Color and Surface Effects of Experimental Bleaching Gel on Enamel

Objectives: This in-vitro study is to investigate whitening efficacy and effects on enamel surface of experimental home-bleaching gels containing chitosan nanoparticles loaded with controlled release extracts of Gypsophila arrostii combined with hydrogen peroxide/HP or carbamide peroxide/CP.
Methods: Ninety-six intact human premolar teeth were divided into eight groups (n=12) as negative control (NC); experimental groups: 6%HP Opalescence Go (Ultradent)(OGO), and 16%CP Opalescence (Ultradent)(OPF), Chitosan (C), Gypsophila extract (GE), Gypsophila extract-loaded chitosan nanoparticles (GECNP), GECNP+6%HP (GECNP-HP), GECNP+16%CP(GECNP-CP). The crowns of the teeth were embedded in acrylic resins, with the labial surfaces positioned externally. Bleaching procedures were conducted with custom-made bleaching-trays for 2 weeks for each group except NC. Color was measured with a spectrophotometer (Easyshade-V, VITA) at three-time intervals: before bleaching, 14-days, and 6-months after bleaching. Specimens were visualized using Smile Lite MDP2 (Smile Line) with its cross-polarizing filter and examined with a light-fluorescent system (FluoreCam,Daraza) and field emission scanning electron microscope (FESEM)(Apreo S2,ThermoFischer Scientific). The data were analyzed using one-way analysis of variance, Kruskal-Wallis H and Friedman test (IBM SPSS Statistics 23). The significance level was set at p<0.05.
Results: No statistically significant difference was observed between GECNP-HP and GECNP-CP and OPF and OGO regard to ΔE, and ΔL values before and after bleaching (14-days or 6-months) (p>0.05), however, a significant difference was found between them and NC-group (p<0.05). The experimental bleaching gels demonstrated "excellent whitening efficacy" as evidenced by their remaining above the threshold value ΔE00>5.4. Specimens exposed to peroxide-based gels observed shallow erosion, increased porosity, and noticeable surface changes.
Conclusions: Experimental peroxide-based home-bleaching gels, incorporating chitosan nanoparticles loaded with controlled-release Gypsophila extract, showed excellent whitening efficacy after 14-days bleaching treatment and color stability after 6-months aging. Gypsophila extract, may offer a viable and promising alternative for preserving enamel surface properties while achieving effective whitening