Natural Tooth Count and Sleep Quality in Older Adults: The Mediating Effect of Temporomandibular Joint Pain

PURPOSE: The study aimed to explore the relationship between tooth count and sleep quality and duration in the elderly, investigating the potential mediating role of temporomandibular joint (TMJ) pain in this relationship. METHODS: Using data from the China Health and Longevity Longitudinal Survey (CLHLS), a cohort analysis was conducted on 5941 older Chinese adults. Multivariate linear regression and mediation analysis were applied to assess the associations, adjusting for sociodemographic factors, health behaviours, and comorbidities. RESULTS: The participants had a mean natural tooth count of 10.1 (SD = 10.4), a mean sleep quality score of 2.38 (SD = 0.93; lower scores indicate better quality), and a TMJ pain prevalence of 6.93%. Linear regression showed that more natural teeth were associated with better sleep quality (coefficient = -0.0036, P = .012), meaning each additional tooth correlated with a small improvement in sleep quality. TMJ pain was linked to poorer sleep quality (coefficient = 0.2175, P < .001), indicating worse sleep in those with TMJ pain. Mediation analysis revealed that TMJ pain partially mediated the relationship: the indirect effect (average causal mediation effect [ACME] = 0.0004, 95% CI: 0.0002 to 0.0005, P < .001) accounted for 11.5% of the total effect, while the direct effect of tooth count on sleep quality remained significant (ADE = -0.0039, P = .006). CONCLUSION: More natural teeth are associated with better sleep quality in older adults, and TMJ pain partially mediates this relationship. CLINICAL RELEVANCE: These findings highlight the importance of oral health (tooth retention and TMJ pain management) in improving sleep quality among older adults, providing new insights for clinical intervention in sleep disorders.