# Evaluation of Tooth Color Changes at Different Concentrations of Zirconia Toothpaste: A Pilot In Vitro Study

## TL;DR

This study tests how different zirconia concentrations in toothpaste affect teeth whitening and enamel surface roughness in a lab setting.

## Contribution

The study introduces zirconia as a novel whitening agent and evaluates its effectiveness at various concentrations.

## Key findings

- All zirconia concentrations caused detectable tooth color changes, with some exceeding clinical acceptability.
- Zirconia at 1–2% provided optimal whitening without harming enamel, while 5% increased surface roughness.
- Lower concentrations (0.5%) showed less whitening and mixed effects on surface roughness.

## Abstract

Background: The demand for natural, minimally invasive teeth whitening solutions has led to interest in products using natural abrasives. Zirconium, known for its abrasive properties, has been suggested as a potential whitening agent, but its efficacy compared to traditional methods is underexplored. This study aims to address this gap by evaluating zirconium powder at various concentrations as a novel approach to tooth whitening while preserving the enamel surface. Materials and Methods: Forty extracted mandibular teeth (twenty anterior, twenty posterior) were allocated into four groups and brushed for 2 min with zirconia toothpaste at one of the four concentrations. Color parameters (CIE Lab*), ΔE, and WID were measured before and after brushing using a spectrophotometer; surface roughness was assessed with a profilometer. Data were analyzed with paired tests and ANOVA/Kruskal–Wallis (p < 0.05). Results: All groups showed detectable color change (ΔE > 1.2); several exceeded clinical acceptability (ΔE ≥ 2.7). WID increased in all groups, with the largest gains at 2% zirconia for posterior teeth (+31.58) and 1% or 5% for anterior teeth (+21.07, +21.19). Surface roughness decreased significantly at 0.5% (p ≈ 0.002) and increased at 5% (p ≈ 0.002); no significant change occurred at 1% and 2%. Conclusions: Zirconia toothpaste at 1–2% offers the best balance between whitening efficacy and enamel preservation, while 5% increases roughness and 0.5% produces smaller whitening results.