Dentition, oral hygiene, and risk of oral cancer: a case-control study in Beijing, People's Republic of China.

A case-control study of oral cancer was conducted in Beijing, People's Republic of China. The study was hospital-based and controls were hospital in-patients matched to the cases by age and gender. A total of 404 case/control pairs were interviewed. This paper provides data regarding oral conditions as risk factors for oral cancer, with every patient having an intact mouth examined (pre-operation among cases) using a standard examination completed by trained oral physicians. After adjustment for tobacco smoking and alcohol consumption, poor dentition--as reflected by missing teeth--emerged as a strong risk factor for oral cancer: the odds ratio (OR) for those who had lost 15-32 teeth compared to those who had lost none was 5.3 for men and 7.3 for women and the trend was significant (P less than 0.01) in both genders. Those who reported that they did not brush their teeth also had an elevated risk (OR = 6.9 for men, 2.5 for women). Compared to those who had no oral mucosal lesions on examination (OR = 1.0), persons with leukoplakia and lichen planus also showed an elevated risk of oral cancer among men and women. Denture wearing per se did not increase oral cancer risk (OR = 1.0 for men, 1.3 for women) although wearing metal dentures augmented risk (OR = 5.5 for men). These findings indicate that oral hygiene and several oral conditions are risk factors for oral cancer, independently of the known risks associated with smoking and drinking.