Tehran University of Medical Sciences Journal of Craniomaxillofacial Research 2345-5489 7 4 2021 02 21 203 212 Amir Jalal Abbasi Craniomaxillofacial Research Center, Tehran University of Medical Sciences, Department of Oral and Maxillofacial Surgery, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran; Department of Oral and Maxillofacial Surgery, School of Dentistry, International Campus, Tehran University of Medical Sciences, Tehran, Iran. Abbas Azari Department of Prosthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran. Mehrnoush Momeni Craniomaxillofacial Research Center, Tehran University of Medical Sciences, Department of Oral and Maxillofacial Surgery, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran; Department of Oral and Maxillofacial Surgery, School of Dentistry, International Campus, Tehran University of Medical Sciences, Tehran, Iran. Ahmad Reza Shamshiri Research Center for Caries Prevention, Dentistry Research Institute, Department of Community Oral Health, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran. Shimelis Megersa Gema Department of Oral and Maxillofacial Surgery, School of Dentistry, International Campus, Tehran University of Medical Sciences, Tehran, Iran; Department of Oral and Maxillofacial Surgery, Institute of Health, Jimma University, Jimma, Ethiopia. 2021 02 21 Background: The surgical guide enabled the surgeon to accurately perform osteotomy, minimize iatrogenic injury to vital structure in vicinity to osteotomy and moving the bony segments to desired position exactly as planned during computer simulation. The purpose of this study is assess the role of computer assisted designed and manufactured surgical guide in minimizing inferior alveolar nerve injury during sagittal split ramus osteotomy (SSRO). Materials and Methods: A prospective double blind, randomized controlled, clinical trial is designed to assess role of computer assisted designed and manufactured surgical guide in minimizing inferior alveolar nerve injury during sagittal split ramus osteotomy (SSRO). We had two study group, the side of mandibular ramus that were treated by conventional SSRO (can be right or left) and the side that was treated using the computer designed and manufactured surgical guide of same patient (can be right or left side). For every patient the side of mandibular and osteotomy technique was selected by simple random sampling technique (double coin tossing). The statistical analyses were performed using SPSS version 25 (statistics package for social sciences, Chicago. IL). Statistical significance threshold was set to 0.05 (p-value<0.05). Result: The study population consisted of 10 subjects undergoing SSRO (Sagittal split ramus osteotomy). Seven (70%) were female and three were male. Their mean (±SD) age was 22.4±3024 yrs., range 16 to 27. The mean (±SD) duration of osteotomy on surgical guide assisted SSRO side was 37.2±4.83 and for conventional SSRO side it was 28.2±4.10 and the difference is statistically significant. Conclusion: Using CAD/CAM surgical guide for SSRO has no significant difference with conventional osteotomy technique regarding minimizing the incidence of inferior alveolar nerve injuries that occurs intraoperatively. Keywords: Sagittal split ramus osteotomy; Surgical guide; Neurosensory disturbance; Computer. https://jcr.tums.ac.ir/index.php/jcr/article/view/363 https://jcr.tums.ac.ir/index.php/jcr/article/download/363/310