mandible to rotate upword and
forward
• Vertical control of molars:
i. Direct : applying vertical forces directly to molars by using high
pull headgear in maxilla, or cervical pull headgear in mandible
ii. Indirect : applying vertical forces via occlusion by using:
 Occlusal splint (3-4 mm in thickness)
 Active vertical corrector
 Vertical holding appliance
 Chin cup with vertical pull.
iii. combination

• Treatment approach according to age
 During primary dentition
1. Habit control
2. Chin cup with vertical pull: redirect the growth forward and upward.
 During mixed dentition
1. Chin cup with vertical pull+posterior bite plane
2. High pull head gear+ acrylic splint
3. Functional appliance + high pull head gear
 During permanent dentition
1. Fixed orthodontic mechanotherapy : through molar intrusion, incisor
extrusion or combination, and includes
 MEA (multilooped edgewise apliance)
 EOF (extra oral force )on molars
 TAD (temporary anchorage device).
 RCS (reverse curve of spee) in upper arch

 Extrusion arch wires
 Stepped arch wires
 Repelling magnets
 Vertical inter maxillary elastics
 extraction
2. Skeletal open bite in non-growing patient
• Treated by fixed appliance mechano therapy
• Or orthognathic surgery

Treatment of dental open bite
During primary dentition
1. Habit control
2. Elemination of deforming muscle activity
 During mixed dentition
1. Habit control
2. Posterior bite plane
3. Myotherapy of the tongue
 During permanent dentition
1. Fixed mechanotherapy

1- No active treatment
 In this case treatment is aimed at relief of any crowding and
alignment of the arches. This approach can be considered in the
following situations (particularly if the AOB does not present a
problem to the patient):
1-mild cases.
2-where the soft tissue environment is not favourable, for example
here the lips are markedly incompetent and/or an endogenous
tongue thrust is suspected.
3-when anterior open bite is transitional due to partially erupted
incisor teeth
4-As first stage treatment in patients with sucking habits

2-Habit breaker
Proffit’s protocol
Dent Update 2003; 30: 235-241

2-Habit breaker
Designs:
 Palatal crib (Removable or
Fixed appliance)
 Tongue guard
 Quad helix
 Goal post
Crib appliance prevents suction in palate

Quad helix function with tongue/thumb
habit reminder
Quad helix with more aggresive habit
function

Vertical crib appliance traps tongue thrust
Dillingham I

Mandibular tongue thrust appliance Dillingham Habit

Bead appliance to train tongue to proper
position
Palatal crib with a bead to train
proper tongue position

3-Orthopaedic & Removable
appliances
 a-Posterior bite blocks, Twinblock, Elastic activator &
Active vertical corrector
 b- Frankel -4
 c- Extra-Oral traction: High pull headgear & Vertical pull
chincup.
 d- palatal crib and high-pull chin cup therapy

a-Posterior bite blocks, Twinblock, Elastic activator & Active vertical corrector

Highpull headgear to the biteblocks may increase their
efficiency. Where the AOB is associated with aClass II skeletal
pattern, a Twin Block appliance with highpull headgear can be
used to correct the anteroposterior discrepancy whilst controlling
the vertical dimension.
Dent Update 2003; 30: 235-241

Elastic Activator
A modified activator is used treatment of open bite
cases. The intermaxillary acrylic of the lateral occlusal
zones is replaced by elastic rubber tubes. By
stimulating orthopaedic gymnastics (chewing gum
effect), the elastic activator intrudes upper and lower
posterior teeth. A noticeable counterclockwise rotation
of the mandible was accomplished by a decrease of the
gonial angle.
a-Posterior bite blocks, Twinblock, Elastic activator & Active
vertical corrector
British Journal of Orthodontics/Vol. 26/1999/89–92

Elastic Activator

Kalra, Burstone and Nanda (1989) have suggested that
magnets may be beneficial in treating anterior open bites by:
• intruding upper and lower posterior teeth so as to allow
mandibular autorotation and
• distracting the condyle downwards and forwards to allow
compensatory condylar growth which would again favour
mandibular autorotation
Magnet-AVC (Active Vertical Corrector)

 Energized bite blocks. Energy is obtained from repelling
force of samarium cobalt magnets hermetically sealed In S.S.
capsule.

