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Effect of occlusal vertical dimension changes on postsurgical skeletal changes in a surgery-first approach for
Jihyun Lee1, Yong-Il Kim2, Dae-Seok Hwang3
1Postgraduate student, Department of Orthodontics, Pusan National University Hospital, Busan, South Korea.
Introduction:
The purposes of this study were to investigate the relationship between occlusal vertical dimension (VD) changes and postsurgical skeletal changes in the surgery-first approach and to derive regression models for the final mandibular setback at B-point.
Methods:
This retrospective study included 40 patients (16 men, 24 women; ages, 22.6 ± 4.0 years) who had undergone a bimaxillary surgery-first approach. Using cephalograms generated from cone-beam computed tomography representing the presurgical, postsurgical, and posttreatment stages, skeletal landmarks in the maxilla and mandible were investigated to derive multivariate linear regression-based prediction models. Additionally, a patient classification based on the VD was established and verified to generate regression models for the classified groups.
Results:
For the nonincreased VD group, the surgical setback of B-point was its predictor for the final mandibular setback (R(2) at 92%). Meanwhile, the final mandibular setback of the increased VD group was predicted according to the surgical upward movement of pogonion, the postsurgical horizontal position of A-point, and the postsurgical vertical position of the coronoid process (R(2) at 94%).
Conclusions:
The results of this study support the clinical observation that the more increased the vertical occlusal dimension after surgery, the less predictable the position of B-point at the posttreatment stage.
