Fluoride Reactivity of Silver Diamine Fluoride Solution With Enamel/Dentine

Objectives: Silver diamine fluoride (SDF) solution has been used to control and arrest dentine caries lesions, but due to its alkaline pH, the reactivity of fluoride present in this vehicle may be impaired. In this study, the reactivity of silver diamine fluoride with sound enamel and dentine regarding loosely and firmly-bound fluoride formed was determined.
Methods: Enamel and dentine blocks were divided in 3 treatment/groups (n= 10): distilled water (negative control), silver diamine fluoride (Cariostop 30%, experimental group), and acidulated phosphate fluoride (positive control). The blocks were isolated with wax leaving only enamel or dentine surfaces exposed. The fluoridated products were applied on each block for 1 min. For determination of loosely-bound fluoride, blocks were individually immersed in 1.0M KOH (1.0mL per block) for 24hrs and the alkaline extract was buffered with TISAB II containing 1.0M HCl. The concentration of firmly-bound fluoride was subsequently estimated after etching acid (0.75mL of 0.5M HCl for 30 sec). The acid extract was buffered with TISAB II containing 0.5M NaOH. Fluoride in both extracts was determined with an ion-selective electrode and expressed as µgF/cm2. Data were transformed to log10 and analyzed by one-way ANOVA and Tukey test (α=5%).
Results: SDF formed lower (p<0.05) loosely bound fluoride concentrations (mean±SD, µgF/cm2; n=10) in enamel (1.6±1.0) and dentine (15.2±7.8) than APF (8.0±5.1 and 51.7±17.7, enamel and dentine, respectively). In terms of firmly-bound fluoride concentrations, the treatments SDF and AFP differed statistically only for dentine (SDF=1.14±0.44 and APF=3.52±2.86). Loosely and firmly-bound fluoride of all treatment groups differed from the control for enamel and dentine.
Conclusions: The results suggest that the fluoride reactivity of acidulated phosphate fluoride is higher when compared to silver diamine fluoride.
Conducted during the discipline In Vitro Models in Cariology, Piracicaba Dental School, UNICAMP.