Objective: The trial aimed to study the additive effect of domiciliary professional dental cleaning on root caries lesions (RCLs), oral hygiene outcomes and oral health-related quality of life (OHRQoL) in care-dependent older adults with in-home care that use high fluoride toothpaste, compared with oral care as usual for a year. Basic research design: Parallel-group evaluator-blinded randomized controlled trial. Clinical settings: Participants own home in Sweden. Participants: 194 care-dependent with in-home care aged ≥65 years and ≥1 natural tooth were randomized (1:1) in blocks by computer-generated sequence. 149 were available at baseline (intervention (I) = 80, control (C) = 69). All were provided with toothbrushes and high-fluoride toothpaste (5,000 ppm F) for daily use. Intervention: Domiciliary professional dental cleaning and oral hygiene instructions by dental assistant, every third month. Main outcomes: The primary outcome was RCLs progression. Secondary outcomes were gingival bleeding, oral hygiene, hyposalivation and OHRQoL, registered at baseline and after 1 year by dental hygienists. Results: Due to high attrition (45%), 82 individuals remained (I = 50, C = 32) after 1 year resulting in an underpowered study. The number of subjects assessed with RCLs progression was 11 (22.0%) in I group and 9 (28.1%) in C. With the use of per protocol analysis, no significant differences between groups were seen for any of the outcomes. Conclusions: Domiciliary professional dental cleaning to care-dependent older adults does not seem to have any additive preventing effect on RCLs to daily toothbrushing with high-fluoride toothpaste. This suggests that focus be maintaining good daily oral health routines rather than home-care visits to maintain oral health.