AVC
 Mode of Action:
Reciprocal intrusion of maxillary & mandibular teeth which result
in autorotation of mandible & overbite correction
Duration of wear  12 hrs/day
 Force level:
-700 gm per unit with 0 gap
-In open bite cases no 0 gap is present ,so force 600-650 gm per
unit
-Magnets are placed over the teeth to be corrected.
 Reported side effect: posterior crossbite owing to the lateral
force component of the repelling magnets.

b- Functional Regulator
Appliance Frankel (FR-4)
These are thought to be effective where the open bite is at
least partly due to faulty postural activity of the orofacial
musculature. The FR-4 works by allowing vertical
eruption of upper and lower incisors and retraction of the
maxillary incisors, and some authors have reported a
change in mandibular rotation from a downward and
backward direction to upwards and forwards.

The use of other functional appliances, open-bite bionators,
kinators, in the correction of anterior open-bites have also been
mentioned by some authors.

c- Highpull Headgear
Highpull headgear applied to the
maxillary molar teeth and worn for 14
hours per day has been used to inhibit
eruption of the posterior teeth and hence
limit vertical growth.
Headgear can be applied directly to the
upper molar bands of a fixed appliance
or use in conjunction with a functional
appliance or an upper removable
appliance such as a maxillary intrusion
splint. This form of treatment is based on
the assumption that over- development
of the posterior maxilla is responsible for
the deformity.

c- Highpull Headgear
Functional appliances used for Class II
maloclusions with increased vertical
proportions include the van Beek appliance
,it incorporate high-pull headgear and buccal
capping. In many cases fixed appliances are
then used to complete arch alignment,
together with extractions if indicated.

c-Vertical Pull Chincup
Vertical pull chincup therapy has been used to limit excessive vertical
growth. Pearson reported on 20 growing patients with backward
rotational tendencies treated by the extraction of four first premolars,
chincup therapy and fixed appliances. He showed that chincup therapy
was effective in reducing the angle between the maxillary and
mandibular planes and at closing all anterior open bites.

c-Vertical Pull Chincup
Mandibular autorotation was attributed to
reduction in the ‘wedging’ effect by premolar
extraction, retardation of eruption of posterior teeth
and redirection of condylar growth. However,
chincup therapy generally has poor compliance
rates and there is some concern that it may cause
condylar damage.

d-palatal crib and high-pull
chin cup therapy
Twelve months treatment with a palatal crib and chin cup
therapy resulted in the following changes:
1. Statistically significant extrusion of the incisors, as well as
an
increase in overbite and exposure of the maxillary incisors.
2. Greater uprighting and retrusion of the incisors, with a
statistically significant difference compared with the controls.
3. No statistically significant changes in the level of eruption
of
the molars, with no real or relative intrusion of these teeth.
4. No statistically significant skeletal changes, or significant
growth inhibition of LAFH, closure of the mandibular
plane angle or SNA/SNB modification.

HIERARCHY OF EFFECTIVENESS IN
LONG-FACE CLASS II TREATMENT

1- Intermaxillary elastics:
Anterior open bites can be closed using fixed
appliances and vertical intermaxillary elastics
to extrude the anterior teeth. This may be
combined with a transpalatal arch (TPA) and
highpull headgear to limit vertical development
of the maxillary molar teeth.
The TPA functions to prevent buccal rolling of
the first molars, which could cause the bite to
be propped open on their palatal cusps. Use of
anterior elastics may be successful in patients
in whom a digit-sucking habit has artificially
inhibited eruption, but is unlikely to work if the
aetiology is primarily skeletal.

Traditionally, vertical elastics
have been used for open bite
closure. Inter arch mechanics
with vertical elastics are indicated
in anterior open bite cases with
occlusal planes diverging
anteriorly. Vertical elastics from
the lower incisors to the upper
incisors result in a consistent
force system of equal and
opposite forces.
Force system of anterior
vertical elastics (equal and
opposite forces).

Although vertical elastics are a common method For
incisor extrusion, certain problems are inherent in this
type of treatment.
• First, response to this therapy varies greatly
among patients due to poor control of the force
magnitude and different degrees of compliance.
• Second, specific goals defined in the treatment
plan (occlusal plane, incisor position objectives)
can not be predictably achieved because good
mechanical control is difficult wilh indiscriminate
use of elastics.

 Correction of Open Bite with Elastics and
Rectangular NiTi Wires

Where anterior open bites are
associated with proclined
incisors, such as some
bimaxillary proclination cases
and Class II/I malocclusions,
retraction of the incisors results
in an extrusive movement, as the
crown is rotated around the
centre of rotation of the tooth.
This reduces/eliminates the open
bite. Stability depends on the
tongue adapting to a new
functional position after
treatment.
Dent Update 2003; 30: 235-241
2-Incisors retraction:

3. Extrusion Arches
 Extrusion arches are efficient tools used to correct upper and
lower occlusal planes that diverge anterior to the first
premolars.
 These archwires are indicated
(1) When spontaneous correction of an anterior open bite does
not occur following tongue crib therapy.
(2) When a constant extrusive force is desired in the anterior
teeth with minimal posterior side effects.
(3) In noncompliant patients who will not wear anterior vertical
elastics.

