Orthognathic surgery is a multidisciplinary treatment performed jointly by orthodontists and oral and maxillofacial surgeons to correct dentofacial deformities in skeletally mature patients with significant jaw discrepancies (Reyneke and Ferretti, 2002). These deformities often affect appearance and function, impairing mastication, speech, and temporomandibular joint (TMJ) health (Arslan et al., 2014). The primary goals of orthognathic surgery are to restore proper occlusal relationships, improve facial balance, and maintain long-term skeletal stability.

Among the various orthognathic techniques, bilateral sagittal split osteotomy (BSSO) is one of the most commonly used approaches for repositioning the mandible. First introduced by Obwegeser and Trauner in 1955 (Obwegeser, 1957) and later modified by Hunsuck (Al-Nawas et al., 2014) BSSO allows controlled, three-dimensional movement of the mandibular segments. Despite its reliability and widespread use, complications such as unfavorable fractures, often referred to as “bad splits” can occur. These fractures may deviate from the intended osteotomy line, extending into the buccal or lingual cortex, coronoid process, or condylar neck, which can complicate fixation and postoperative healing (Ochs, 2003).

The presence of mandibular third molars, particularly when impacted, has been frequently discussed as a possible factor contributing to bad splits. Because of their close proximity to the osteotomy line, these teeth may reduce local bone resistance or alter fracture trajectories during splitting. However, there is still no consensus on whether third molars should be removed before surgery, extracted during the procedure, or retained. Similarly, the effects of their impaction depth or anatomical angulation on fracture risk remain uncertain.

This study aimed to investigate whether the presence, impaction status, and anatomical position of mandibular third molars influence the incidence of bad splits during BSSO. We hypothesized that retained third molars, particularly in older patients or when deeply impacted, may increase the risk of unfavorable fracture patterns. To address this, we compared the frequency and types of bad splits in patients with and without third molars. We analyzed whether impaction status or anatomical position affected these outcomes.