Inferior Maxillary Repositioning Remains Stable 1 Year After Surgery but Entails a High Risk of Osteosynthesis Failure

What is the angular accuracy of regional voxel-based registration for segmental Le Fort I and genioplasty osteotomies?

Among the accuracy analysis techniques for orthognathic surgery, regional voxel-based registration (R-VBR) has robust data, but remains unvalidated for smaller jaw segments. The purpose of this study was to validate the angular accuracy of R-VBR for segmental Le Fort I (SLFI) and genioplasty osteotomies. Postoperative cone beam computed tomography (CBCT) of consecutive patients with three-piece SLFI or genioplasties was rotated to a known pitch/roll/yaw (P/R/Y). Using R-VBR, a copy of the raw CBCT was superimposed onto the rotated CBCT at four mutual regions of interest (ROI): anterior, right posterior, and left posterior maxilla, and chin. The P/R/Y of each was subtracted from those of the rotated CBCT to calculate the angular error. The predictor and outcome variables were ROI and absolute angular error, respectively. The accuracy threshold was 0.5°. Ten SLFI and 34 genioplasties were analyzed based on the sample size calculation. The one-sample t-test and Wilcoxon signed rank test were applied in the analysis. The mean absolute error was 0.20-0.54° for the maxillary segments (all P ≤ 0.01) and 0.83-2.51° for the genioplasty segments (all P < 0.001). R-VBR has variable angular accuracy for SLFI osteotomies and may be insufficient for genioplasty. The findings may allow the design and interpretation of studies on SLFI and genioplasty with greater rigor, thereby contributing to minimizing the discrepancy between planned and achieved outcomes.

Effect of maxillary impaction on mandibular surgical accuracy in virtually-planned orthognathic surgery: A retrospective study

Although surgical accuracy has been evaluated in bi-maxillary procedures, few studies have investigated the relationship between maxillary and mandibular accuracy. The present study evaluated the effect of maxillary impaction accuracy on mandibular surgical outcome. This cohort study analyzed skeletal class III patients who underwent planned maxillary impaction in bi-maxillary surgery. The primary predictor was the difference between the virtual plan and surgical outcome in the maxilla, as determined by three-dimensional (3D) and vertical differences. The secondary predictors were the planned 3D distances in the maxilla and mandible. The primary outcome was mandibular surgical accuracy, defined as the difference between the planned and actual outcomes, calculated as 3D Euclidean distance. The study included 73 patients. Increased differences between the planned and actual outcomes in the maxilla were associated with increased differences in the mandible. The post-operative position of the mandible was closer to the planned position when the position of the impacted maxilla was superior than when it was inferior to the planned position. Moving the maxilla closer to the planned position resulted in a more accurate mandibular position. These findings suggest that careful surgical procedures are needed to avoid inferior positioning of the maxilla during maxillary impaction surgery.

Relapse and temporomandibular joint dysfunction (TMD) as postoperative complication in skeletal class III patients undergoing bimaxillary orthognathic surgery: A systematic review

Objectives

The aim of this study was to determine Relapse and TMD as postoperative complication in skeletal class III patients undergoing bimaxillary orthognathic surgery.

Materials and methods

Data was obtained by database searching using The Cochrane Central Register of Controlled Trials (central), PUBMED, SCOPUS, EMBASE, Google scholar, National Medical library, New Delhi. The titles and abstracts of the electronic search results were screened and evaluated by two observers for eligibility according to the inclusion and exclusion criteria.

Results

5261 articles were retrieved for the review. Among these, 3474 duplicate articles were removed. 418 studies were selected based on the eligibility criteria. For the present review, 30 articles were included after elimination according to the inclusion criteria. The Prisma diagram flowchart demonstrates our selection scheme. Quality assessment criteria to evaluate the studies were decided by two review authors in accordance with CONSORT guidelines. Each study was assessed using the evaluation method described in the Cochrane Handbook for Systematic Reviews. Among the 30 studies included in the review, marked degree of relapse in the mandible was noted from 3 months - 1 year postoperatively in 8 studies, 5 studies reported both TMD prevalence and relapse, whereas only 4 studies reported TMD disorder alone.

Conclusion

Complications of relapse and TMD are associated with bimaxillary orthognathic surgery procedures. More RCTs and CCTs are needed in this regard to get better quality evidence. This review was registered with PROSPERO: CRD42020211342.