Fracture Pattern Following Bilateral Sagittal Split Osteotomy With or Without Impacted Third Molars

Fracture pattern following BSSO with or without impacted third molars

The fracture pattern of the mandible following BSSO will be assessed by CBCT scans (i-CAT; Imaging Sciences International, Hatfield, PA, USA) obtained preoperatively, and one week after surgery. The CBCT will be taken by fixed exposure parameters of 120 kV, 160 × 60 mm field of view, 0.30 mm voxel size, and 8.9-second images. The fracture pattern of the mandible will be classified according to LSS by the study investigator (KBØ). The LSS consisted of 4 categories based on the path of the fracture line on the lingual side of the mandibular ramus.

Condylar segment position following BSSO with or without impacted third molars

The mandibular condylar segment positioning will be assessed in the sagittal, vertical, and transverse dimension by superimposing the pre- and postoperative CBCT scan using dedicated software (OnDemand3D Application, version 10; Cybermed, Seoul, South Korea). The orbital bony walls on the preoperative CBCT will be used as the reference and matched with the orbital walls on the postoperative CBCT. Pair-wise registration will be done, based on the automated detection of hundreds of virtual landmarks in the volumes, which can subsequently be manually adjusted, based on visible anatomical landmarks.To estimate the condylar displacement in all three dimensions, the intertransverse distance in millimeters between the center of the condyles is measured on the pre- and postoperative CBCT. Moreover, the distance between the mandibular condyle to the glenoid fossa is measured in the sagittal and vertical dimension. The measurements will be conducted by the study investigator (KBØ).

Oral Health Impact Profile-14 (OHIP-14)

OHIP-14 is a validated questionnaire for assessment of OHRQoL. OHIP-14 states the patient's overall oral impairment and does not take a specific treatment site into account. OHIP-14 is organized into seven conceptual dimensions including functional limitation, physical discomfort, psychological discomfort, physical disability, psychological disability, social disability and handicap. The response format of OHIP-14 is: Very often = 4; Fairly often or many times = 3; Occasionally = 2; Hardly ever or nearly never = 1; Never/I don´t know = 0. Thus, OHIP-14 scale ranged from 0 to 56 and dimension score ranged from 0 to 8. Values of the 14 items and each dimension are summed to calculate the OHIP-14 severity score and higher scores indicate poorer OHRQoL

The Modified Dental Anxiety Scale (MDAS)

The level of preoperative dental anxiety is assessed by MDAS, which is a brief questionnaire rating patient's emotional reaction to an up-coming dental visit.MDAS consist of five questions in a Likert scale ranging from not anxious (scoring 1), slightly anxious (scoring 2), fairly anxious (scoring 3), very anxious (scoring 4) to extremely anxious (scoring 5) and summed together to produce a total score ranging from 5 to 25. For assessing the level of dental anxiety of each patient, response scores of all 5 questions are added. The total score ranges from 5 to 25 with cut-off scores 14 and 19 suggestive of high dental anxiety and dental phobia.

Length of the surgical procedure

The intraoperative length of BSSO will be measured by a stopwatch (iPhone 14 Pro or similar) from the incision to the last suture in both groups. The intraoperative length of BSSO will be registered by the surgeon.

Intraoperative bleeding

The intraoperative blood loss will be estimated by measuring suctioned blood, and then adjusted for the used volume of saline irrigation during BSSO. If the patient is undergoing bimaxillary surgery, then the blood loss will solely be calculated and registered for the BSSO. The intraoperative blood loss will be registered by the surgeon.

Frequency of intra- and postoperative complications

Frequency of intra- and postoperative complications including visualization and injury of the inferior alveolar nerve, heavy bleeding, or unfavorable fracture patterns will be registered by the surgeon. Postoperative complications including temporary or permanent neurosensory disturbances of the inferior alveolar nerve and infection will be registered by the surgeon. Infection will be registered according to the criteria for surgical site infection event (SSI) stated by the center of disease control.