Functional dependence, cognitive function, and nutritional status are independently associated with oral health in care-dependent older residents in integrated medical and nursing care institutions

This study examined the oral health of older inpatients with disabilities and its links to functional dependence, cognitive function, and nutritional status in medical-care institutions. This study utilized a cross-sectional design between June and December 2025 and recruited a convenience sample of 150 older inpatients with disabilities from two comparable medical-care institutions in terms of care level and patient characteristics. Data collection involved oral examinations, which included the Decayed, Missing, and Filled Teeth (DMFT) index, Gingival Index (GI), and assessment of prosthetic status (classified as ideal or non-ideal). Additionally, evaluations were conducted using the Barthel Index, Mini-Mental State Examination (MMSE) score, Mini Nutritional Assessment Short-Form (MNA-SF) score, Charlson Comorbidity Index (CCI), and medication count. Data analysis was carried out using multiple linear regression for continuous outcomes (DMFT index and GI) and logistic regression for the binary outcome (prosthetic status). The study population demonstrated significant systemic health challenges, with a mean age of 82.79 ± 8.32 years. Severe functional dependence was observed in 72.7% of participants, cognitive impairment in 68.7%, and a risk of malnutrition in 63.3%. The mean Decayed, Missing, and Filled Teeth (DMFT) index was 25.17 ± 6.55, and 77.3% of participants exhibited non-ideal prosthetic status. The mean Gingival Index (GI) was 1.39 ± 0.73 among 139 participants with natural teeth, as 11 edentulous participants were excluded from GI analyses. Multiple regression analyses identified distinct association patterns: the DMFT index was independently associated with a lower Barthel Index (B = − 0.099, 95% CI − 0.154 to − 0.044, p < 0.001) and a lower MNA-SF score (B = − 0.778, 95% CI − 1.173 to − 0.383, p < 0.001). The GI was independently associated with an increased number of medications (B = 0.109, 95% CI 0.013 to 0.204, p = 0.026) and a lower MNA-SF score (B = − 0.121, 95% CI − 0.168 to − 0.074, p < 0.001). Non-ideal prosthetic status was independently associated with a higher CCI score (OR = 2.762, 95% CI 1.287 to 5.927, p = 0.009), a lower Barthel Index (OR = 0.946, 95% CI 0.908 to 0.987, p = 0.010), and a lower MMSE score (OR = 0.803, 95% CI 0.696 to 0.928, p = 0.003). Older inpatients with disabilities in medical-care institutions exhibit significant oral health challenges. Distinct core health dimensions are associated with dental caries, gingival inflammation, and prosthetic status. Given the cross-sectional design, these associations should not be interpreted as causal. Nevertheless, the observed patterns suggest potential targets for comprehensive oral health strategies that may incorporate nutritional support, functional rehabilitation, medication management, and cognitive care.