Add on Calcium Cyclotriphosphate to Hydrogen Peroxide Bleaching Gels May Minimize Enamel Damage: Study Finds
Brazil: Researchers have found in a new study that the addition of calcium-substituted sodium trimetaphosphate (CaNaTMP) to 17.5% and 35% hydrogen peroxide (HP) bleaching gels improves safety and biocompatibility by minimizing enamel damage. The findings were published online in the Journal of Dentistry.
Hydrogen peroxide is widely used in dental bleaching treatments but is often associated with adverse effects such as mineral loss, increased surface roughness, and morphological alterations in enamel. Additionally, the diffusion of hydrogen peroxide through the enamel and dentin can pose risks to the underlying dental structures. To mitigate these concerns, Alberto Carlos Botazzo Delbem, Department of Preventive and Restorative Dentistry, Araçatuba School of Dentistry, São Paulo State University (UNESP), Araçatuba, SP, Brazil, and colleagues aimed to synthesize and assess the in vitro effects of different concentrations (0.25%, 0.5%, and 1%) of CaNaTMP incorporated into 17.5% and 35% hydrogen peroxide (HP) whitening formulations on enamel color change, microhardness, morphology, surface roughness, mineral content, and the transamelodentinal diffusion of HP.
For this purpose, the researchers allocated 288 enamel/dentin discs into eight groups based on the bleaching gel composition, incorporating 35% or 17.5% hydrogen peroxide with or without varying concentrations (0.25%, 0.5%, and 1%) of calcium-substituted sodium trimetaphosphate.
The gels were applied for 40 minutes over three weekly sessions. Assessments included color change (ΔE, ΔE00, ΔWID), surface hardness (SH), surface roughness (Ra), enamel mineral content, and transamelodentinal diffusion of HP. Enamel surface characteristics were analyzed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX). Data were evaluated using ANOVA and the Student-Newman-Keuls test.
The study led to the following findings:
- All bleaching gels induced significant color changes after treatment, with comparable ΔE, ΔE00, and ΔWID values across groups.
- Mineral loss (SH, gHAp × cm⁻³ × µm), surface roughness (Ra), and HP diffusion were highest with the 35% HP gel and lowest in groups containing CaNaTMP, particularly at 1%.
- SEM/EDX analysis showed no visible surface alterations in the 17.5% HP group, while the 1% CaNaTMP-containing group exhibited prominent amorphous apatite precipitation.
- Adding CaNaTMP, especially at 0.5% and 1%, to the 35% HP gel minimized surface changes.
The researchers demonstrated that incorporating CaNaTMP into 17.5% and 35% HP bleaching gels effectively reduced mineral loss, surface roughness, and enamel morphology alterations while limiting trans-amelodentinal diffusion of H₂O₂, without affecting bleaching efficacy. The protective effects were more pronounced with 1% CaNaTMP, particularly in preserving enamel integrity.
"By enhancing the safety and biocompatibility of bleaching gels, this approach offers a promising strategy for minimizing enamel damage. The combination of 17.5% HP with 1% CaNaTMP emerged as a safer and effective whitening option, improving patient comfort during treatment," the researchers concluded.
Reference:
Nunes, G. P., Batista, G. D. F., De Toledo, P. T. A., Martins, T. P., Alves, R. D. O., Fernandes, A. V. P., & Delbem, A. C. B. (2025). Synthesis and application of calcium cyclotriphosphate in bleaching formulations: Effects on dental enamel properties. Journal of Dentistry, 155, 105614. https://doi.org/10.1016/j.jdent.2025.105614
