Purpose <p>To investigate the association between occlusal support and the frequency of self-reported witnessed apnea during sleep in a community-based population, given limited evidence regarding role of oral conditions in sleep-disordered breathing, and to examine sex-specific differences in this association.</p> Methods <p>This cross-sectional study included 4,847 community-dwelling Japanese adults aged 40–76 years. Witnessed apnea was assessed using a self-administered questionnaire and categorized as none, sometimes, or almost every day. Occlusal support was defined by the ability to bite with posterior teeth bilaterally. Multivariable ordinal logistic regression analyses were performed to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs). Interaction between sex and occlusal support was also examined by including an interaction term in the multivariable model, followed by sex-stratified analyses.</p> Results <p>Loss of occlusal support was observed in 4.1% of participants, and 15.8% reported witnessed apnea. In overall multivariable analysis, loss of occlusal support was not significantly associated with witnessed apnea. However, significant interaction between sex and occlusal support was identified. In sex-stratified analyses, loss of occlusal support was significantly associated with a higher frequency of witnessed apnea among women (adjusted OR, 2.11; 95% CI, 1.12–3.97; <i>p</i> = 0.021), whereas no significant association was observed in men.</p> Conclusion <p>Loss of occlusal support was associated with a higher frequency of witnessed apnea in women but not in men, suggesting a sex-specific relationship. These findings indicate that oral conditions may contribute to the risk of sleep-disordered breathing and highlight the importance of considering sex differences in risk assessment.</p>