One-year assessment of surgical outcomes in Class III patients using cone beam computed tomography

Abstract

The purpose of this study was to apply a novel method to evaluate surgical outcomes at 1 year after orthognathic surgery for Class III patients undergoing two different surgical protocols. Fifty patients divided equally into two groups (maxillary advancement only and combined with mandibular setback) had cone beam computed tomography (CBCT) scans taken pre-surgery, at splint removal, and at 1-year post-surgery. An automatic cranial base superimposition method was used to register, and shape correspondence was applied to assess, the overall changes between pre-surgery and splint removal (surgical changes) and between splint removal and 1-year post-surgery at the end of orthodontic treatment (post-surgical adaptations). Post-surgical maxillary adaptations were exactly the same for both groups, with 52% of the patients having changes >2 mm. Approximately half of the post-surgical changes in the maxilla for both groups were vertical. The two-jaw group showed significantly greater surgical and post-surgical changes in the ramus, chin, and most of the condylar surfaces (P < 0.05). Post-surgical adaptation on the anterior part of the chin was also more significant in the two-jaw group (P < 0.05). Regardless of the type of surgery, marked post-surgical adaptations were observed in the regions evaluated, which explain the adequate maxillary–mandibular relationship at 1-year post-surgery on average, with individual variability.

Three‐dimensional regional displacement after surgical–orthodontic correction of Class III malocclusion

“…The analysis of the average surgical and postoperative displacements for each anatomic region and the descriptive statistics for this sample have been described in detail by De Paula et al .…”

“…This study performed secondary data analysis of existing data prospectively collected from 50 patients (23 male, 27 female: mean age 24.7 years old) who had undergone orthognathic surgery, after approval of the Institutional Review Board of the University of North Carolina. All the patients had skeletal Class III discrepancies with edge‐to‐edge occlusion or negative overjet.…”

“…). The shape correspondence method, SPHARM‐PDM software, was introduced by Styner et al and later applied to orthognathic surgery patients by other authors . The distance maps provided the magnitude of the position changes between two point‐based correspondent models, while the vector maps provided the directionality of these positional displacements.…”

“…De Paula et al applied a novel method to quantify surface displacements using cranial base superimposition and compared changes due to surgery (6‐week follow‐up) and post‐surgical adaptation (1‐year follow‐up) for Class III patients undergoing 2‐jaw surgery or maxillary advancement only. Those results revealed greater individual variability than previous 2D findings and led to the questions addressed in this study about possible associations between the skeletal maxillary and mandibular post‐surgical adaptations that may affect the stability of the surgical correction.…”

Use of shape correspondence analysis to quantify skeletal changes associated with bone-anchored Class III correction

“…Despite the fact that SPHARM-PDM analysis has been used to evaluate maxillary changes in surgical patients, 18 there are challenges for the application of SPHARM-PDM quantitative image analysis to the maxilla in growing patients. Unlike the mandible, the maxilla is not an isolated bone, and the maxillary boundaries are not visible in surface models constructed from CBCT.…”