Effects of Different Occlusion Setups with a Surgery-First Approach and Simulated Presurgical Orthodontics on the Mandibular Position in Skeletal Class III Malocclusion

Purpose: The purposes of this study were to compare the occlusion designs implemented for the surgery-first approach (SFA) and the resultant mandibular movements by different orthodontists, as well as to investigate whether presurgical dental alignment is associated with mandibular positioning. Methods: This prospective study included 15 patients with skeletal Class III malocclusion who underwent orthognathic surgery through the SFA. Three orthodontists designed an occlusion setup for each case, which were assigned as SFA groups. The same group of patients, who received simulated presurgical orthodontics (SPO) through a virtual setup, composed the control group. The postoperative dental relationship and resultant mandibular movements were compared within the SFA groups and also with the SPO group. Three-dimensional skeletal and dental variables were measured and compared using simulation software. Results: No significant differences in the mandibular movement and dental relationship were observed among the three SFA groups. A significant increase in the vertical dimension (VD) of the posterior mandible was observed in the SFA groups, whereas it was reduced in the SPO group. Conclusion: Orthodontists with different occlusion setup details had similar design strategies and were able to manage the SFA with compatible outcomes. Surgical orthodontic treatment without preoperative dental alignment results in an increased VD in the posterior mandible during surgery.