Effects of silver diammine fluoride in preventing dental caries in removable partial denture wearers : a randomized double-blind, placebo-controlled study

Abstract

OBJECTIVES: The primary objective of this study was to evaluate the efficacy of silver diammine fluoride (SDF) solution in preventing coronal and root caries over 36 months in people wearing removable partial dentures (RPDs). Secondary objective was to investigate the effect of SDF solution on oral microorganisms (Candida, Lactobacilli, and Streptococcus mutans) over 24 months in people wearing RPDs. METHODS: This study was a randomized, double-blind, placebo-controlled clinical trial. Patients wearing RPDs were randomly assigned to receive a 38% SDF solution or placebo (water) application semi-annually. Assessments of dental conditions (coronal smooth surfaces / root surfaces), oral hygiene (dental plaque accumulation / gingival bleeding), and salivary measurements (flow rate / pH / buffering capacity) were conducted annually by the same calibrated examiner over 36 months. Oral microbiological profiles were explored at the baseline and 24-month follow-up. RESULTS: A total of 194 RPD wearers (mean age=64.8) were recruited at baseline, and 168 (86.6%) completed the 36-month trial. At the 36-month evaluation, the mean numbers of coronal smooth surfaces with new caries were 0.5 and 0.9 in the SDF and placebo groups respectively (P=0.018). The mean numbers of root surfaces with new caries were 0.8 and 1.9 in the SDF and placebo groups respectively (P<0.001). Results of ANCOVA and multi-level logistic analysis showed that SDF application was efficacious in preventing new caries on both coronal smooth surfaces and root surfaces. Factors including patients’ work status, tooth-brushing frequency, snacking frequency, oral hygiene, RPD base material, past caries experience, tooth/surface location and denture contact were significantly associated with dental caries development. At the 24-month evaluation, oral microbiological profiles were explored in 176 (90.7%) patients. Compared to baseline, the prevalence and mean count of lactobacilli in dental plaque (P<0.05), and the mean count of Candida in denture plaque (P=0.009) increased significantly in the placebo group, while in the SDF group the prevalence of Candida in oral rinse decreased significantly (P=0.004). Results of logistic regression showed that SDF application was significantly associated with a lower likelihood of presence of lactobacilli in dental plaque (P=0.007) and presence of Candida in oral rinse (P=0.035) at 24-month follow-up while not significantly associated with the presence of Streptococcus mutans. CONCLUSIONS: Semi-annual application of SDF solution is efficacious in 1) preventing new caries on coronal smooth surfaces and root surfaces of teeth over 36 months and 2) inhibiting the oral colonization of lactobacilli and Candida among RPD wearers over 24 months.