Anterior Open Bite
Etiology and Differential Diagnosis
Dr.Marwan Mouakeh, Consultant Orthodontist
Academic Adviser, Al-Hokail Polyclinic – Khobar ( KSA)

 OPEN BITE – Definition
• The term was coined by Caravelli in 1842 as a
distinct form of malocclusion.
• Anterior Open Bite ( AOB) may be defined as
the lack of incisal contact between anterior teeth
when the mandible is brought into full closure .

 OPEN BITE – Definition
• Anterior Open Bite ( AOB) may be also defined as :
the absence of vertical overlap of
the lower incisors by the upper
incisors ,when the posterior teeth
are in full occlusion .
• AOB can occur in all types of malocclusion.

Subtelny and Sakuda
Open Bite is a deviation in the vertical relationship of the
maxillary and mandibular dental arches.
It is characterized by a definite lack of contact , in the
vertical direction, between opposing segments of teeth.
 OPEN BITE – Definition

Anterior Open Bite
•The prevalence of dental open bites in the U.S Children is
approximately 16.5% in the black population and 3.5% in
the white population.
• The prevalence of simple anterior open bite decreases
until adolescence . Worms et al , 1971
 Prevalence
Kelly et al,1973
• Prevalence of AOB in the population ranges from
1.5% to 11% ( Zuroff et al, AJO-DO March 2010 )

 Prevalence
• Varies among races & with dental age
- At 6 years, 4.2% of children present with anterior
open bite, whereas at age 14 the prevalence decreases to 2% .
- Negative overbite ( > -2mm) occurs less than 1% of the US
population .
- AOB is 5 times more prevalent in Blacks (16.5% )than in
Whites(3.5% ) or Hispanics . Kelly et al, NCHS 1973
Anterior Open Bite

 Prevalence
•Open bites occur less than
deep bites
• The Demand for treatment is
approximately 17% .
Anterior Open Bite
Contemporary Orthodontics 4th edition , Proffit,Fields and Sarver. 2007

Prevalence of Anterior Open Bite
Malocclusion in a sample of Saudi
Orthodontic Patients
A Pilot study

Materials and Methods
• A pilot study on a sample of Orthodontic Population
• Evaluation of 500 Cephalometric Radiographs and
Tracings
• All subjects were Adults of Saudi origin
• Isolation of the anterior open bite (AOB) patients on
the basis of negative overbite .
Prevalence of Anterior Open Bite Malocclusion in a sample of
Saudi Orthodontic Patients

 Results
• Number of AOB cases = 48 (out of 500) or a
percentage of 9.6%
»Males = 20 (41.7 %)
»Females = 28 (58.3 %)
Prevalence of Anterior Open Bite Malocclusion in a sample of
Saudi Orthodontic Patients

Classification of Anterior Open Bite

Classification of Open Bite ( Worms,Meskin,and Isaacson )
 Simple OB : from canine to canine
 Compound OB: from premolar to premolar
 Infantile OB : from molar to molar.

Classification of Open Bite ( Cooke,1981)
 Skeletal OB
 Habit or Dental OB
 Abnormal Tongue Function OB
 Iatrogenic OB
 Pathological OB

 Classification of AOB
 Dental
 Dento-alveolar
 Skeletal
abnormal eruption of the incisors
change in the vertical growth of the
alveolar component
unfavorable vertical growth pattern

• Dentoalveolar with alteration in normal eruption of
anterior teeth( due to non-nutritive sucking habits ).
• Skeletal with long face caused by clockwise(backward )
rotation of the mandible .
• Skeletal caused by skeletal deformation such as
tipping of the maxilla and diversion of the gonial angle of the
mandible .
 Classification of Open Bite (K.Yamaguchi )
• K.Yamaguchi , in Nanda : Current Therapy in Orthodontics – 2010

 Classification and Types of Anterior Open Bite
Dentoalveolar SkeletalSkeletal
+
• K.Yamaguchi , in Nanda : Current Therapy in Orthodontics -2010

