Influence of Irrigation Protocol on Peroxide Penetration into Dentinal Tubules Following Internal Bleaching: A Confocal Laser Scanning Microscopy Study

Introduction: Discoloration of anterior teeth can result in cosmetic impairment in young children. The walking bleach technique stands out because of its esthetic results with minor side effects. Little information is available regarding the influence of various irrigation solutions on peroxide penetration. The aim of this study is to evaluate the influence of different irrigation protocols on peroxide penetration into dentinal tubules using confocal laser scanning microscopy (CLSM). Study design: Cavity preparations were made in 50 extracted permanent premolars. The teeth went through different irrigation sequences: A. control B. saline C. EDTA, NaOCl D. phosphoric acid E. EDTA, NaOCl, phosphoric acid. Then, mixture of fluorescent dyed sodium perborate paste was placed along the pulp chamber and the coronal access cavity, and was refilled at days 7, 14 and 21. Results: The minimal and maximal penetration depths were 324 and 3045 mu m, respectively, with a mean of 1607 mu m. The stained areas were significantly larger in the buccal and lingual directions (P<0.05). Groups B and C showed significantly larger penetration in weeks 2 and 3 compared to week 1 (P<0.05). Group D and E showed significantly larger penetration compared to groups B and C at all times (P<0.05). Conclusion: Bleaching agents penetrate to the extra-radicular region of teeth; however, the level of peroxide penetration is significantly higher when the irrigation sequence consists of phosphoric acid prior the bleaching agent placement.