It is also generally accepted that periodontal disease is a far more common cause of tooth mobility and pathological tooth migration than any influence of bruxism, although bruxism may much less commonly be involved in both. Causes
The muscles of mastication (the temporalis, masseter, medial and lateral pterygoid muscles) are paired on either side and work together to move the mandible, which hinges and slides around its dual articulation with the skull at the temporomandibular joints. Some of the muscles work to elevate the mandible (close the mouth), and others also are involved in lateral (side to side), protrusive or retractive movements. Mastication (chewing) is a complex neuromuscular activity that can be controlled either by subconscious processes or by conscious processes. In individuals without bruxism or other parafunctional activities, during wakefulness the jaw is generally at rest and the teeth are not in contact, except while speaking, swallowing or chewing. It is estimated that the teeth are in contact for less than 20 minutes per day, mostly during chewing and swallowing. Normally during sleep, the voluntary muscles are inactive due to physiologic motor paralysis, and the jaw is usually open.Some bruxism activity is rhythmic with bite force pulses of tenths of a second (like chewing), and some have longer bite force pulses of 1 to 30 seconds (clenching). Some individuals clench without significant lateral movements. Bruxism can also be regarded as a disorder of repetitive, unconscious contraction of muscles.
Retinal dysplasia in other animals
Cats - Retinal dysplasia occurs in utero or in newborns infected with feline leukemia virus or feline panleukopenia, which cause necrosis and disorganization of the retina. It appears as folds and rosettes. Cattle - Retinal dysplasia occurs in utero through infection with bovine viral diarrhea. It is also inherited in Shorthorns and Herefords. Both forms often cause retinal detachment. Sheep - Retinal dysplasia occurs by in utero infection with bluetongue disease. Horses - Retinal dysplasia is bilateral, not inherited, and appears as multifocal or geographic disease. It is usually accompanied by other eye problems. Chickens

See also
Progressive retinal atrophy


== References ==