A composite oral hygiene score and the risk of oral cancer and its subtypes: a large-scale propensity score-based study

Objective This study aimed to investigate the potential relationship between oral hygiene and the risk of oral cancer and its subtypes after controlling the effects of several confounding factors. Materials and methods A large-scale case-control study was conducted from January 2010 to August 2019, recruiting a total of 1,288 oral cancer cases with newly diagnosed and 4,234 healthy controls. Propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) were utilized to minimize confounding effects. Conditional logistic regression was used to evaluate the effects of oral hygiene indicators on oral cancer. Results A composite oral hygiene score was developed based on five indicators selected based on PSM and IPTW analysis (including tooth loss, dentures wearing, the frequency of tooth brushing, regular dental visits, and recurrent dental ulcer). Participants with a higher score, compared with their lower counterparts, showed a 49% increased risk (the odds ratio (OR) was 1.49 (95% confidence interval (CI): 1.26-1.75). A similar association pattern was found following IPTW analyses (OR = 1.32; 95% CI: 1.22-1.42). Of note, the adverse effects of poor oral hygiene were more evident among the sites of gingival and buccal (PSM analysis: 2.03-fold and 2.68-fold increased risk; IPTW analysis: 1.57-fold and 2.07-fold increased risk, respectively). Additionally, a greater positive association was observed between poor oral hygiene and oral squamous cell carcinoma, compared with other pathological types. Conclusion This study establishes a composite oral hygiene score and provides supportive evidence of poor oral hygiene associated with a higher risk of oral cancer, particularly in the gingival and buccal mucosa sites and in the squamous cell carcinoma. Clinical relevance The data highlights the importance of improving poor oral hygiene habits, which has public health implications for the prevention of oral cancer.