Cross-sectional survey and analysis of factors associated with adult dental caries in Ngari Prefecture, Tibet, China (2021–2022)

Ngari Prefecture, Tibet, a typical cold and hypoxic region with an average altitude over 4,500 m, lacks sufficient oral health survey data on local dental caries. This study estimated the prevalence of dental caries and explored its associations with sociodemographic characteristics and oral health behaviors. Adults aged 25–74 years were recruited using a multistage design with quota sampling at the final stage. Decayed, missing, and filled tooth (DMFT), decayed and filled root (DF-Root), oral-health awareness, and behaviors were assessed. Statistical analyses included independent-samples t tests, chi-square tests, multivariable logistic regression, and a modified Poisson sensitivity analysis with robust variance estimation. A total of 607 participants were divided into five age groups:25–34, 35–44, 45–54, 55–64 and 65–74 years. The mean DMFT(SD) of each group was 4.00(1.98), 7.50(3.38), 8.59(4.59), 11.63(4.77), and 17.40(5.61). Coronal caries restoration rates were 36.59%, 18.85%, 15.83%, 9.84%, and 10.00%, with Crown Caries Filling Ratio (CCFR) of 26.64%, 7.11%, 5.68%, 2.73%, and 2.15%. The mean DF-Root (SD) was 0.31 (0.62), 0.76 (1.38), 1.15 (1.50), 1.98 (2.32), and 2.63 (2.65). Multivariable logistic regression showed that female gender (aOR = 1.86, 95% CI:1.11–3.11), rural residency (aOR = 2.19, 95% CI:1.29–3.70), 45–54,55–64,65–74 year age groups (aOR = 5.04, 95% CI:2.17–11.68; aOR = 12.30, 95% CI:5.60-27.01; aOR = 73.91, 95% CI: 30.97-176.38; modified Poisson sensitivity analysis: aPR = 12.62, 95% CI: 6.76–23.55) and valuing oral health and dental aesthetics (aOR = 2.93, 95% CI:1.23–6.99) were positively associated with coronal caries, while annual household income ≥CNY30,000 (aOR = 0.25, 95% CI:0.10–0.67) showed a negative association with this outcome. For root caries, female gender (aOR = 1.67,95% CI:1.13–2.48), rural residency (aOR = 2.99,95% CI:1.99–4.50), and 45–54,55–64, 65-74y age groups (aOR = 2.15, 95% CI:1.06–4.34; aOR = 3.24, 95% CI:1.59–6.60; aOR = 3.69, 95% CI:1.73–7.89) were positively associated with root caries. Factors inversely associated with root caries included primary school education (aOR = 0.35,95% CI:0.19–0.63), Dental checkup frequency above 1 year (aOR = 0.62, 95% CI:0.40–0.98),annual household income of CNY10,000-<30,000 (aOR = 0.37,95% CI:0.24–0.59),and ≥CNY30,000 (aOR = 0.39,95% CI:0.21–0.72). Adults in Ngari Prefecture have a high burden of severe dental caries. Coronal caries is correlated with region, gender, age, oral health awareness, and income, while root caries is associated with region, gender, age, educational attainment, and income. These findings may inform the reduction of caries prevalence in Ngari Prefecture.