en تخصصي Special مقالات اصيل Original Article <strong>BACKGROUND</strong><br> We aimed to assess the incidence of bad split fractures during Bilateral Sagittal Split Osteotomy (BSSO) mandibular setback surgery using Dal Pont and Hunsuck techniques.<br> <strong>METHODS</strong><br> All healthy adults with skeletal class III discrepancy, who were candidates for mandibular setback surgery were enrolled in this randomized clinical trial in the Maxillofacial Surgery Department of Qaem Hospital, Mashhad, Iran; from 2018-2020. These patients were randomly divided into two equal groups; one group underwent BSSO using Dal Pont osteotomy while the Hunsuck osteotomy was employed for the other group. A bad split fracture which identified through intra-operative clinical and postoperative radiographic examination was the outcome variable. The significance level was set at 0.05 using SPSS 16.<br> <strong>RESULTS</strong><br> Overall, 104 consecutive patients, comprising of 52 (50%) males with an average age of 23.09&plusmn;3.08 were recruited. The average duration of osteotomy and splitting was reported to be 22.74&plusmn;3.06 min. 10 bad split fractures (9.62%) were observed; 7 of which occurred in the Dal Pont group and 3 in the Hunsuck group. However, this difference was not significant. In 80% of the cases, bad split osteotomy occurred in the proximal segment, while this finding was identified in the distal segment in 20% of cases. The average duration of osteotomy and splitting was significantly longer in the Dal Pont group (<em>P</em><0.001).<br> <strong>CONCLUSION</strong><br> The duration of osteotomy and splitting is much shorter when the Hunsuck technique is employed, and the incidence of unfavorable fractures is also less compared to the Dal Pont osteotomy technique. BSSO, Bad split, Dal pont osteotomy, Hunsuck osteotomy 25 33 http://wjps.ir/browse.php?a_code=A-10-466-28&slc_lang=en&sid=1 Farhad Zeynalzadeh 100319475328460011607 100319475328460011607 No Oral and Maxillofacial Department, Mashhad University of Medical Sciences, Mashhad, Iran Zahra Shooshtari 100319475328460011608 100319475328460011608 No Student Research Committee, Mashhad University of Medical Sciences, Mashhad, Iran Majid Eshghpour 100319475328460011609 100319475328460011609 No Oral and Maxillofacial Diseases Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. Seied Hosein Hoseini Zarch 100319475328460011610 100319475328460011610 No Oral and Maxillofacial Radiology, Oral and Maxillofacial Diseases Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. Elahe Tohidi 100319475328460011611 100319475328460011611 No Dental Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. Sahand Samieirad 100319475328460011612 100319475328460011612 Yes Dental Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.