 Restricted to the anterior teeth
Normal facial &skeletal features
 Dentoalveolar Anterior Open Bite
 Classification and Types of Anterior Open Bite

 Skeletal Anterior Open Bite
 Backward and downward
rotation of the mandible
 Classification and Types of Anterior Open Bite

 Skeletal Anterior Open Bite
 Extending to the buccal teeth
Due to skeletal abnormality
 Associated with facial vertical
disproportion .
 Classification and Types of Anterior Open Bite

 Skeletal Anterior Open Bite
Excessive vertical growth
of posterior maxillary and
mandibular regions .
 Classification and Types of Anterior Open Bite

The etiology of anterior open bite malocclusion is
Multifactorial :
 Genetic and Hereditary factors
 Anatomic factors
 Environmental factors
Etiology of Anterior Open Bite

Genetic Factors Environmental Factors
Lower facial height is under
strong genetic influence.
Etiology of Anterior Open Bite
Abnormal functions and
altered soft tissues posture.

• Sbtelny & Sakuda (1964)
• The main cause of Skeletal Open Bite is an unfavorable
growth pattern with divergent basal bones .
Etiology of Anterior Open Bite
 Abnormal skeletal size
 Abnormal vertical growth pattern
 Increased tongue size .
 Genetic and Anatomic Factors

Etiology of Anterior Open Bite
 Genetic and Anatomic Factors
Abnormal skeletal growth pattern of the
maxilla & mandible, particularly the lower jaw.
 Skeletal Open Bite (Sassouni)
 Backward Mandibular Growth Rotation ( Bjork)
 Clockwise Rotation of the Mandible (Jarabak)
 Dolichofacial Pattern ( Ricketts)
 Hypedivergent Facial Pattern ( Schudy )
 Terminology

 Genetic and Anatomic Factors
•Unfavorable Growth Potential
- Steepness of mandibular plane
- Increased gonial angle
- Short mandibular ramus
- Increased anterior lower face height
- Backward rotation of the mandible.
Etiology of Anterior Open Bite

9,6y 24,6 y
Bjørk & Skieller,1983
•Backward Rotation
Arne Bjørk
1911-1996)
 Growth Rotations

•Inclination of the condylar head
•Curvature of the mandibular canal
•Shape of the lower border of the
mandible
•Inclination of the symphysis
• Anterior lower facial height
•Inter incisal angle
•Inter premolar , inter molar angle.
Structural signs of extreme
Growth Rotations

 Genetic and Anatomic Factors
Tongue size and Posture
- Macroglossia
- Lower tongue posture (at rest)
Etiology of Anterior Open Bite

Genetic and Anatomic Factors
Etiology of Anterior Open Bite
Muscular dystrophy
Neuromuscular deficiencies

Etiology of Anterior Open Bite
Genetic and Anatomic Factors
•The decrease in tonic muscle
activity that occurs in muscular
dystrophy allows the mandible to
rotate downwards resulting in
increased anterior facial height &
posterior growth rotation of the
mandible.
Muscular dystrophy

Etiology of Anterior Open Bite
• Amelogensis imperfecta

Genetic and Anatomic Factors
 Mandibular condyle resorption
- Local causes : example ( osteoarthritis ,
avascular necrosis ,traumatic injuries…)
- Systemic causes : example ( rheumatoid
arthritis …)
Etiology of Anterior Open Bite

Idiopathic condylar resorption
 Most common in TMD adolescent patients
( particularly in females )
 Affects mandibular condyles bilaterally
 No obvious etiology ( DD Without reduction, joint
hypermobility , trauma , parafunctional activity,
decreased levels of estrogen….).

