Effect of 40% Hydrogen Peroxide with and without Nano-Hydroxyapatite and Nano-Bioactive Glass on the Dentinal Tubular Occlusion: An In Vitro Study

Dental sensitivity is one of the most common complications of bleaching treatments. Several sensitization agents have been used to relieve symptoms. Recently, the use of nanobiomaterials has been considered for dentinal tubular occlusion to treat sensitivities. The purpose of this study was to investigate the effect of 40% hydrogen peroxide with and without nano-hydroxyapatite and nano-bioactive glass on the dentinal tubular occlusion. By removing the cervical enamel of 60 healthy premolar teeth, a flat surface of the dentin was created. The samples were prepared with the same dimensions and randomly divided into three equal groups, including group 1) 40% hydrogen peroxide bleaching material, group 2) combination of bleaching material and nano-hydroxyapatite 2% by weight, and group 3) combination of bleaching material and nano-bioactive glass, 7.5% by weight. Bleaching was performed in three periods of 15 min in two sessions with a one-week interval. Dentinal tubular occlusion was investigated using scanning electron microscope images, and scoring was based on the Hulsmann index. The data were analyzed by the Kruskal-Wallis test and Dunn's multiple comparison test. The significance level was considered 0.05. But group 1 was significantly different from both groups 2 and 3 (P<0.001). In contrast to group 1, the occlusion of dentinal tubules occurred in groups 2 and 3. However, there was no significant difference in the closure of dentinal tubules between groups 2 and 3 (P=0.01). There was a significant difference between the group 1 and group 2 and 3 (P<0.001). Adding nano-hydroxyapatite and nano-bioactive glass to hydrogen peroxide causes the occlusion of dentinal tubules after bleaching, and it can be a successful treatment to reduce post-bleaching sensitivities with hydrogen peroxide.