In vitro evaluation of the effects of various remineralization agents on root caries

Although various additions are made to fluoride varnishes, there is limited research on their effects on the root caries.

This study compared the effects of different fluoride varnishes on artificial root caries lesions and biofilm formation.

Bovine root dentin specimens were prepared and demineralized. Specimens were randomly allocated to six groups (n=23/group): (1) Untreated control; (2) Sodium Fluoride (NaF); (3) NaF+ Casein Phosphopeptide-stabilized Amorphous Calcium Phosphate complexes (CPP-ACP); (4) NaF+ Tricalcium Phosphate (TCP); (5) NaF+ Xylitol-coated Calcium and Phosphate (CXP); and (6) Silver Diamine Fluoride/Potassium Iodide (SDF/KI). Specimens (n=15) for spectral analysis were subjected to pH cycling. Before and after pH cycling, FTIR-ATR and laser fluorescence (LF) were used to detect changes in organic/inorganic content. S. mutans and L. casei dual-species biofilm were performed on artificial caries lesions treated with remineralization agents (n=8). Bacterial biofilm formation was evaluated with CLSM and SEM.

According to the laser fluorescence results, SDF/KI showed maximum remineralization values. All treatments reduced LF values compared with control group. FTIR-ATR showed SDF/KI-specific post-cycling bands (weak C = O at ~ 1735-1740 cm⁻¹ and a subtle ~ 1090-1095 cm⁻¹ shoulder), while phosphate/amide I ratios in NaF, CPP-ACP, TCP, and CXP varnish groups decreased after cycling but tended to remain higher than control, with no differences among varnishes (p > 0.05); ratios were not calculated for SDF/KI. CLSM analysis showed that all varnishes are effective on total and viable biomass. However, NaF was the most effective material preventing biofilm formation. The application of varnishes reduced biofilm formation and demineralization of root caries.

Within the limits of this study, fluoride varnishes were found to be beneficial in preventing further demineralization of root tissues.