•Idiopathic condylar resorption
Etiology of Anterior Open Bite
- may induce a “sudden open bite “

•Idiopathic condylar resorption may induce a “sudden open bite “
Etiology of Anterior Open Bite

Etiology of Anterior Open Bite
Genetic Factors Environmental Factors
•Anterior (and low) tongue posture
at rest
• Prolonged thumb or finger sucking
• Tongue thrust
• Mouth breathing
• Atypical deglutition
• Weak masticatory muscle forces

Environmental Factors
Etiology of Anterior Open Bite

Environmental Factors
 Habits
- Pacifier and Thumb sucking habits
- Tongue thrust
- Infantile deglutition ( swallowing )
Etiology of Anterior Open Bite

Etiology of Anterior Open Bite
Environmental Factors
•Thumb & Pacifier sucking habits

•Pacifier and Thumb-sucking habits are strong
etiologic factors for open-bite malocclusion .
Etiology of Anterior Open Bite
Environmental Factors
G. Janson &F.Valarelli , Open –Bite Malocclusion Treatment and Stability . 2014

•Anterior open bite caused by the use
of pacifier is characterized by being
restricted to the anterior region of the
dental arches and circular .
Etiology of Anterior Open Bite
G. Janson &F.Valarelli , Open –Bite Malocclusion Treatment and Stability . 2014

Environmental Factors
 Non-Nutritive Sucking Habits
Etiology of Anterior Open Bite

Environmental Factors
Etiology of Anterior Open Bite
• Thumb and Finger Sucking (Non-Nutritive Sucking )
- Major cause of AOB in young children
- 10% -15% of children tend to continue sucking habit
after age 10 .

•Thumb-sucking habit
characteristically causes labial
inclination of maxillary incisors
and lingual inclination of
mandibular incisors .
Environmental Factors
Etiology of Anterior Open Bite

Environmental Factors
 Non-Nutritive Sucking Habits
Etiology of Anterior Open Bite
Asymmetric AOB

Environmental Factors
• Abnormal tongue function
Etiology of Anterior Open Bite
Anterior Tongue Thrust , Tongue Sucking

Environmental Factors
Etiology of Anterior Open Bite
Airway obstructions ( Mouth Breathing )
- Enlarged adenoids and tonsils
- Swollen nasal turbinates
- Deviated nasal septum
- Inflammed nasal mucosa

Upper Airway Obstruction
Mouth Breathing
Low Tongue & Mandibular Posture
Supra-eruption of Posterior Teeth
•Enlarged Adenoids
•Enlarged Tonsils
•Deviated nasal septum
•Swollen nasal turbinates

 No clear –cut relationship between Breathing and
Malocclusion :
 Total nasal obstruction is highly likely alter the pattern of growth
and lead to malocclusion in experimental animals and humans
But , the majority of individuals with long face have no evident
nasal obstruction .
Etiology of Anterior Open Bite

11 yrs. 17 yrs.
• Airway Obstruction
Great controversy regarding the real effect on facial growth pattern
•Decrease in adenoid volume and enhancement of “ airways
patency ” with growth and maturation.

Low and anterior tongue posture
may be considered as the key
etiological factor in AOB .
• Abnormal tongue posture
Etiology of Anterior Open Bite

 If Postural change of the tongue lasts long ,
 Maxillary arch becomes narrow
 Molars passively super-erupt
 Mandible rotates clock-wise
 Anterior facial height increases
 Overjet increases

Etiology of Anterior Open Bite
• Abnormal tongue posture
 Enlarged tonsils Low & forward tongue positioning

Low and anterior tongue
posture may cause:
- infra-position of the anterior
teeth
- over-eruption of posterior
teeth
- upper arch constriction .
• Abnormal tongue posture
Etiology of Anterior Open Bite

Etiological Factors and Morphological Features of Open Bite
• K.Yamaguchi , in Nanda : Current Therapy in Orthodontics

Etiology of Anterior Open Bite
Environmental Factors
•Disturbance in the eruption of the
teeth & alveolar growth due to
trauma causing ankylosis of
anterior teeth .

