Comparison of Two Bioactive Glass Incorporated Toothpastes for Restoring Mineral Loss After Dental Bleaching with 35% Hydrogen Peroxide and 35% Carbamide Peroxide: An in Vitro Study

Abstract

Dental bleaching may cause alterations in the mineral composition of enamel. This in vitro study aimed to evaluate and compare the effects of NovaMin and BioMin-containing toothpastes on the calcium and phosphorus content of enamel following bleaching with 35% hydrogen peroxide and 35% carbamide peroxide.
Materials and Methods: Forty-eight extracted human maxillary anterior teeth were allocated to two groups according to the bleaching agent used: 35% hydrogen peroxide and 35% carbamide peroxide. Each group was further divided into three subgroups (n = 8): bleaching alone, bleaching followed by NovaMin toothpaste, and bleaching followed by BioMin toothpaste. Enamel mineral deposition was assessed by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Calcium and phosphorus contents were analysed using analysis of variance followed by the Tukey's honestly significant difference (HSD) test. Statistical significance was set at p < 0.05.
Results: Bleaching alone resulted in lower calcium and phosphorus contents compared with the remineralisation groups. Following 35% hydrogen peroxide bleaching, the mean calcium content was 14.51% in the control group, compared with 31.46% and 32.53% following NovaMin and BioMin application, respectively. Corresponding phosphorus values were 7.08%, 15.74%, and 15.51%. Following 35% carbamide peroxide bleaching, mean calcium content was 14.93% in the control group, compared with 29.57% and 29.64% following NovaMin and BioMin application, respectively, while phosphorus content was 7.41%, 15.09%, and 15.85%. Both remineralisation groups showed significantly greater calcium and phosphorus contents than the respective control groups (p < 0.001). However, no significant differences were found between NovaMin and BioMin for either mineral.
Conclusions: Within the limitations inherent to in-vitro studies, it can be concluded that application of remineralising agents produces a significant increase in enamel calcium and phosphate content following bleaching with 35% hydrogen peroxide and 35% carbamide peroxide. No statistically significant difference was detected between NovaMin and BioMin in this remineralising effect; however, given the limited power of these specific comparisons, this finding should not be interpreted as evidence that the two bioactive glass–containing toothpastes perform equivalently. Further studies with larger, adequately powered sample sizes, or a formally designed equivalence trial, are needed to draw definitive conclusions regarding their comparative efficacy.