Oral health status and associated factors among rural older adults in China using a 3D intraoral scanner: a population-based cross-sectional study in four provinces.

objectiveThis study aimed to validate intraoral scanning (IOS) for oral health surveys, describe oral health status among rural older adults in China, and analyze associated factors and pathways to provide evidence for targeted interventions.

methodsA cross-sectional survey was conducted in 2024 among 2,179 rural adults aged ≥ 60 from four Chinese provinces using multistage cluster sampling. Data were collected through clinical oral examinations, IOS (dentition status, periodontal status, oral cleanliness, and denture status), and face-to-face questionnaires (general characteristics, oral hygiene behaviors, oral health service utilization, oral health literacy, oral frailty, and oral health-related quality of life). The diagnostic accuracy of the IOS was evaluated using sensitivity, specificity, Cohen's Kappa, and the area under the curve (AUC), with clinical examination as the reference standard. Oral health status was characterized using descriptive analyses. Factors associated with the number of remaining teeth (categorized into three groups: 1-9, 10-19, and ≥ 20) were identified using ordinal logistic regression. Structural equation modeling (SEM), guided by the Wilson and Cleary model, was applied to incorporate variables and examine potential pathways.

resultsThe Runyes intraoral scanner showed sensitivities of 95.24%-99.41%, AUC values of 0.821-0.919, and kappa coefficients of 0.736-0.845, compared with inter-examiner agreement for clinical examination (kappa: 0.84-0.91). The mean number of remaining teeth was 17.46 ± 10.59, and 13.4% of participants were edentulous. The mean DMFT score was 15.98, with dental caries present in 97.0%. Among dentate participants, dental calculus and gingival recession were observed in 99.9% and 97.3%, respectively, and over 95% had poor oral cleanliness. Approximately 50% of participants used dentures. Fewer remaining teeth were associated with older age, smoking, prior dental treatment, recent toothache, lower income, weaker grip strength, non-use of fluoride toothpaste and dental floss, and lower oral health literacy (OHL). SEM showed that oral health skill, including use of interdental cleaning tools, brushing duration, and brushing force, significantly moderated the downstream effects of poor oral health status into adverse oral health-related quality of life outcomes (interaction effects p < 0.05).

conclusion3D IOSs may serve as an efficient tool for oral health surveys. Rural older adults in China experience considerable oral health challenges. Improving OHL through targeted strategies could contribute to better oral health status in this population.