Clinico-statistical observation on TMJ arthrosis in young people under 20 years old was studied. The subjects were 238 patients who visited Department of Oral Surgery, School of Medicine, Nagoya University Hospital during the 13 years (1971-1984).
1. The proportion of young people to hole TMJ arthrosis patients by each year had been increased gradually.
2. On sexual difference, female is 2.4 times more than male. On damaged side, the left side is a little more than the right side.
3. On incidental classification, internal injury is the most usual case (76.1%), the second is external injury (13.0%), and the third is ideopathic (10.9%). In primary clinical symptoms, the sound of TMJ is the most usual one.
As mentioned above, we considered that in young cases of TMJ arthrosis, the sound of TMJ has been generated by dislocation of the disc because of disharmony of TMJ components by internal injury.