en Endodontics Endodontics Original article Original article <div> <table align="center" hspace="0" vspace="0"> <tbody> <tr> <td style="padding: 0cm 12px; text-align: justify;" valign="top"><span style="font-size:13pt"><span new="" roman="" style="font-family:" times=""><b><span style="font-size:9.0pt"><span style="font-family:" verdana=""><span style="color:#2e74b5">Background and Aim</span></span></span></b><b><span style="font-size:9.0pt"><span style="font-family:" verdana=""><span style="color:#2e74b5">:</span></span></span></b><b> </b><span style="font-size:9.0pt"><span style="font-family:" verdana="">Discoloration is an unfavorable side effect of regenerative endodontic procedures using mineral trioxide aggregate (MTA). The efficacy of home bleaching of discolored teeth with carbamide peroxide has not been well investigated, and the minimum required duration of home bleaching is still unclear. This study aimed to compare the effects of different durations of home bleaching on tooth discoloration caused by MTA. &nbsp;</span></span></span></span><br> <span style="font-size:13pt"><span new="" roman="" style="font-family:" times=""><b><span style="font-size:9.0pt"><span style="font-family:" verdana=""><span style="color:#2e74b5">Materials and Methods:</span></span></span></b><span style="font-size:9.0pt"><span style="font-family:" verdana=""> This in vitro, experimental study used 16 tooth blocks of bovine central incisors. To cause discoloration, white MTA was applied for 40 days in cavities drilled in blocks. The color parameters were measured at baseline and at 14, 28, and 42 days after the application of 20% carbamide peroxide using a spectrophotometer. Data were analyzed by repeated measures ANOVA and Tukey&rsquo;s post-hoc test.</span></span></span></span><br> <span style="font-size:13pt"><span new="" roman="" style="font-family:" times=""><b><span style="font-size:9.0pt"><span style="font-family:" verdana=""><span style="color:#2e74b5">Results:</span></span></span></b> <span style="font-size:9.0pt"><span style="font-family:" verdana="">The color change (∆E) value was 22.9&plusmn;10, 26.3&plusmn;10.9, and 27.03&plusmn;11 at 14, 28, and 42 days after bleaching, respectively.<br> Significant color change occurred at 2, 4, and 6 weeks after the application of carbamide peroxide (P<0.001). The color change increased at 42 days (∆E of 3.1, or 13% compared with baseline), which was the highest amount among all time points. However, pairwise comparisons showed that it was not statistically significant (P=0.4).</span></span></span></span><br> <span style="font-size:13pt"><span new="" roman="" style="font-family:" times=""><b><span style="font-size:9.0pt"><span style="font-family:" verdana=""><span style="color:#2e74b5">Conclusion:</span></span></span></b> <span style="font-size:9.0pt"><span style="font-family:" verdana="">It appears that 14 days is the required time for bleaching of teeth discolored by MTA. Longer bleaching times showed insignificantly higher efficacy for tooth whitening. </span></span></span></span></td> </tr> </tbody> </table> </div> <div style="text-align: justify;"></div> Tooth Bleaching, Carbamide Peroxide, Tooth Discoloration, Mineral Trioxide Aggregate 11 17 http://jrdms.dentaliau.ac.ir/browse.php?a_code=A-10-910-1&slc_lang=en&sid=1 Keyvan Saati keivan.saati@gmail.com 100319475328460011366 100319475328460011366 No Department of Restorative Dentistry, Dental Branch, Islamic Azad University of Medical Sciences, Tehran, Iran Ramtin Chitsazha ramtinchitsazha@yahoo.com 100319475328460011367 100319475328460011367 No Department of Periodontics, Faculty of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran Negin Firouzi neginfirouzi@gmail.com 100319475328460011368 0000000196257625 Yes Department of Endodontics, Faculty of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran Sohrab Tour Savadkouhi S_Savadkouhi@yahoo.com 100319475328460011369 100319475328460011369 No Department of Endodontics, Faculty of Dentistry, Islamic Azad University of Medical Sciences, Tehran, Iran Negar Firouzi neg.firouzi@gmail.com 100319475328460011370 100319475328460011370 No Faculty of Dentistry, Islamic Azad Uni-versity of Medical Sciences, Tehran, Iran