Oral Health, Polypharmacy and Nutritional Status in Institutionalized Dementia Patients: A Multicenter Cross-Sectional Study

Background: As the population ages, dementia poses a critical public health challenge. This study examined the oral health and nutritional status of institutionalized Portuguese adults with dementia, exploring their interrelated predictors. Methods: This multicenter, cross-sectional study assessed institutionalized patients using the Decayed, Missing, and Filled Teeth (DMFT) index, posterior functional units (PFUs), plaque (PI) and gingival (GI) indices, the Short Xerostomia Inventory (SXI-5), and the Mini Nutritional Assessment (MNA). DMFT was modeled using multivariable ordinary least squares (OLS) regression for demographic and clinical predictors and separate negative binomial models for medication-related predictors. Other outcomes were analyzed using outcome-specific multivariable models. Results: The study included 71 participants (mean age: 82.5 ± 6.9 years). A high dental disease burden (mean DMFT score of 24.3 ± 7.5) was observed, independently predicted by advanced age (β = 0.48, p = 0.002) and residence in public long-term care units (LTCUs) (β = 6.65, p = 0.001). Total edentulism affected 28.2% of the sample. Polypharmacy emerged as a significant predictor of tooth loss; each additional medication was associated with an 18% decrease in the likelihood of retaining natural teeth (OR = 0.82, p = 0.008). Higher cognitive decline (GDS) was associated with increased plaque (p = 0.043), and modified-texture diets were associated with lower plaque levels (β = −0.64, p = 0.021). The mean MNA score (16.9 ± 3.8) indicated a high risk of malnutrition, with a trend toward lower gingival inflammation with better nutritional status (p = 0.061). Conclusions: Institutionalized dementia patients face severe oral and nutritional risks associated with age, polypharmacy and institutional environment. This emphasizes the need for multidisciplinary protocols and caregiver training.