A new bleaching technique with nano-hydroxyapatite and 6% Hydrogen peroxide

Introduction: Tooth sensitivity during whitening has been associated with microscopic surface defects and sub-surface pores in enamel. It has been theorized that these defects allow rapid ingress of the whitening agent to the pulp and this results in sensitivity. A product that encourages repair of these microscopic defects can reduce sensitivity. Laboratory studies have shown these microscopic pores can be repaired using a paste containing nano-sized hydroxyapatite (n-HAP). This study evaluated color change, stability, and tooth sensitivity in patients submitted to a new bleaching technique with Nano-Hap and 6% Hydrogen peroxide, whereas the control group used a placebo. Material and methods: 6 patients with intact natural maxillary incisors, free of restorations with a initial shade of A2 or darker according to a value-oriented Vita shade Guide (Vitapan Classical), which had not been subjected to any previous tooth bleaching were included in the study. A spectrophotometer and a Vita shade guide (Vitapan Classical) were used to measure color change before the treatment and after 24 h, 1 week, and one month. A VAS questionnaire was used to evaluate tooth sensitivity before the treatment and following the treatment at 24 h, 1 week, and one month. At each color evaluation an investigator and a trained research assistant evaluated tooth color. Prior to the study research assistants and investigators underwent calibration exercises. For statistical analysis the tabs of the shade were arranged from B1 to C4 from the lightest to the darkest shade. The bleaching material was used according to the manufacturer instructions, Prevdent. (Baroniestraat, Amsterdam, The Netherlands) Statistical Analysis: The change in VAS score before and after the treatment and at any following time point was compared using a Mann–Whitney rank sum test. The percentage of participants experiencing sensitivity before and after the treatment and at any time point was calculated using chi square tests. The color change was assessed before and after the treatment and at any time point using t-test. P-value of 0.05 was considered significant for all analyses. Results and Discussion: The color change measures according to both spectrophotometer and Vita shade guide indicated that positive whitening took place. The teeth were brighter immediately after bleaching and 4 weeks following the end of bleaching. Using Vita shade guide, 4 weeks following the end of bleaching the mean tab changes from baseline were 1.5. There was no significant difference between the spectrophotometer and Vita shade guide for color change measurement before and after the treatment and at any time point. There was no significant difference between the VAS score before and after the treatment and at any time point. Conclusions: Within the limits of the study it can be concluded that use of this new bleaching product containing nano-sized hydroxyapatite (n-HAP) and 6% Hydrogen peroxide is effective as tooth withening technique and does not increase tooth sensitivity during and after the bleaching treatment.