eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2015-08-15 12 2 1181 1185 2115 article EzojiFariba 1 Razavi Seyed Jaber 1 Department of Operative Dentistry, Babol University of Medical Sciences, Babol, Iran Tooth bleaching reducesthe surface microhardness of enamel. The aimof this study was to evaluate the effect of CPP-ACP pastewith diode laser simultaneously on surface microhardnessof enamel of bleached teeth. In this in vitro experimental study, forty fivehealthy anterior teeth of bovine were selected and divided into three groups. Basis microhardnessof all the samples was measured by Vickers hardness test. Then all the samples were bleached using 38% H₂O₂ and their surface microhardnesswere measured. Then, the first group was treated with CPP-ACP paste, the second group was irradiated with diode laser,and in the third group CPP-ACP+diode laser   were used simultaneously. Then the microhardnessof enamel wasmeasured again. One-wayANOVA followed by Tukey test was used for statistical analysis. Significanceset  was considered at p<0.05. Tooth bleaching reduced surface microhardness of enamel. The final microhardness of CPP-ACP group hasshown significant increase compared to the diode laser group (p=0.001), while microhardness of enamel in the first group did not show significant difference compared to the CPP-ACP +diode laser  group (p=0.80). use of CPP-ACP paste increasesmicrohardnessof enamelafter bleaching. But use of diode laser associated with CPP-ACP paste does not have any influence on performance ofCPP-ACP paste. https://www.biotech-asia.org/vol12no2/changes-in-bleached-enamel-microhardness-after-application-of-casein-phosphopeptide-amorphous-calcium-phosphate-cpp-acp-and-diode-laseran-in-vitro-study/ Surface Microhardness; Diode Laser; Tooth Bleaching; CPP-ACP