A Randomized Controlled Trial of Silver Diamine Fluoride Application Time

Clinicians have recommended, with no scientific evidence, increasing the application times of 38% silver diamine fluoride (SDF) to foster caries arrest. The current study determined the rate of carious lesion activity in response to topical 38% SDF with increasing treatment application time. A 6-mo, stratified-randomized, double-blind, active-controlled, parallel-group trial compared 9 treatment arms. The primary outcome was carious lesion activity at the tooth-surface level 6 mo after initial treatment. Participants included 665 children aged 3 to 4 y with 2,106 carious teeth (234 teeth/group) with 3,024 active carious tooth surfaces. The carious teeth were block randomized into 9 groups with SDF application times of 3, 5, 10, 15, 30, 45, 60, 120, and 180 s. The dose (SDF application time) and response (proportion of active carious tooth surfaces becoming arrested) were modeled using multiple dose-response models. At the 6-mo examination, 642 children with 2,038 SDF-treated carious teeth and 2,939 SDF-treated carious tooth surfaces were evaluated. The estimated proportion of inactive (arrested) lesions (%) increased over time from 75% at 4 s, to 80% at 16 s, and 84% at 60 s. Among the multiple dose-response models, the Emax model provided the best fit. The estimated rate of the proportion of arrested lesions (%s^-1) reduced over time from 0.1%s^-1 at 30 s to 0.05%s^-1 at 43 s. An estimated 16-s application time was required to arrest 80% of caries lesions. The proportion of arrested lesions was associated with lesion-surface type (single/multiple) and tooth location (anterior/posterior). A 16-s application time was estimated to arrest 88% of single tooth-surface lesions in anterior teeth, compared with 66% of multiple tooth-surface lesions in posterior teeth. In conclusion, the trial found an increase in the proportion of arrested lesions with increasing SDF application time, although the rate of the proportion of arrested lesions decreased over application time. (ClinicalTrials.gov NCT04655430).