en دندانپزشکی ترمیمی Operative dentistry پژوهشي Research <span style="font-size:12px;"><span style="line-height:200%"><span new="" roman="" times=""><strong>Background:</strong> Tooth bleaching materials have the potential to alter both the organic and mineral components of dental tissues, which may in turn affect enamel surface morphology. This study aimed to evaluate the effect of at-home bleaching on the i<strong>ncrease</strong><strong><span style="font-weight:normal"> of Enamel Microcracks.</span></strong></span></span><br> <span style="line-height:200%"><span new="" roman="" times=""><b>Materials and Methods:</b> In this in vitro experimental study, 40 extracted anterior teeth were randomly divided into two groups. Baseline stereomicroscopic images of the buccal surfaces were captured to record the initial number of enamel microcracks. Each tooth was measured at multiple regions before and after bleaching to allow repeated assessments. Group 1 was treated with 15% carbamide peroxide, and Group 2 with 20% carbamide peroxide, for ten consecutive days. Each day, teeth in Group 1 were exposed to the bleaching agent for 6 hours, and teeth in Group 2 for 4 hours. Stereomicroscopic images were taken after treatment, and the number of microcracks was recorded in all regions. Data were analyzed using a repeated-measures ANOVA with &alpha; = 0.05.</span></span><br> <span style="line-height:200%"><span new="" roman="" times=""><b>Results: </b>The mean number of enamel microcracks increased significantly in both groups after bleaching compared to baseline measurements (p < 0.001). No statistically significant difference was observed between the two concentrations in terms of microcrack formation (p = 0.687).</span></span><br> <span style="line-height:200%"><span new="" roman="" times=""><b>Conclusion:</b> At-home bleaching with both 15% and 20% carbamide peroxide significantly increased the mean number of enamel microcracks. However, the extent of microcrack formation did not differ significantly between the two concentrations.</span></span></span><br> &nbsp; 46 53 http://cofs.khuisf.ac.ir/browse.php?a_code=A-10-1-67&slc_lang=en&sid=1 Roshanak Yousefi 1003194753284600989 1003194753284600989 No Faculty of Dentistry, Isf.C, Islamic Azad University, Isfahan, Iran Mohammad Reza Malekipour 1003194753284600990 1003194753284600990 Yes Department of Operative Dentistry, Faculty of Dentistry, Isf.c, Islamic Azad University, Isfahan, Iran Mehrdad Kazemian 1003194753284600991 1003194753284600991 No Department of Operative Dentistry, Faculty of Dentistry, Isf.c, Islamic Azad University, Isfahan, Iran Mona Fatemeh Rabiei 1003194753284600992 1003194753284600992 No Department of Operative Dentistry, Faculty of Dentistry, Isf.c, Islamic Azad University, Isfahan, Iran