 The extrusion arch is a one-couple force system that applies
a single extrusive force in the anterior teeth, and a tip
forward moment and intrusive force to the posterior
segment. Often, the tip forward moment is undesirable.
Extrusion arch force
system; a one couple
system with ananterior
extrusive and a posterior
intrusive force. The couple
on the molar produces a tip
forward moment.

• First, to negate this side effect, a
buccal segment from the upper
first molar to the first premolar is
added.
• Second, the magnitude of the
extrusive force should be kept low
(extrusion of the incisors requires
very light forces) to maintain the
posterior moment at a minimal
level.
• Finally, adding vertical elastics off
the posterior segment to negate
this tip forward moment is also
helpful.
Vertical elastic added to
the upper buccal segment
to negate the tip forward
tendency produced by the
couple system in the
extrusion arch.

The extrusive force of an extrusion arch applied to
divergent occlusal planes anterior to the premolars is
favorable, especially if the upper incisors are flared. As
this force is applied labially to the center of resistance of"
the incisors, the moment of the force will produce an
uprighting movement (crown lingual).
Effects of the anterior force of
the extrusion arch on the upper
incisors. The applied force at the
bracket will produce at the
center of resistance of the
incisors a clockwise moment plus
an extrusive force of equal
magnitude.

This figure shows a patient with anterior open bite that
was corrected using upper and lower extrusion arches
Progress of a patient with extrusion arches on
the upper and lower dentition. A Frontal view on
smile. Only 50% of incisor show on smile.
Patient will benefit esthetically from upper
incisor extrusion, B-D Preoperative intraoral
photographs showing a 3 mm negative overbite
and an occlusal plane diverging anteriorly from
the first premolars.

E-G Upper extrusion arch with buccal segments to prevent
molar tip forward. The lower extrusion arch is tied to the four
incisors H-J Good anterior open bite correction with maintenance
of the vertical relationship on the buccal segments..

Upper extrusion arch used in conjunction with a light
nickel-titanium base arch. The extrusion arch maintains
the anterior vertical relationship as the canines are
brought into the arch.
Esthetically a good smile arc and
approximately 95% incisor display on
smile are achieved.

4- Extractions for Open Bite
Closure
Different types of extraction patterns have been suggested
to correct anterior open bites. These extraction patterns
include extracting: the second molars, first molars, second
premolars, or first premolars. The various extraction
modalities for the correction of an open bite are tailored
towards extruding the anterior segment, moving the
posterior teeth anteriorly (wedge effect). or a combination
of the two.

Second Molar Extractions
The extraction of second molars has
been suggested as a viable option in
patients who have an anterior open
bite with contact only on these teeth,
and divergent occlusal planes (wedge
effect).
Although this is a feasible option, the
magnitude of the occlusal plane
divergence is the limiting factor in
full overbite correction.

Anterior open bite with
occlusal planes diverging from
the second molars anteriorly.
All second molars are
extracted for correction of the
open bite. The magnitude of
the open bite correction is
dependent on the angle of
divergence of the upper and
lower occlusal planes. Full
correction of the anterior open
bite may not be obtained in
extremely divergent occlusal
planes.

• A potential problem, depending on the age of the
patient, is the necessary continuous monitoring of
the third molars until full eruption and correct
positioning in the arch is achieved.
• However, this method provides an advantage over
the other extraction patterns since no space
closure is needed and vertical forces are not likely
to be generated (see section on space closure in
premolar extract ions below).
• Interestingly, patients who present with this
anterior open bite pattern (divergent occlusal
planes with second molars only contacting) are
generally viewed as surgical patients.

