Zirconium particles in toothpaste: a novel approach to whitening and its impact on enamel wear

Abrasive agents in toothpaste play a crucial role in plaque removal and stain reduction; however, excessive abrasivity may compromise enamel integrity. Zirconium oxide has recently been proposed as a polishing additive, but its optimal concentration remains unclear. This in vitro study aimed to identify the optimal concentration of zirconium oxide particles in toothpaste for effective cleaning through abrasion of natural dental tissues. The study evaluated enamel substance loss (wear) and surface alteration (roughness) across different zirconium oxide concentrations, highlighting both the advantages and potential risks associated with their use in dental care.

Fifty caries-free third molars with intact crowns were randomly allocated into five groups (n = 10). Four groups were brushed with toothpaste containing zirconium oxide particles at concentrations of 0.5%, 1%, 2%, and 5%, while the control group was brushed with distilled water. Tooth wear and surface roughness were measured before and after brushing using profilometry and intraoral scanning. Statistical analysis included the paired t-test, Wilcoxon matched-pairs signed-rank test, Kruskal-Wallis test, and Dunn's multiple comparisons test.

All zirconium oxide concentrations caused significant tooth wear. Wear analysis revealed significant differences between the 0.5% and 5% groups (p < 0.001) and between the 0.5% and 2% groups (p < 0.05), with no other significant intergroup differences. The 5% concentration produced the greatest increase in surface roughness, with an average rise of 91% (p = 0.002). Conversely, the 0.5% concentration resulted in a significant reduction in roughness (p = 0.002). No significant changes were observed for the 1% (p = 0.375) or 2% (p = 0.105) concentrations.

Toothpaste containing 5% zirconium oxide particles markedly increases enamel wear and surface roughness, whereas lower concentrations (0.5-2%) provide a polishing effect with minimal damage. Optimizing the abrasive properties of toothpaste is crucial to achieve effective cleaning without compromising enamel integrity. Further research is warranted to establish the long-term effects of zirconium oxide-based formulations.