Factors associated with poor oral hygiene by intraoral region among residents with disabilities in Thai residential facilities: a cross-sectional secondary analysis

To estimate the prevalence of poor oral hygiene using the Simplified Oral Hygiene Index (OHI-S) overall and by intraoral region and to identify factors associated with poor oral hygiene among residents with disabilities in Thai residential facilities. We conducted a secondary analysis of a facility-based cross-sectional oral health survey conducted in two government-run residential facilities in Thailand. Poor oral hygiene was defined as OHI-S 3.1-6.0 (versus 0–3.0) and evaluated for anterior teeth, upper posterior teeth, lower posterior teeth, and overall (six index teeth). Associations between participant characteristics/behaviors and poor OHI-S were examined using chi-square tests. Multivariable logistic regression models were fitted for each intraoral region and overall OHI-S, including a priori selected predictors based on conceptual relevance to oral hygiene in disability and residential-care settings, availability in the dataset, and model parsimony. The analytical sample included 298 participants. Poor oral hygiene was most prevalent in the upper posterior (63.0%) and lower posterior regions (57.7%); overall poor OHI-S occurred in 55.7%, and poor anterior OHI-S in 37.4%. In adjusted analyses, adults aged 19 to 59 years had higher odds of poor overall OHI-S (adjusted odds ratio aOR 3.19, 95% CI 1.59 to 6.40). Physical disability was associated with poor anterior OHI-S (aOR 3.77, 95% CI 1.32 to 10.73). Brushing fewer than twice daily was associated with poor upper posterior OHI-S (aOR 2.90, 95% CI 1.21 to 6.91), poor lower posterior OHI-S (aOR 2.69, 95% CI 1.20 to 6.05), and poor overall OHI-S (aOR 2.19, 95% CI 1.02 to 4.70). Chewing problems were associated with poor anterior OHI-S (aOR 3.11, 95% CI 1.20 to 8.06). Poor oral hygiene was highly prevalent among residents with disabilities, particularly on posterior teeth. These findings suggest prioritizing daily plaque control support, with targeted attention to adults aged 19–59 years, residents who brush less than twice daily, and those with functional limitations such as chewing difficulties.