Objective: To evaluate the effectiveness of professionally applied fluoride varnish on the incidence of dental caries amongst older adults resident in LTCFs in Northern Ireland. Background:The oral health status of older adults within Long-Term Care Facilities (LTCFs) is significantly worse than their community living peers. Whilst evidence suggests an important role for fluoride varnish in preventing caries in this population, very few studies have evaluated this intervention. Materials and Methods: A quality improvement project was undertaken with dentate residents (n = 190) in nine LTCFs who had fluoride varnish applied by Dental Care Professionals on two separate occasions during a 12-month period (intervention group). Nine LTCFs were chosen as matched controls (control group) with comparable numbers of residents of similar medical status (n = 217). For the intervention group, oral hygiene training was also provided for the care home staff. Results: A total of 407 patients (n = 271 female) were included in the analyses (mean age [SD]: 84.1 [6.6] years). After 12 months, the intervention group recorded a significant reduction in mean number of carious teeth (mean [95% CI]: −0.85 [−1.12, −0.58]; P < .001). Patients in the control group had significant increases in the mean number of carious teeth (mean [95%