Abstract
BACKGROUND: Temporomandibular disorders (TMD) are common among undergraduate dental students and have been associated with sleep disturbances. Dental students may be particularly vulnerable due to the academic and clinical demands of their education. This study aimed to evaluate the association between TMD-related clinical signs and sleep quality among undergraduate dental students. METHODS: This cross-sectional study included 210 undergraduate dental students classified as TMD-positive (≥ 1 clinical sign: TMJ pain, clicking, or functional limitation, n = 115) or TMD-negative (no clinical signs, n = 95). Students with a history of temporomandibular joint treatment, current orthodontic treatment, diagnosed psychiatric disorders, chronic systemic diseases, or regular use of medications affecting sleep were excluded. TMD status was determined based on clinical findings, including joint pain, clicking, and functional limitation. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Total PSQI scores were analyzed as both continuous and categorical variables (cut-off > 5). Data were analysed using non-parametric tests and Chi-Square/Fisher's Exact tests and associations with poor sleep quality (PSQI > 5) were examined using modified Poisson regression with robust standard errors to estimate aPRs (95% CIs) including a TMD×sex interaction (two-sided α = 0.05). RESULTS: Poor sleep quality (PSQI > 5) was more frequent among students with TMD than those without TMD (100% and 93.68%, respectively; p = 0.008) and in females than in males (100% and 92.86%, respectively; p = 0.004). PSQI scores increased across academic years and proportion of students classified as poor sleepers differed by year (p = 0.0008). In modified Poisson regression adjusted for sex, academic year and age, TMD was independently associated with poor sleep (aPR = 1.04, 95% CI 1.006-1.075; p = 0.019). A significant TMD×sex interaction indicated effect modification by sex; the association was evident among males (male-stratified aPR = 1.11, 95% CI 1.02-1.21; p = 0.015), while estimation within females was not feasible due to universal poor sleep. CONCLUSIONS: TMD-related clinical signs were associated with poorer sleep quality among dental students. These findings indicated that sleep disturbances and TMD-related symptoms frequently co-occur in this population. Given the cross-sectional design, causal inferences cannot be drawn, and longitudinal studies are warranted.