Is it feasible to conduct a randomised controlled trial of silver diamine fluoride compared to usual care for the management of caries in children’s primary teeth in UK primary dental care? A randomised feasibility study

Dental caries in primary teeth is common for young children in the United Kingdom. Evidence suggests this is not routinely treated in keeping with recommended guidance. Silver diamine fluoride offers an alternative approach however it is unknown whether it is more clinically effective than usual care in NHS primary dental service. Clinical trials in primary dental care have myriad challenges. The aim of this study was to establish whether conducting a randomised controlled trial to compare silver diamine fluoride to usual care for the treatment of caries in children’s primary teeth is feasible. The setting was eight primary dental care sites in Yorkshire and the East Midlands. Children aged 1–8 years old with caries in a primary tooth were randomised in a 1:1 allocation ratio to receive usual care or silver diamine fluoride and followed up for 12 months. Quantitative data were collected at recall and treatment visits pertaining to the feasibility of conducting a definitive trial. This included the ability to recruit, randomise and retain participants and the appropriate outcome measures. Adherence to research processes was also recorded. Qualitative interviews were conducted with children, parents and dental professionals to explore the acceptability of the research processes and intervention. Quantitative data were analysed through descriptive statistics, qualitative data were analysed using thematic analysis. Eight sites recruited 54 children in total. The recruitment rate from those eligible was 94%, however the recruitment period was slow and the target was not met. The majority of children were retained (74%), but there was intermittent missing data owing to missed clinical appointments. For 11 patients there was deviation from the allocated treatment, with a tendency for more children to receive silver diamine fluoride than allocated owing to lack of co-operation with usual care. There was tension between research aims and equipoise, and clinician and family treatment preferences. Candidate outcome measures were well completed, except for caries progression. Although silver diamine fluoride appeared to be potentially beneficial for use with this cohort of patients in primary care, further work is needed to inform the design of a definitive trial. Registration is at Clinaltrials.gov (NCT06092151, 23/10/2023).