[Clinical investigation of oral submucous fibrosis].

In the Xiang Tan city of the Hunan Province 3015 adult of betel were examined intra-orally. Twenty-nine cases of oral submucous fibrosis were found. Other five cases were collected from out-patient department of the hospital. There were thirty-four cases altogether. In the control group, no case was found. The patients of submucous fibrosis were not chewers of tobacco. Four cases of leukoplakia has been found in them. There was not, however, a single case of oral cancer. The clinical investigation supports that chewing of betel is an important etiological factor of oral submucous fibrosis.