Anterior Open Bite

Copyright (c) By Dr. Hla Hla Yee
Department of Orthodontic Dentistry, University of Dental Medicine

1. Anterior Open BiteAnterior Open Bite
Dr.Hla Hla Yee

2. Anterior Open Bite
The absence of any vertical incisor
overlap between the upper and lower
incisors.

3. CausesCauses
( 1 ) Skeletal causes( 1 ) Skeletal causes
  
–Excessive vertical growth of maxilla often Excessive vertical growth of maxilla often
more posteriorly than anteriorly and more posteriorly than anteriorly and
posterior growth rotation of the mandible.posterior growth rotation of the mandible.

5. Clinical FeaturesClinical Features
  
–Incerased lower facial height Incerased lower facial height
–Increased maxillary-mandibular plane Increased maxillary-mandibular plane
angleangle
–Increased Frankfort-mandibular plane Increased Frankfort-mandibular plane
angleangle
–Obtuse gonial angleObtuse gonial angle
–Upward slope of the maxillary plane Upward slope of the maxillary plane
–Steep mandibular planeSteep mandibular plane
–Short mandibular ramusShort mandibular ramus

6. ( 2 ) Dental causes( 2 ) Dental causes
–Excessive eruption of posterior teethExcessive eruption of posterior teeth
–Incisors eruption is impededIncisors eruption is impeded
  

7. ( 3 ) Soft tissue( 3 ) Soft tissue
–Decrease in tonic muscle activity that Decrease in tonic muscle activity that
occur in muscle dystrophy , cerebral palsy occur in muscle dystrophy , cerebral palsy
muscle weakness syndrome.muscle weakness syndrome.
–Therefore – the mandible drops downward Therefore – the mandible drops downward
from the rest of the facial skeletal.from the rest of the facial skeletal.
–Therefore - excessive eruption of Therefore - excessive eruption of
posterior teeth and narrowing of the posterior teeth and narrowing of the
maxillary arch and anterior open bite.maxillary arch and anterior open bite.

8. ( 4 ) Habit( 4 ) Habit
–Tongue thrustTongue thrust
–Thumb suckingThumb sucking
–Mouth breathingMouth breathing

9. ( 5 ) Others( 5 ) Others
Localized failure of maxillary dento-alveolar Localized failure of maxillary dento-alveolar
development resulting in an open bite is development resulting in an open bite is
seen in clefts lip and palate.seen in clefts lip and palate.
Hemimandibular hypertrophy – excessive Hemimandibular hypertrophy – excessive
growth of mandible, the dental occlusion growth of mandible, the dental occlusion
shows open bite on the effected site.shows open bite on the effected site.
  
  

10. ( 6 ) Combination( 6 ) Combination

11. TreatmentTreatment

12.   
For skeletal open biteFor skeletal open bite
In mild case, In mild case,
–case align arches and accept ( or )case align arches and accept ( or )
–try to restrain vertical development of try to restrain vertical development of
maxilla and /or upper molars with maxilla and /or upper molars with
headgear ( or ) functional appliance with headgear ( or ) functional appliance with
posterior bite blocks.posterior bite blocks.
–Extrusion of incisors is unstable.Extrusion of incisors is unstable.

14. In more severe case In more severe case
surgery or combined treatment.surgery or combined treatment.

15. For dental open biteFor dental open bite
–Intrusion of posterior teeth or extrusion of the Intrusion of posterior teeth or extrusion of the
labial segment by usinglabial segment by using
( 1 )( 1 )High pull headgear to the upper molars is High pull headgear to the upper molars is
the best approach if excessive vertical the best approach if excessive vertical
development of the posterior maxilla.development of the posterior maxilla.
This treatment will have to continued This treatment will have to continued
until growth is nearly complete, until growth is nearly complete,
usually well into a retention period.usually well into a retention period.

16. The headgear to the maxillary molars The headgear to the maxillary molars
directing the force upward as well as directing the force upward as well as
posteriorly. The effect of this, in patients posteriorly. The effect of this, in patients
who are still actively growing, is simply to who are still actively growing, is simply to
inhibit the eruption of posterior inhibit the eruption of posterior teeth, teeth,
allowing the anterior segment to catch up.allowing the anterior segment to catch up.

17. ( 2 ) Interocclusal bite blocks is ( 2 ) Interocclusal bite blocks is
controlled the eruption of lower teeth.controlled the eruption of lower teeth.
( 3 ) bite blocks incorporating repelling ( 3 ) bite blocks incorporating repelling
magnets to facilitate posterior magnets to facilitate posterior
tooth intrusion.tooth intrusion.
  

18. ( 4 ) Fixed appliances and vertical ( 4 ) Fixed appliances and vertical
intermaxillary elastics.intermaxillary elastics.
( 5 ) Open bite associated with icreased ( 5 ) Open bite associated with icreased
labioversion of the incisors labioversion of the incisors
( Bimaxillary )( Bimaxillary )

19. Deep Bite
( Increased Overbite )
Excessive overlap of the anterior teeth

20. CausesCauses
( 1 ) Skeletal cause – ( short face ) due to increased ( 1 ) Skeletal cause – ( short face ) due to increased
posterior facial height (long mandibular ramus, posterior facial height (long mandibular ramus,
mandible rotates upward and forward direction).mandible rotates upward and forward direction).
Clinical FeaturesClinical Features
–Reduced lower facial heightReduced lower facial height
–Short nose – chin distanceShort nose – chin distance
–Low mandibular plane angle Low mandibular plane angle
–Flat mandibular plane Flat mandibular plane
–Low maxilary – mandibular plane angleLow maxilary – mandibular plane angle
–Acute gonial angleAcute gonial angle

21. ( 2 ) Dental cause – due to
a. Supra-eruption of lower incisors and
infra-eruption of the molars.
Therefore, Curve of Spee is exaggrated.
b. Retroclined incisors
–Increased interincisal angle
( Average 130 degree ) Range 125-135 degree
–Above this value the tendency for the lower
incisors to erupt may be inadequately resisted.

22. ( 3 ) Soft tissue
–Due to high lip line. Therefore the upper
incisors are retroclined.

23. TreatmentTreatment
( 1 ) For skeletal deep bite

28. ( 2 ) For dental cause
–( 1 ) Extrusion ( eruption of molars )
Passive eruption of lower molars
An anterior bite plane is incorporated into a
removable appliance so that the mandibular
incisors occlude with the plastic plane lingual
to the maxillary incisors.
This approach prevents the posterior teeth
from occlusion and encourages their eruption.
Active extrusion of molars – in either
arch is possible by using a fixed – appliance.

29. –( 2 ) Intrusion of incisors
( a ) Absolute intrusion
Absolute intrusion of the upper and lower
incisors moving their root apices closer to the
nose and lower border of the mandible
respectively.
In the absence of growth, the absolute
intrusion and extrusion are possible.
( b ) Relative intrusion
Achieved by preventing eruption of incisors
while growth provide vertical space into which
the posterior teeth erupt.

30. Absolute intrusion

32. Extrusion
Relative intrusion
( growth required )

33. Utiity arch

34. –( 3 ) Proclination of lower incisors.
– ( 4 ) Proclination or proclined upper
incisors – relative extrusion of incisor
teeth may be accomplished as a result
of reangulation by FA or RA.
If space required for reangulation, extraction
may also be necessary to provide sufficient
space for retraction.