First Molar Extractions
• First molar extractions are typically performed only if these
teeth are compromised by extensive decay. In theory, this
treatment alternative should contribute to anterior open bite
closure, and it has been reported that this extraction pattern
maintains or slightly reduces the vertical skeletal
relationships.
• However, in the majority of patients, the second molar
replaces the first molar and the anterior open bite is not
resolved. As the molar is protracted into the extraction space,
extrusion of the distal aspect usually results due to poor
mechanics, thereby increasing or maintaining the anterior
open bite

• Overall, if this extraction option is considered, space
closure mechanics is the deciding factor in the
success of the overbite correction, This treatment
alternative would be most effective if proper timing
is considered.
• If the second molars have not erupted, and if the
patient is only contacting on the first molars,
extraction of the first molars would eliminate the
increased vertical height and the second molars
would only be able to erupt up to the new
established vertical height

Extractions of Premolars
• Extractions of the first or second
premolars are the most
commonly considered procedures
for the treatment of anterior open
bites associated with crowding
and/or over jet.
• The decision between extracting
the first or second premolars
depends on the amount of incisor
retraction. in these patients the
open bite is closed with the help
of extrusion of the anterior
segment instead of the "wedge
effect."
Controlled tipping of the
upper incisors produced
by a distal force results
in extrusion of the
incisal edge and
reduction of the amount
of labial incisor
inclination.

• This treatment alternative works
very well in patients with occlusal
planes that diverge anteriorly
from the first or second premolar.
The mechanics are easier when
the anterior teeth are flared (as is
usually the case with this type of
occlusal plane divergence).
• A single distal force (ideally
controlled tipping) will produce
lingual tipping of the incisor
crowns. Since the center of
rotation is close to the apex, the
net effect is extrusion and
retraction of the incisors to close
the bite.

Biomechanics of Space Closure in Open Bite
Group A Space Closure
Group A space closure is most
difficult to perform in anterior
open bite patients if intraoral
anchorage is desired. The use
of differential moments to
maintain anchorage in this
force system results in a large
moment and an extrusive force
posteriorly. Differential moment force system in
group A space closure is unfavorable
for anterior open bite correction.
Vertical forces tend to accentuate
the open bite.

• Anteriorly a smaller moment
and an intrusive force are
generated. This force system
is highly undesirable in an
open bite patient.
• This figure shows that the
vertical forces are antagonistic
with this space closure
strategy.

• An alternative would be to use a
single couple system (intrusion
arch) where a couple is created at
the level of the molar and an
additional base arch (0.018 SS) is
placed for canine sliding
mechanics.
• The base arch would minimize the
intrusive force in the anterior
teeth while the intrusion arch
would contribute to anchorage in
the posterior end.

Group B Space Closure
• Mechanically, group B
space closure is the
simplest. No vertical forces
are generated and only two
equal and opposite moments
are needed.
• Careful monitoring is
essential to ensure that
equal moment/force ratios
are delivered to the anterior
and posterior segments.
Mechanics for group B anchorage
with equal and opposite moments is
favorable in anterior open bite
patients since no vertical forces are
generated. Adequate mement/force
ratios of 10/1 are desired
to prevent tipping of the posterior
segments that may accentuate the
open bite.

If a high force magnitude
in relation to the moment is
delivered in the posterior
end, excessive crown
lipping will result,
extruding the distal cusps
of the molar, and possibly
increasing the open bite.
Patient showing tipping of the
lower first molar and extrusion
of the distal marginal ridge.
Lateral open bite is developed.

Group C Space Closure
Group C space closure
mechanics is the most
favorable for anterior open
bite correction. Intraoral
anchorage by means of
differential moments obtains
a consistent force system.
Mechanics tor group C space
closure are the most favorable
for open bite correction.
Vertical forces are consistent
with open bite correction in the
anterior (extrusive) and
posterior (intrusive) segments

This Figure shows a larger moment in the anterior segment
and an extrusive force that will maintain the anteroposterior
incisor position. A smaller moment in the posterior and an
intrusive force will allow this segment to tip as a mesial force
is applied.

Anterior open bite closure by molar extractions and group C
mechanics. A Initial smile view showing an adequate amount
of incisor show. B Profile view showing a retrognathic
mandible and long facial height.

C-E Preoperative photographs showing molar-to-molar
open bite. All first molars have significant carious decay,
except for the upper left.

Initial lateral cephalogram showing a retrognathic mandible
with a skeletal anterior open bite and divergent occlusal
planes from molar to molar.

Differential moment approach for group C space
closure. A19 x 25 stainless steel base archwire from 5
to 5 is used as the anchor unit to protract the lower 7s
after extraction of the carious first molars. Sectional 17
x 25 CNA wires with a V-bend offset anteriorly (Class
V geometry) generate a larger anterior moment and
extrusive force, and a smaller moment and intrusive
force posteriorly. The sectional wire is connected to the
base archwire by a vertical tube soldered to a
horizontal tube.

Upper left first premolar extracted and upper canines
brought into the arch using equal and opposite forces by
means of an intermaxillary elastic.

