1 Division of Gerodontology and Removable Prosthodontics, University Clinics of Dental Medicine, University of Geneva, Rue Michel Servet 1, Geneva, 1211, Switzerland. Najla.Chebib@Unige.Ch.
2 Division of Gerodontology and Removable Prosthodontics, University Clinics of Dental Medicine, University of Geneva, Rue Michel Servet 1, Geneva, 1211, Switzerland.
3 Software Engineer, Concordia University, Montreal, Canada.
4 Center of Excellence in Precision Medicine and Digital Health, Geriatric Dentistry and Special Patients Care International Program, Department of Physiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.

Background: This RCT aimed to test the impact of an educational intervention, supported by a Personalized Oral Health Instruction Form (POIF), on oral health indices in institutionalized older adults.

Methods: Older adults aged 65 years and above living in a long-term care facility were recruited. Baseline oral health indices were recorded for all participants. Caregivers received training on oral health care in small groups. Custom-made software was used to create a POIF for each participant, which was then implemented alongside verbal instructions and the provision of an oral hygiene kit in the intervention group, whereas in the control group, the participants received verbal instructions and an oral hygiene kit only. After three weeks, a second examination was conducted by the same examiner, who was blinded to participants' group allocation. Plaque index (PI), denture cleanliness (DCI), and tongue coating (TCI) were recorded at baseline and after intervention. Oral health-related quality of life (OHRQoL), assessed at baseline and after intervention using the Geriatric Oral Health Assessment Index (GOHAI). Wilcoxon signed rank tests were conducted with the level of significance set at P<0.05.

Results: A total of 46 patients (mean age: 85.5 ± 7.7 years) were included. Plaque index (PI) significantly decreased in both groups from baseline to postintervention (p < 0.001), with a significantly lower median score in the intervention group (31.6%, IQR=51.1) than in the control group (53.9%, IQR=51.1; P = 0.023). DCI improved significantly within the intervention group (Wilcoxon P = 0.046), with a greater proportion of patients showing no visible plaque after the intervention than at baseline (66.7% vs. 33.3%). TCI did not change significantly over time in either group (n.s.). A combined hygiene outcome based on the PI and DCI showed significantly better plaque control in the intervention group (P =0.006). GOHAI total score increased from 50 (IQR=9) to 54 (IQR= 4). This improvement was statistically significant within the intervention group (P = 0.006), whereas it was not significant between groups at the final assessment.

Conclusions: The findings confirm that POIFs using tailored, visually supported, printed oral health guidance improve oral health outcomes in institutionalized older adults.

Trial registration: This study was approved by the ethics committee of the canton of Geneva (CCER 2022--00086) and registered on the Swiss national registry for clinical trials (SNCTP000004829) and was retrospectively registered on clinical trials with the registration number NCT07063927 on 2025-07-02.