Comparison between one-jaw and two-jaw designs in virtual surgery planning for patients with class III malocclusion

Orthognathic surgery is highly effective for treating maxillomandibular discrepancies in patients with class III malocclusion. However, whether one- or two-jaw surgery should be selected remains controversial. Our study aimed to evaluate quantitative differences between one-jaw and two-jaw surgical designs. In total, 100 consecutive patients with skeletal class III malocclusion who underwent orthognathic surgery with preoperative three-dimensional simulation between August 2016 and November 2021 were recruited. Based on the same final occlusal setup, a two-jaw surgery design and two types of one-jaw design were created. In total, 400 image sets, including preoperative images and three types of surgical simulation, were measured and compared. The one-jaw mandibular setback design led to improvement in most cephalometric measurements and facial symmetry. Although the one-jaw maxillary advancement design improved the ANB angle and facial convexity, it induced maxillary protrusion and reduced facial symmetry. Compared with the other designs, the two-jaw design provided significantly closer cephalometric measurements to the normative values, better symmetry, and less occlusal cant. Overall, the two-jaw design provided a quantitatively better facial appearance in terms of symmetry, proportion, and profile. Although an optimal surgical design necessitates thorough preoperative evaluation and a shared decision-making process, two-jaw surgery can be considered for improving overall facial esthetics and harmony.