Influence of different techniques for bilateral sagittal split osteotomy on the fracture pattern of the mandibular ramus in the context of orthognathic surgery: a cadaver study

错牙合畸形的临床表现是多种多样的，取决于多种影响因素，且常伴有咬合和关节功能障碍。通过手术干预，可以影响和改善颌关节的位置。双侧矢状劈开截骨术（BSSO）是治疗这些复杂病例的首选手术方法。最常见的并发症是严重的劈裂（定义为下颌骨近端或远端不必要的骨折）和神经感觉障碍，这是由于手术中损伤下牙槽神经（IAN）而导致的，会影响患者的日常生活。已经提出了对该技术以及手术器械的修改来解决这些问题。虽然截骨术可以通过钻头、锯或超声器械完成，但大多数用于分离下颌骨远端和近端节段的技术都是基于使用凿子。根据标准方案进行劈裂手术，在下颌角前进行侧皮质切开术，并在下颌骨下缘实施进一步的截骨线身体选择性地使用传统钻头或超声手术进行截骨术，然后使用连接到扭矩计的凿子进行劈裂。这导致四个研究组：1。标准程序/钻孔，2.）标准程序/超声波3.）改良手术/钻头，4.）改良手术/超声研究的目的是不同的双侧矢状劈开截骨术技术和器械对舌骨骨折模式、不良劈开发生率、下牙槽神经状态和劈开所需力的影响。应寻求一种理想的操作程序，以降低目前的高风险。

The appearances of malocclusions are manifold and depend on various influencing factors and often occur with functional impairments of occlusion and articulation. By surgical intervention, the position of the jaw joint can be affected and improved. The bilateral sagittal split osteotomy (BSSO) is the surgical procedure of choice to treat these complex cases. Therefore, the lower jaw is detached from the base and repositioned.The most common complications are bad splits (defined as unwanted fractures of the proximal or the distal segment of the mandible) and neurosensory disturbances, resulting from injury to the inferior alveolar nerve (IAN) during surgery, which can affect the daily life of patients. Modifications to this technique as well as the surgical devices have been proposed to address these issues. While osteotomy can be done by bur, saw or ultrasonic device, most techniques for separation of the distal and proximal segments of the mandible based on the use of a chisel.In this planed cadaveric investigation, a split procedure is done according to the standard protocol with a lateral corticotomy anterior to the mandibular angle as well as a modified technique implementing a further osteotomy line at the inferior border of the mandibular body. The osteotomy is performed selectively with conventional drills or ultrasonic surgery followed by a split using a chisel connected to a torque gauge. This results in four study groups: 1.) Standard procedure/drill, 2.) Standard procedure/ultrasonic 3.) Modified procedure/drill, 4.) Modified procedure/ultrasonicThe objective of the investigation is the influence of different techniques and devices for bilateral sagittal split osteotomy on lingual fracture patterns, incidence of bad splits, status of the inferior alveolar nerve, and the necessary force for the split. An ideal operation procedure should be found to reduce the current high risk.