Background The potential contribution of denture-related sores to oral carcinogenesis still fuels controversies. This study assessed the association between recurrent denture-related sores and squamous cell carcinoma in anatomic sites of the mouth that are specifically at risk of sores by ill-fitting dentures.

Methods We conducted a hospital-based case-control study comprising 71 histologically-confirmed cases of squamous cell carcinoma in anatomic sites of the mouth that were specifically at risk of developing sores due to ill-fitting dentures, who were attended at two hospitals in São Paulo, Brazil; and 240 controls without cancer, recruited from outpatient units of the same hospitals. Associations were assessed by multivariate logistic regression conditioned on socio-demographic (family income) and behavioural characteristics (tobacco smoking, alcohol drinking and dietary patterns).

Results The association between ill-fitting dentures and mouth cancer was statistically significant in the multivariate model, which adjustment for socio-demographic and behavioural characteristics: OR=3.98 (95% CI 1.06 to 14.96). The specific assessment of association between tumours in the lower jaw and sores by mandibular dentures confirmed this result (OR=6.39; 95% CI 1.49 to 29.52).

Conclusions These results reinforce the hypothesis that an appropriate application and monitoring of dental prosthesis represent a non-negligible scope for cancer prevention.