Eshghpour Majid, Labafchi Ali, Samieirad Sahand, Hosseini Abrishami Majid, Nodehi Elham, Rashid Javan Abdollah
Oral and Maxillofacial Diseases Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Student Research Committee, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.
World J Plast Surg. 2021 Jan;10(1):37-42. doi: 10.29252/wjps.10.1.37.
The possibility of mandibular bad spilt might happen during bilateral sagittal split osteotomy (BSSO). This study investigated the effect of impacted mandibular third molars on bad spilt incidence during BSSO.
Totally, 140 patients under 40 years old who were candidates for BSSO surgery due to class 3 skeletal discrepancy were divided randomly into two equal groups. The impacted mandibular third molars were presented in one group during BSSO (Exposed), and the third molars were removed at least six months before surgery for the other group (Unexposed). All cases underwent BSSO using the same technique by a single surgeon. A bad split was diagnosed by inter-operative clinical examination and postoperative panoramic radiography.
Four bad split occurrences were observed including three patients in the group which impacted mandibular third molars were presented and one patient in the group without impacted mandibular third molars. The incidence of bad fracture in the exposed group was 3.7 times more than the unexposed group. The incidence of the bad fracture in exposed group was 3.7 times more than unexposed group. The chance of fractures in females was 1.7 times higher than males. With one year addition to the patient's age, chance of fracture increased 0.985 times more.
Overall incidence of bad split fracture in presence of mandibular third molars in females and at older ages increased during BSSO. The extraction of impacted mandibular third molars, six months before the BSSO is recommended to prevent the bad split incidence during the operation.
双侧矢状劈开截骨术（BSSO）过程中可能发生下颌骨不良劈开。本研究调查了下颌阻生第三磨牙对BSSO期间不良劈开发生率的影响。
总共140例因Ⅲ类骨骼畸形而适合进行BSSO手术的40岁以下患者被随机分为两组，每组人数相等。一组在BSSO期间存在下颌阻生第三磨牙（暴露组），另一组在手术前至少6个月拔除了第三磨牙（未暴露组）。所有病例均由同一位外科医生采用相同技术进行BSSO。通过术中临床检查和术后全景X线摄影诊断不良劈开。
观察到4例不良劈开事件，其中下颌阻生第三磨牙存在组有3例患者，无下颌阻生第三磨牙组有1例患者。暴露组的不良骨折发生率比未暴露组高3.7倍。女性骨折的几率比男性高1.7倍。患者年龄每增加一岁，骨折几率增加0.985倍。
在BSSO期间，女性及年龄较大患者存在下颌第三磨牙时，不良劈开骨折的总体发生率增加。建议在BSSO前6个月拔除下颌阻生第三磨牙，以防止手术期间发生不良劈开。
