# Evaluation of cytotoxicity and bleaching efficacy of gels with calcium polyphosphate and violet LED

## TL;DR

This study evaluates the effectiveness and safety of a tooth whitening gel combining hydrogen peroxide, calcium polyphosphate, and violet LED light.

## Contribution

The novel contribution is demonstrating that adding calcium polyphosphate and violet LED to low-concentration hydrogen peroxide improves cytocompatibility and reduces oxidative stress without affecting whitening efficacy.

## Key findings

- Cell viability was highest in the HP10%_CaPP+L group (72.17%) and lowest in the HP10% group (54.48%).
- Oxidative stress was significantly lower in HP10%_CaPP+L compared to HP10%+L.
- Calcium polyphosphate reduced hydrogen peroxide diffusion and did not impact bleaching efficacy.

## Abstract

To evaluate the whitening effect and cytotoxicity of low-concentration hydrogen peroxide (HP 10%) combined with calcium polyphosphate (CaPP) submicroparticles, irradiated or not with a violet LED (LEDv). Bovine tooth samples were divided into 6 groups (n=6): Control Group (no treatment); LED; Manipulated 10% HP (HP10%); Manipulated 10% HP + CaPP 1.5% w/t (HP10%_CaPP); Manipulated 10% HP + LED (HP10%+L); and Manipulated 10% HP + CaPP 1.5% w/t + LED (HP 10%_CaPP+L). The treatments were applied to the enamel of disks mounted in artificial pulp chambers. The whitening effect (ΔE00 and ΔWID) was measured, and the extracts were applied to MDPC-23 cells, assessing cell viability, oxidative stress, and HP diffusion. The data were analyzed using generalized linear models, and the Kruskal-Wallis/Dunn tests were applied for WID (a=5%). Cell viability was significantly reduced in all HP groups compared to controls (Control: 100.15 ± 1.71%; LED: 99.89 ± 2.43%), with the highest viability in HP10%_CaPP+L (72.17 ± 4.14%) and the lowest in HP10% (54.48 ± 1.72%). Oxidative stress was lowest in HP10%_CaPP+L (2.91 ± 0.17) and highest in HP10%+L (3.77 ± 0.15). HP diffusion was markedly reduced with CaPP (HP10%_CaPP+L: 2.93 ± 0.18 vs. HP10%: 4.24 ± 0.10). In terms of color analysis, the addition of CaPP did not alter the bleaching efficacy. The addition of CaPP to hydrogen peroxide, combined with violet LED, demonstrated effective bleaching action, positive indicators of cytocompatibility, increased cell viability, and reduced oxidative stress