Rabbits, Guinea pigs and Rodents have teeth that grow continuously. Teeth need to be worn down by chewing, as they grow all the time (in rabbits over 50mm / year about 2mm a week). Many animals need extra things to chew on, particularly if they are not on a natural diet of grass and hay to stop teeth over growth.
Commercial diets need little effort or time for chewing, due to food processing, so teeth are not worn down and this can cause severe problems.
It is important to remember it is not just the incisor teeth at the front but also the molars or check teeth that also overgrow. Often an x-ray is needed to see which teeth are bad.
If your pet has overgrown the best way to treat this problem is for your pet to have an anaesthetic and a special low speed dental hand piece can be used to restore occlusal surface of both incisors and check teeth to normal level and angle. This may need to be repeated every 6 weeks till they can grind well again.
Clipping or rasping of incisors teeth is not advised because this may cause tooth fracture and damage to periodontal and per apical tissue, which is painful and can lead to life long problems.
If overgrowth has been left too long before treatment , the curvature of the teeth will change, and may change the angle of the teeth in their sockets. Bad teeth can cause eye problems and abscesses. Often in severe cases, it is best to remove the tooth (or teeth) including the root. This is difficult and expensive. There is a high risk of fracture of bone around the tooth and risk of infection in bone (osteomyelitis). Often multiple surgical procedures are required and even with aggressive therapy, treatment may not be successful. Sometimes months of treatment are needed. It is important you understand how severe this problem is and consider all options including euthanasia in discussion with your vet about care for your pet.
After any dental work, it takes several weeks for the jaw muscles to get back their normal contraction / grinding and chewing pattern. Supportive feeding will be needed initially. As soon as possible start feeding a natural diet to promote normal chewing. Fresh growing grass in best, but freshly cut long grass and other natural vegetation (not lawn clippings) and hay are acceptable.
Preventing dental problems by feeding a natural diet with large volumes of abrasive low-energy food such as grass and hay is the best care you can give your pet.