Smile view showing unaltered incisor display and open
bite correction through molar vertical control as the
second molars were protracted S Profile view shows
the positive skeletofacial change with the mandibular
autorotation and reduction of the anterior facial height.

 Rationale behind choosing this
mechanics:
 Palatal plane is tipped upward
& forward with teeth tipped
mesially.
 Because of this ,treatment
should be directed toward
extracting the terminal molars
and distal tipping of the
dentition .
5- Multiloop Edgewise Arch
Wire(MEAW)
(Kim mechanics)

 This is usually achieved using
multi-loop edgewise archwires
made of 0.016× 0.022 S.S. wire.
5-L-shaped loops /side starting
from between lateral incisors and
canines and moving distally .
 Vertically ,loops should be 2-3
mm and horizontally it should be
5-mm except in molar region
where this increased to 8-mm

 Tip-back of 3-5 degrees are placed on each loop to
place a curve of spee(CS) on upper and reverse
curve of spee(RCS) in lower arches .3/16” or 1/8”
heavy elastics anteriorly will counter act the curve
of spee in upper and RCS in lower.

Although this method has proved successful, excellent
compliance with elastic wear is essential and long-term
stability has yet to be determined.

 More recently, the use of reverse
curve nickel-titanium archwire,
instead of multiloop wires, had
worked well.
 0.016× 0.022 NiTi (reverse curve
of spee RCS) in lower and
(accentuated CS) in upper arch.
 Heavy anterior elastics(3/16” 4.5
Oz) in canine region.
 At some stage ,molar become out
of contact , then flat 0.016× 0.022
S.S. wire is inserted and continue
with anterior elastics.
6-Recent modification of Kim
mechanics

Effects of MEAW & CS
 1- Retraction and extrusion of anterior teeth
 2- Up-righting & intrusion of posterior teeth
 3- Few skeletal changes

a. The RMI appliance provided
effective bite closure and
favorable dentofacial changes
for nonsurgical open bite
treatment in growing patients.
a. This method could be regarded
as a safe and non-compliance
alternative for early
intervention of skeletal open
bite correction.
7-Rapid Molar Intruder(RMI)
Appliance in Growing
Individuals

On the upper arch, in the event that one single
posterior tooth requires intrusion, two miniimplants
should be inserted, one buccally and one palatally, the
former on the mesial and the latter on the distal
region.The mini-implants, if placed accordingly, will
provide a controlled vertical movement without
undesirable inclinations.
Force can be applied either by
extending elastics between the
mini-implants and the orthodontic
accessories installed on the buccal
and palatal surfaces of the tooth in
question.
5-Microscrews

or by extending elastics directly on the tooth’s occlusal
surface and connecting one mini-implant to the other. In
this case, caution should be exercised not to allow the
force action line to cause the elastic to drift towards the
mesial or distal region, which might lead the dental unit
which is undergoing intrusion to tip.

B. Intrusion of groups of teeth
In the event of a group of teeth requiring intrusion, the
whole group should be handled all together in a group.
Brackets can be bonded to the buccal and palatal surfaces
of the teeth involved and connected with segmented
archwires; an orthodontic archwire segment can be
bonded directly to the buccal and/or palatal surfaces;
alternatively, a single orthodontic archwire segment can
be attached to the occlusal surfaces, provided it does not
cause any interference

The arch wire segments attached to brackets on the
buccal and palatal regions, activation can be achieved
using elastic on the archwire attached to the arch
segments.

Arch wire segments attached to brackets on the buccal and palatal
regions with an elastic chain running alongside the occlusal surface for
activation

Arch wire segments Bonded directly to buccal and lingual
surfaces while activation was done with an elastic chain running
alongside the occlusal surface

An arch wire attached to the occlusal surface while
activation was done with an elastic chain running
alongside the occlusal surface

5-Miniplates
 Titanium miniplates, offer stable
skeletal anchorage for intruding molars.
True intrusion of molars can be
accomplished in adults. The occlusal plane
angle of open-bite patients changes
accordingly. Anterior open bites can be
closed orthodontically by intruding
posterior teeth, resulting in reduced anterior
vertical face height, decreased mandibular
plane angle, and counterclockwise rotation
of the mandible.

American Journal of Orthodontics and Dentofacial Orthopedics December 2002

A-Microscrews & Miniplates
American Journal of Orthodontics and Dentofacial Orthopedics December 2002

A-Segmental alveolar distraction for the
correction of unilateral open-bite caused
by multiple ankylosed teeth
B- Tongue Reduction.
C-Orthognathic Surgery.

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