Etiology of Anterior Open Bite
Environmental Factors
•Severe crowding of anterior
teeth
• Arrested tooth eruption
(Idiopathic or Iatrogenic )

•Iatrogenic Open Bite:
In the consequence of orthodontic therapy where
poor mechanics can cause extrusion of the molar teeth
or hanging palatal cusps which open the bite.
Failing to prevent over-eruption of second molars
when biteplates or functional appliances are used will
give rise to an open bite.
Etiology of Anterior Open Bite
Environmental Factors

Etiology of Anterior Open Bite
Environmental Factors
•Iatrogenic Open Bite

•Temporomansibular Pain & Dysfunction may cause
resorption of the mandibular condyle which in turn induce
open bite malocclusion.
• TMD problems and Open bite make bite force weaker.
• The weaker is the bite force , the severer becomes the
open bite .This makes a vicious cycle.
JW Han & TW Kim,2006
Etiology of Anterior Open Bite

• JW Han & TW Kim,2006
Etiopathogenesis of open bite in TM Dysfunctions

• Some Etiological Factors of Open bite Malocclusions
• JW Han & TW Kim,2006

Anterior Open Bite
Diagnostic Considerations

Dentoalveolar Open Bite
•Main Feature
•Proclined upper anterior teeth
•Lack of overlap between the upper and lower anterior
teeth.
•Narrow Maxillary Arch (Low Tongue Posture)

Dentoalveolar Open Bite
Main Features
• Normal facial proportions
• Associated with anterior tongue thrust during swallowing
and lisping .

Dentoalveolar Open Bite
•Main Cephalometric Feature
•Proclined upper anterior teeth
•Infraposition of the anterior teeth
• Reduced anterior dentoalveolar height

 Characteristics of Dental Open Bite
 Normal craniofacial pattern
 Proclined incisors
 Undererupted anterior teeth
 Normal or slightly excessive molar height
 Divergent upper and lower occlusal planes
 Absence of remarkable cephalometric findings
 Thumb or finger sucking habits
 Tongue thrusting habit

 Skeletal Open Bite

 Main Clinical Characteristics
Skeletal Open Bite
• Excessive anterior face height ,
particularly in the lower third
• Lip incompetence
(interlabial gap > 4mm)
• Anterior open bite ( not always)
•Tendency to Class II malocclusion with
mandibular deficiency
• Tendency to posterior cross bite due to
narrow maxilla.

• Main Facial and Occlusal Features
• Lip Incompetency
• Large Interlabial gap at rest
Key soft tissue finding
 Skeletal Open Bite

 Skeletal Anterior Open Bite
Severe &extended open bite
including the posterior teeth.

•Dentoalveolar OB ,vs, Skeletal OB
 Divergence of occlusal planes
Dentoalveolar Open Bite Skeletal Open Bite

 Skeletal AOB : Occlusal planes generally diverge from the 1st molar anteriorly
Occlusal characteristics of Skeletal and Dental Open Bites
 Dental AOB : Occlusal planes generally diverge from the premolar anteriorly

Cephalometric Characteristics
Skeletal Open Bite

• Proportional discrepancy between anterior and
posterior facial heights
 Mechanism of Skeletal Open Bite (K.Yamaguchi )
•Any elongation of posterior
teeth will induce a clockwise
rotation of the mandible
+
+

 Main Cephalometric Characteristics
Skeletal Open Bite
• Increased anterior face height
and decreased posterior face
height
• Steep mandibular plane with
short ramus
• Increased anterior lower facial
height
• Upper tip of the palatal plane
• Excessive eruption of maxillary
posterior teeth .

