Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Dental Materials

The aim of this study was to evaluate the efficacy of intracoronal bleaching using non thermal atmospheric pressure plasma and its effect on pulp chamber dentin structure. Two types of commercially available hydrogen peroxide bleaching systems were used in this study with a concentration of 32%. Sixty single rooted premolars were selected. All the teeth were sectioned in half longitudinally in a mesio-distal direction. Then, specimens were prepared according to the testing method used. The specimens were stained with a standardized prepared coffee solution. The sectioned teeth were divided into four groups according to the type of bleaching protocol used. Color measurements were done by a spectrophotometer before bleaching, one day and one week after bleaching for all the experimental groups. Digital thermocouple thermometer was used to determine intrapulpal temperature changes for all the experimental groups. Universal Testing Machine was used for measuring microshear bond strength of the four investigated groups before and after bleaching. Microstructure evaluation of the experimental groups was done using SEM before and after the bleaching procedure. The results showed that non thermal atmospheric plasma has a stronger bleaching effect than LED light when used as an activating method. Furthermore, the light bleached group showed a significant decrease in the microshear bond strength values after bleaching as well as a pronounced increase in temperature. Minimum alteration of dentin surface morphology was evident in all bleaching protocols. The application of non thermal atmospheric pressure plasma is a promising method for intracoronal bleaching

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