Effects of bleaching agents on the micro hardness of composite materials; a tooth colored restorative material

Abstract

Over the last several decades, tooth bleaching has been considered as one of the most popular cosmetic dentistry procedures which have been linked to changes in the surface and subsurface micro-hardness, color, surface topography and surface roughness, of restorative substances. The aim of the study is to evaluate the effects of bleaching agents on the micro-hardness of tooth colored restorative materials. This study was carried out from 1st July, 2021 to 31st December, 2021 at the Department of Dental Materials, Sardar Begum Dental College, Gandhara University, Peshawa. Nanofill composite and micro hybrid composite, were used in our study to prepare 30 disc samples. Power bleaching material Pola Office (with 35% hydrogen peroxide) and night guard vital bleaching material Pola Night (with 16% carbamide peroxide concentration) were used as bleaching agent in our study. After the bleaching procedure the final micro hardness values were quantified. SPSS version 23 was used to analyze all of the results. The mean (±SD) difference in micro hardness of microhybrid composite materials after bleaching with 35% hydrogen peroxide and 16% carbamide peroxide was 8.88 (0.95) and 7.38 (2.0) respectively. While the mean (±SD) difference in micro hardness of nanofill composite material after bleaching with 35% hydrogen peroxide and 16% carbamide peroxide was 7.90 (2.09) and 4.25 (1.10) respectively. Only microhybrid composite materials shows statistically significant reduction in micro hardness after treatment with 35% hydrogen peroxide (p=0.021). In our study, significant micro hardness reduction occurs in micro hybrid composites by using 35% hydrogen peroxide. No or little affect was observed on micro hardness of nanocomposites and micro hybrid with 16% carbamide peroxide bleaching agent.