Common Cephalometric Indicators
for Skeletal Open Bite
• SN- MP
• FH-MP
• PP-MP
• Y-axis angle
• Gonial angle
 Sagittal Angles
•Lower Gonial Angle
LGA
FH
SN
MP
PPY-Axis

•Mandibular Plane angle > 36⁰
Key skeletal finding associated with anterior skeletal
open bite cases .
SN/ MP > 36⁰
 Skeletal Open Bite

•Anterior face height : increased
•Ratio : PFH / AFH < 62%
(Jarabak )
• Ratio : AUFH / AFH < 45%
•Ratio : ALFH / AFH > 55%
Me /
Skeletal Open Bite
Main Cephalometric Indicators
AUFH / ALFH < 70% - 65%
( Nahoum ,1975)

Kim, 1974
Overbite Depth Indicator (ODI) = ( A-B plane/ MP )⁰ + ( FH/PP)⁰
Mean = 74.5⁰ ± 6⁰
Skeletal Open Bite

 Overbite Depth Indicator (ODI)
• ODI ≤ 68 ⁰ Skeletal OB Tendency
Skeletal Open Bite
A-B Plane
FH
MP
PP

•Structural signs of mandibular
growth rotation demonstrated on
two craniums one with basal deep
bite and one with basal open bite.
 A . Bjork,1969

•Morphological signs of backward mandibular growth rotation
( Bjork , Skieller and Linde-Hansen)
•Anterior facial height Increased
•Inclination of lower border Notched
of the mandible
•Inclination of symphysis Slopes forward
•Inclination of the condyle Straight or slopes back
•Curvature of mandibular Straight
canal
•Intermolar angle Acute
•Internincisal angle Acute
Backward rotationMorphological sign

• Sassouni, 1969
Classification of Facial Types

•Ratio : PFH / AFH
•Ratio : UFH / LFH
•SN/ GoGn angle
•Gonial angle
•SN / PP angle
• PP/ GoGn angle
The angles and ratios remained relatively constant with age.
T J Cangialosi,
Cephalometric Features of Skeletal Open Bite

• Result showed a significant increase in :
 AFH
 MP angle
 Gonial angle
 Y-Axis angle
 Mandibular occlusal plane/SN angle
 Interincisal angle
 A significant decrease in maxillary length , and retruded
position of both the maxilla and the mandible relative to SN
plane .
 Cephalometric features of anterior open bite
SM Taibah & RM Feteih , 2007
•Cephalometric evaluation of 111 ( 58 females,53 males )
subjects of Saudi origin with anterior open bite .

 No Significant differences in all dental heights between
open-bite and control subjects.
 Open bite malocclusion is largely due to changes
in the skeletal pattern .
 Cephalometric features of anterior open bite
SM Taibah & RM Feteih , 2007

Open bite malocclusion: Analysis of the underlying components
M. El-Dawlatly et al, Dent Oral Craniofac Res,2015
The Percentages of occurrence of all components in open bite malocclusion.

The Percentages of occurrence of skeletal components in open bite malocclusion.
Open bite malocclusion: Analysis of the underlying components
M. El-Dawlatly et al, Dent Oral Craniofac Res,2015

The Percentages of occurrence of dental components in open bite malocclusion.
Open bite malocclusion: Analysis of the underlying components
M. El-Dawlatly et al, Dent Oral Craniofac Res,2015

Open bite malocclusion: Analysis of the underlying components
M. El-Dawlatly et al, Dent Oral Craniofac Res,2015
 High contribution of skeletal factors in the development of
open bite malocclusion.
 The increased downward and backward rotation of the
mandible is the highest sharing skeletal variable .
 The reverse curve of Spee and the proclination of the
upper incisors are the highest sharing dental factors in open
bite malocclusion.
Conclusions

 Skeletal Open Bites : main skeletal etiologies
PFH/AFH > 65%
PFH/AFH > 65% PFH/AFH > 65%
PFH/AFH =62%-65%
Normal maxillomandibular relation
PFH /AFH < 62%
PFH /AFH < 62% PFH /AFH < 62%

Aleppo , Citadel – SYRIA

Anterior Open Bite
Treatment in the Deciduous
and Mixed Dentitions
Next : Part 2 ….
Dr.Marwan Mouakeh, Consultant Orthodontist
Academic Adviser, Al-Hokail Polyclinic – Khobar ( KSA)