Rabbit's teeth grow continuously throughout life, and are worn down continuously by grinding against each other. The teeth overgrow when this system fails.
There are two sets of teeth to consider, the front ' bug's bunny' teeth, called the incisors, are used for nibbling food into smaller pieces and for grooming. These teeth are easily examined and should be even, with a slight inwards curl, the tips being sharpened as the upper incisors wear against the lower ones. The tooth root is as long as the visible crown and ends at the active growth bulb of the tooth. These teeth can be misaligned at a very early age in some family lines and will require regular trimming. Often this can be achieved without anesthetic and should preferably be with a small diamond burr to prevent vertical cracking of the enamel. Vertical cracks can run right to the bulb allowing infection and dental abscess formation. If bunny has hereditary problems with the incisors, the cheek teeth may be perfectly normal and so extraction of the deformed front teeth provides a permanent solution to dental overgrowth. Incisors may become misaligned if one is broken by biting hutches or fighting with companion rabbits. Often though they fail to grind as part of more general dental disease involving the cheek teeth.
The cheek teeth, or molars, can be examined in most rabbits without difficulty by using a cone and light source ( commonly the otoscope usually intended for examining ear canals)but require heavy sedation or a general anesthetic to be trimmed. Most molar overgrowth is the result of inappropriate nutrition and lack of access to sunlight. Many commercial rabbit foods appear like muesli and many rabbits, like most humans, have favorite bits! If the food is replenished daily without the whole ration having been eaten, selective feeding causes mineral imbalance. This, coupled with inadequate sunlight to activate Vitamin D, causes gradual softening of the facial bones and the molars begin to tilt. As the molars tilt they can no longer wear evenly and spikes appear, cutting into the cheek or tongue. This discomfort further reduces appetite and so chewing activity. Excess salivation and weight loss soon follow. Often there is overflow of tears as the tear duct is compressed by deformed molar roots. The molar enamel will crack and deep molar abscesses form causing swellings along the upper or lower jaw line. Treating these dental abscesses is frequently unsuccessful as the bone has become infected and drainage of the thick pus and dead tissue, without tooth root damage, often impossible.
Rabbits need to chew plenty of long fiber, hay and grass for example. A complete pelleted diet of compressed grasses is the ideal foundation and then fresh 'treats' of carrots and weeds are excellent for providing variety. If a mixed 'muesli' diet is used, be sure that the dish is not overfilled so that ALL of the ration is eaten to make sure the diet is balanced. And lastly be sure to allow bunny to get out into the sunshine. Sunlight is needed on the skin to activate vitamin D so that minerals can be transported into bone to maintain a strong jaw and reduce the risks of teeth tilting and wearing unevenly.