Three-dimensional quantitative changes of condyle in patients with skeletal class III malocclusion after bimaxillary orthognathic surgery with 5-year follow-up

Three-Dimensional Evaluation of Changes in Condylar Position After Orthognathic Surgery With Different Types of Jaw Deformities

BACKGROUND

Assessing condyle position postorthognathic surgery is pivotal for optimizing surgical accuracy, sustaining postoperative stability, and ensuring predictable treatment outcomes.

PURPOSE

The aim of this study was to analyze the changes of condyle position after orthognathic surgery with different types of jaw deformity and to analyze whether the changes of condyle position are different.

STUDY DESIGN, SETTING, SAMPLE

A retrospective cohort study was designed and conducted, involving adults who underwent orthognathic surgery for jaw deformities at the affiliated Stomatological Hospital of Nanchang University between 2019 and 2022. Patients with incomplete computerized tomography data were excluded.

PREDICTOR/EXPOSURE/INDEPENDENT VARIABLE

The primary predictor variable was time (preoperative and postoperative) and types of jaw deformities (skeletal Class III, skeletal Class II, and mandibular deviation).

MAIN OUTCOME VARIABLE(S)

The main outcome variables were the three-dimensional linear and rotational positional changes of the condyle.

COVARIATES

Evaluated covariates included sex and age.

ANALYSES

MIMICS 20.0 software measured all data, and SPSS 22.0 software facilitated statistical analyses. Intragroup and intergroup correlation analyses employed paired t-tests and independent t-tests, with statistical significance set at P < .05.

RESULTS

The study sample was composed of 32 subjects with a mean age of 22.43 ± 1.6 and 9 were male. The analysis of changes of condylar position from virtual surgical planning to the immediate postoperative period showed that the maximum condylar displacement was 1.74 mm and the maximum angular change was 3.92°. The analysis of changes in condylar position from the immediate postoperative period to 1 year postoperatively showed no statistically significant changes for the same type of jaw deformity. But patients with Class II malocclusion exhibited distinct condylar displacement and rotation patterns compared to those with Class III malocclusion and mandibular deformity.

CONCLUSION AND RELEVANCE

The application of virtual surgical planning in orthognathic surgery ensures a high degree of consistency in achieving the desired condylar position. Moreover, no significant change in condylar position was observed after orthognathic surgery for the same type of jaw deformity. However, patients with Class II deformities exhibited a higher susceptibility to rotational displacement of the condyles compared to those with other types of jaw deformities.

Comprehensive 3-dimensional Positional and Morphological Analyses of Condyle and Glenoid Fossa in Patients with Skeletal Class II Malocclusion following Bimaxillary Orthognathic Surgery

This study aimed to comprehensively and quantitatively characterize 3-dimensional (3D) positional and morphological changes of the condyle and glenoid fossa in patients with skeletal Class II malocclusion treated with bimaxillary orthognathic surgery. Twenty eligible patients treated at our institution from January 2016 to December 2021 with more than 12 months of postoperative follow-up were retrospectively enrolled. Radiographic data of cone-beam computed tomography (CBCT) for each patient were collected at 3 stages: 1 week preoperatively (T0), immediately after surgery (T1), and at least 12 months postoperatively (T2). Positional changes, surface and volumetric alterations of condyle, and bone remodeling in glenoid fossa were measured and compared based on voxel- and surface registrations in visual 3D methods. Most patients exhibited a tendency for condyles to shift posteriorly, laterally, superiorly, and rotated outward, downward, and forward immediately after surgery. Posterior, medial, superior movement and outward, upward, and backward rotation of condyles were observed during follow-up (T1-T2). Bone resorption frequently occurred in the posterior area of condylar surfaces, while bone remodeling was more common in the anterior region of the glenoid fossa. Reduced volume of the condyle was found in most cases, which was not associated with the amount of mandibular advancement. Overall, the condyle and its corresponding glenoid fossa remained relatively stable during the follow-up. Our results reveal positional and morphological alterations in the condyle and the glenoid fossa after bimaxillary orthognathic surgery in patients with skeletal class II malocclusion. These changes predominantly fall within the spectrum of physical adaption.

The effect of tongue reduction for preventing adverse effects in patients undergoing class III orthognathic surgery: a three-dimensional comparative analysis

OBJECTIVES

This study aims to evaluate the potential benefits of combining tongue reduction with mandibular setback surgery in patients undergoing class III orthognathic surgery. Specifically, we investigated whether this combined approach reduced the risk of surgical relapse, condylar resorption, and airway space reduction by mitigating tongue pressure on the mandible.

MATERIAL AND METHODS

The study retrospectively enrolled patients who had undergone bilateral sagittal split ramus osteotomy (BSSRO) with at least 5 mm of setback and met the criteria of a body mass index > 20 kg/m2 and tongue volume > 100 mm3. The study included 20 patients with 10 in the tongue reduction group (TR, n = 10) and 10 in the BSSRO only group (SO, n = 10).

RESULTS

The volumetric changes of the total airway space were significantly different between the TR and SO groups (p = 0.028). However, no significant differences were observed in the condylar resorption and postoperative relapse between the groups (p = 0.927 and 0.913, respectively). The difference between the resorption of the anterior and posterior segments of the condyle was also statistically insignificant (p = 0.826). Postoperative counterclockwise rotation of the proximal segment only demonstrated a significant correlation with postoperative relapse (p = 0.048).

CONCLUSIONS

The reduction in tongue volume demonstrated a preventive effect on the reduction of the airway space after mandibular setback, although it did not yield statistical significance concerning surgical relapse and condylar volume. The counterclockwise rotation of the proximal segment might be responsible for the forward displacement of the distal segment and postoperative relapse. However, the clinical implications of this finding should be interpreted with caution owing to the limited sample size CLINICAL RELEVANCE: Tongue reduction could potentially serve as a preventive measure in preserving the airway space and might be beneficial in mitigating the risk of obstructive sleep apnea in patients with class III deformity.