increased overbite/ Class II div 2 Flashcards
what is the definition of an overbite?
> overlapping of the upper anterior teeth over the lowers in a vertical plane
> normal value = 3-4mm
what is the definition of an increased overbite?
upper incisors overlap lowers by more than 4mm
what is a reduced over bite?
> less than 3mm overlap
what is the significance of an increased overbite?
> Trauma – soft tissues of anterior palate
> Prevents overjet reduction during treatment
> Dentofacial aesthetics
> Restorative difficulties
what are the extra oral features of an increased overbite?
> reduced lower face height
> often class II skeletal relationship
what is the incidence of increased overbite?
> Increased overbite is a feature of many malocclusions
- Most Class II Div 2 malocclusions
- Many Class II Div 1 malocclusions
- Some Class III and Class I malocclusions
what is the aetiology of an increased overbite?
> AP skeletal discrepancy (Class II, III)
> Increased interincisal angle (Class II Div2)
> Reduced lower face height
> Unopposed lower incisors - can cause trauma
why do we treat an increased overbite?
> Allow overjet reduction
> Facilitate a Class I incisor relationship
> Improve post-treatment stability
> Facilitate restorative treatment
how do we reduce an increased overbite in growing patients (eg <14)
> Anterior Biteplane
> Functional Appliance (eg. Andresen, Twinblock)
> Fixed appliances
how do we reduce an increased over bite in non growing patients (>14)
> Orthognathic surgery often required
> Sometimes fixed appliances alone
> Therefore refer deep bite patients early
what are the key features in an anterior bite plane in the treatment of growing patients with an increased over bite?
> Biteplane only contacts with lower incisors
> Posterior mandibular rotation
> Eruption of molars due to separation
> has no active component
what are the key features of functional appliance in treatment of an increased over bite?
> for Class II Div 1 malocclusions
> Anterior biteplane effect = the posterior teeth are separated vertically when wearing the appliance allowing eruption
> Trimming posterior inter-occlusal acrylic allows eruption of posterior teeth
> This also facilitates full overjet reduction
how does fixed appliance reduce an increased overbite?
> Overbite reduction is mostly due to molar extrusion
> Some incisor intrusion is possible, apical force can cause small amount of vertical movement
what is the definition of Class II div 2 malocclusion ?
> Lower incisor edges are palatal to the cingulum plateau of the upper incisors and the upper central incisors are retroclined.
> The overjet is usually average but may be increased
what is the incidence of class II div 2 malocclusion in the population?
> 5-10%
what is the extra oral features of a class II div 2 malocclusion?
> skeletal II relationship
> reduced lower face height
what are the intraoral features of Class II Div 2 malocclusion?
> Retroclined upper (and lower incisors)
> Increased inter-incisal angle
> Deep overbite
what is the cephalometry for class II div 2 malocclusion?
> Upper incisors retroclined
UI / Mx < 105º
> Often Class II skeletal
ANB > 4º
> Increased overbite
> Reduced lower facial proportions
what is the significance of a class II div 2 malocclusion?
> Poor dental appearance
> Traumatic overbite
> Reduced lower face height
what is the treatment aims of a class II div 2 malocclusion?
> Relieve crowding and align arches
> Reduce overbite
> Produce a stable incisal relationship
> Improve facial profile
what are the treatment options for class II div 2 malocclusions?
- Fixed appliances
- Often also use URA to help overbite reduction - Fixed Appliances + Surgery
what type of movement do fixed appliances allow us to do while treating class II div 2 cases?
> Torqueing
> root control required to upright and then bodily retract upper incisors
which class II div 2 malocclusion cases suitable for treatment with fixed appliances?
> Crowded upper arch requiring extractions
> Crowded lower arch requiring extractions and alignment
> Acceptable facial profile
> Only in growing patients if there is a deep overbite
what is common treatment plan for someone requiring treatment for a class II div 2 malocclusion?
> Anterior biteplane usually used with fixed appliances to reduce the overbite
> Usually extract upper 1st premolars
what are the stages of treatment for a class II div 2 malocclusion with fixed appliances?
- stage 1 - overbite reduction - An upper removable biteplane and lower fixed appliance is an efficient way to reduce a deep overbite
- stage 2 - torquing upper incisors
which cases of CII div2 are suitable for surgical treatment?
> Adult patients (non-growing)
- too old for functional appliances
> Poor facial profile
- vertical: reduced lower face height
- AP: Class II skeletal pattern
> Deep overbite
what are the stages of surgical class 2 div 2 malocllsuion?
- Correction of incisor inclinations
using fixed appliances - Surgical correction of jaw relationship
what is the prognosis of class II div 1 malocclusion treatment?
> Stability depends on correction
of the inter-incisor angulation
> Must achieve Class I incisors
