IRCT20150107020601N2 IRCT 2018-02-10 International Campus - Tehran University of Medical Sciences Vice Dean for reasearch Affairs surgical guide in jaw surgery A Comparative study to assess feasibility of computer assisted designed and fabricated surgical guides in sagittal split osteotomy vs. conventional sagittal split osteotomy. 2018-01-10 anticipated 9 Complete https://irct.ir/trial/28601 interventional Randomization: Randomized, Blinding: Triple blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Randomization description: We will have two study group, the side of mandibular ramus that will be treated by convention osteotomy (can be right or left) and the side that will be treated using the computer designed and manufactured surgical guide of same patient (the other side). For every patient the side of mandibular ramus will be selected by simple random sampling technique (tossing coin). The coin tossing will be used twice to select the side of mandible (right or left) and types of technique (surgical guide assist or conventional), Blinding description: In this study the participant, the outcome assessor and statistician will be blinded, they will not know what treatment is used for which side. The treatment will be registered using a code known only to investigator. N/A Orthognatic surgery, feasibility of computer assisted designed and fabricated surgical guide in sagittal split ramus osteotomy. Intervention 1: Intervention group: The Mandibular ramus side for which computer assisted designed and fabricated surgical guide will be used will intervention group. y. Intervention 2: Control group: The side of Mandible that will be treated with conventional sagittal split osteotomy. Undecided - It is not yet known if there will be a plan to make this available Justification or reason for indecision in sharing IPD is The work has not been started yet