# Antibacterial activity and physicochemical properties of light-curable fluoride varnishes containing strontium phosphate-based glass

## TL;DR

This study shows that adding strontium phosphate-based glass to light-curable fluoride varnishes improves their antibacterial properties without affecting their physical qualities.

## Contribution

The novel contribution is demonstrating that Sr-PBG can enhance antibacterial activity in LCFVs while maintaining their physicochemical properties.

## Key findings

- LCFVs with Sr-PBG significantly reduced S. mutans CFU compared to the control.
- Incorporating Sr-PBG did not compromise the degree of conversion or film thickness.
- Ion release of Sr and P increased significantly with Sr-PBG addition.

## Abstract

Light-curable fluoride varnishes (LCFVs) have demonstrated enhanced long-term protection of the enamel compared to conventional fluoride varnishes. Strontium-containing phosphate-based glass (Sr-PBG) exhibits antibacterial activity and promotes remineralization through sustained release of calcium, phosphate, and strontium ions. This study aimed to evaluate the antibacterial efficacy and physicochemical properties of LCFVs containing various concentrations of Sr-PBG.

Experimental LCFVs were formulated by incorporating Sr-PBG powder at concentrations of 0 (control), 1.0, 5.0, and 10.0 wt%. Antibacterial effects were assessed by colony-forming units (CFU) of Streptococcus mutans (S. mutans) after 24 and 48 h of incubation, and bacterial adhesion was examined by scanning electron microscopy (SEM). The physicochemical properties, including the degree of conversion, film thickness, contact angle, SEM, and ion release, were evaluated. Data were analyzed using one-way analysis of variance and Tukey’s post-hoc tests (α = 0.05).

All Sr-PBG groups exhibited significantly reduced S. mutans CFU compared to the control (p < 0.05), with antibacterial effects enhanced by longer incubation. Sr-PBG incorporation did not significantly alter the degree of conversion or film thickness (p > 0.05). The contact angle significantly decreased only for 5.0 wt% Sr-PBG (p < 0.05). SEM analysis showed slight particle agglomeration at higher Sr-PBG concentrations, whereas the ion release of Sr and P significantly increased (p < 0.05).

Incorporating ≥ 1.0 wt% Sr-PBG into LCFVs significantly enhanced antibacterial activity against S. mutans without compromising physicochemical properties.

Sr-PBG-containing LCFVs may offer improved clinical efficacy for caries prevention compared with conventional fluoride varnishes, providing enhanced antibacterial performance and promoting an environment favorable for remineralization.