Normal "scissor bite”

 

Malocclusions (bite abnormalities) are not uncommon in dogs and fall into 3 basic groupings:

1. Class 2A malocclusions
2. Class 3B malocclusions
3. Class 1 malocclusions

Class 2A malocclusions are commonly known as overshot bites (i.e. the top jaw is too long).

Overshot bite

 

The effect of this is for the lower canines (& sometimes the lower incisors as well) to impact into the soft tissues of the hard palate.  This is quite painful when the dog closes its mouth and can eventually lead to formation of oronasal fistulae (holes through the top of the mouth into the nose).

 

Damage from lower canines

 

Treatment for deciduous (baby) teeth is to extract the deciduous lower canines at around 3 months of age.  For the permanent teeth, height reduction of the lower canines and pulp capping is often the best alternative.

 

Height reduction and pulp capping

3B malocclusions (undershot bite – bottom jaw too long) are often purposely bred for e.g. boxers etc. 

Undershot bite

 

This does not mean that they cause no problems.  Careful examination of the lingual (tongue) side of the lower incisors will commonly show damage from the upper incisors and can be treated by extraction of the upper incisors.

Damage from upper incisors

 

Class 1 malocclusions are when there is some malocclusion but the jaw lengths are correct.  These include anterior cross-bite, caudal cross-bite, base narrow mandibular canines, displaced teeth, overcrowding and rotated teeth.  All of these can occur with 2A or 3B malocclusions as well.

 

Anterior cross-bite	Base narrow mandibular canines
Overcrowding, rotated teeth and displaced teeth

 

An uncommon malocclusion (but one which is often talked about) is the wry bite.  This is where one quadrant of the jaws is too long or (more commonly) too short compared to the other three.  This will cause a major distortion to the jaw alignment and often results in an open bite as well.

 

Wry bite