Anterior Open Bite Flashcards
what is the definition of an anterior open bite?
> absence of vertical overlap of upper and lower incisors
what is the incidence of an AOB?
> 2-4% of children
> 4% of adults
what is the signficance of an AOB?
> Dental appearance (But often not an issue)
> Functional difficulties: eating and speech
> Weak association with TMJ dysfunction
> Skeletal causes associated with “long face” and poor facial appearance
what is the aetiology of AOB?
- skeletal
> genetic
> TMJ trauma/ pathology - habits
> thumb sucking
> digit sucking - soft tissues
> macroglossia
> endogenous/ adaptive tongue thrust
> muscular dystrophy - Iatrogenic
> extrusion/ over eruption of molars during treatment or retention
what are the 3 classifications of AOB?
> Dental
> skeletal
> combination of skeletal and dental
what are the intra oral features of a dental AOB?
> Generally no unusual extra-oral features
> Usually limited to incisor region
> Features may be related to aetiology (eg. retroclined lower incisors and proclined upper incisors)
> Upper arch may be narrow
> Often due to Digit/Dummy sucking habits
when a dental AOB is due to a digit/ dummy habit, how does it present?
> Usually limited to incisor region
> Usually asymmetrical
> Retroclination of lower incisors
> Proclination of upper incisors, Class II Div 1
what is the incidence of thumb/ dummy sucking? and how many hours a day does it need to affect the teeth?
> Finger / thumb sucking = 15% children up to age 7 (7.5% continue after age 7)
> Dummy sucking = 50% children (1% after age 6)
> Severity of AOB depends on duration and intensity of the habit
> over 6 hours day for effects on teeth
what are the intra oral features of a skeletal AOB?
> In severe cases only the 7s may occlude
> Incisors usually normal inclinations
> Upper occlusal plane canted upwards
> Lower occlusal plane canted downwards
> Gingival hypertrophy due to mouth breathing
what is the extra oral features of a skeletal AOB?
> Long face
> Increased MM angle
> Lip incompetence
what is the cephalometric features of a dental AOB?
> may have a normal skeletal pattern
what are the cephalometric features of a skeletal AOB?
> reduced ramus height
> increased MM angle
> increased lower facial proportions
why do we treat an AOB?
> dental aesthetics
> functions
> facial appearance
what are the treatment options for AOB?
> “Interceptive”: stop digit sucking habits
> Orthodontics only: mild cases, dental AOB
> Orthodontics and Orthognathic surgery: severe cases, skeletal AOB
> Cases with a greater skeletal element are more difficult to treat
what patients with an AOB are suitable for fixed appliances only? and how is it carried out?
> For patients with acceptable facial appearance
> Best treated by specialist orthodontists
> Fixed appliances with elastics: extrude incisors
> High pull headgear to intrude upper molars
> Temporary anchorage device (TAD) intrusion of buccal segments
