MASTICATION

At rest the lower incisors locate between the front upper incisors and peg teeth, and there is a slight gap between the upper and lower molars. As the rabbit starts to eat its jaw opens slightly, grasping and then slicing the food between its upper and lower incisors in a scissor-like action. The tongue moves the food back towards the cheek teeth on one side. A slight retraction and sideways movement of the lower jaw brings the occlusal surfaces of the cheek teeth into contact on that side, the incisors being separated by this action, and the food is ground by a rapid side to side chewing motion (~200 cycles / min). Fibrous and abrasive materials such as grass and hay (containing silicates and other minerals) are required to wear the tooth surfaces and keep the continuously growing cheek teeth at the correct length.

MALOCCLUSION

When upper and lower teeth are correctly aligned they are said to be in normal 'occlusion'. Conversely, 'malocclusion' describes the condition where the teeth or jaws fail to align properly. The causes of malocclusion may be:

• Traumatic - physical breakage (tooth or jaw), loss of a tooth, dislocation of one or more teeth or the jaw, separation of the mandibular symphysis
  

• Atraumatic - congenitally absent or mal-positioned teeth, hereditary jaw deformity (some dwarf and lop-eared breeds), tooth overgrowth, dietary influences, disease, infection, toxicity or abnormal chewing habits

DENTAL OVERGROWTH

The teeth continue to grow (being open-rooted) whether or not there is normal wear. If the rate of eruption exceeds wear, the crown gradually elongates. A slight increase in occlusal pressure can tip and rotate the crowns. It may also arrest eruption, forcing the roots to grow backwards into the surrounding tissues (root elongation).

Malocclusion of the incisors can prevent closure of the mouth resulting in a secondary malocclusion of the molars. The reverse situation can also occur, whereby overgrowth of the molars prevent the mouth from closing fully causing the incisors to overgrow.

Russel Rabbit 

Dental Structure

Overgrown Incisors