Evaluation of Condylar Positional, Structural, and Volumetric Status in Class III Orthognathic Surgery Patients

Condylar volume comparison after rapid maxillary expansion by Haas and Hyrax in growing patients: A retrospective cross-sectional study

PURPOSE

This study aimed to evaluate the condylar volume of growing patients after rapid maxillary expansion (RME) by Haas and Hyrax appliances.

METHODS

This retrospective cross- sectional study assessed the records of patients diagnosed with transversal maxillary deficiency and with incomplete maturation of midpalatal suture. RME was performed with Haas or Hyrax appliances. Condylar volume was obtained by segmentation of DICOM images from cone-beam computerized tomographys before (T1) and after one year (T2) of RME. The results were compared between the experimental times, sex, and appliances by parametric tests (alpha=5%).

RESULTS

Twenty-seven patients were included (128±21 months old). There were no statistical differences in condylar volume between experimental times (T1 and T2), sex, and appliances to the right and left condyle (P>0.05).

CONCLUSION

RME by Haas or Hyrax does not impact the condylar volume of growing patients.

Effects of Mandibular Asymmetry Correction on Lateral Pterygoid Muscle Volume and Condylar Position: A Retrospective Study

This study aimed to assess alterations in lateral pterygoid muscle volume (LPMV) and condyle position after the correction of mandibular asymmetry by sagittal split ramus osteotomy (SSRO). The data were evaluated by superimposing cone-beam computed tomography (CBCT) images acquired before and after the SSRO. In total, 32 patients were divided into symmetric and asymmetric according to linear measurements from the dental midline. The study variables were lateral pterygoid muscle volume and condylar axial angle (CAA), and measurements were conducted using 3D Slicer software. The study's statistical analysis was performed using ANOVA, Kruskal-Wallis, and Bonferroni post hoc. LPMV exhibited a statistically significant increase in the control (Cs), deviation (Ds), and contralateral sides (CLs) (p = 0.001, 0.001, 0.001, respectively), with the greatest difference in change rate observed in the Ds (p < 0.01). CAA remained unchanged in the Cs (p = 0.147) and CLs (p = 0.509) but demonstrated increases in the Ds (p = 0.008). The study findings revealed significant changes in condyle position and LPMV following SSRO treatment. These alterations suggest a significant impact on the biomechanical environment of the temporomandibular joint and surrounding musculature. Such insights are crucial for understanding the functional outcomes and long-term stability of SSRO treatment in mandibular asymmetry patients.

Correlation between condylar repositioning, resorption, and mandibular relapse post-orthognathic surgery with the straight locking miniplate technique in patients with Class II and III malocclusion: a retrospective study

This study investigated the relationship between condylar position, condylar volume, and mandibular relapse following orthognathic surgery in which the proximal segments were temporarily fixed with a positioning device to maintain the condylar position. Computed tomography data (pre-surgery, immediately post-surgery, and 1 year post-surgery) from 12 patients with Class II malocclusion and 20 with Class III were analysed. Condylar volume was significantly lower in Class II patients than in Class III patients at all time-points (P < 0.001), and only Class II patients showed a significant volume reduction from immediately post-surgery to 1 year post-surgery (P < 0.001). Three-dimensional condylar movements from pre-surgery to immediately post-surgery and from pre-surgery to 1 year post-surgery were significantly greater in Class II patients than in Class III patients (both P < 0.001). Additionally, Class II patients exhibited more restoration movements to the preoperative position from immediately post-surgery to 1 year post-surgery, correlating with the volume reduction (r = -0.53, P = 0.007), which in turn correlated significantly with mandibular relapse (r = 0.63, P < 0.001). These findings suggest an association between preoperative volume, intraoperative movement, condyle movement restoration, volume reduction, and postoperative mandibular relapse, particularly in the Class II group. Accurate condylar positioning appears crucial for mitigating mandibular relapse in Class II cases.

Position and Dimensions of the Mandibular Condyle in Various Anterior-Posterior Skeletal Patterns: A CBCT Imaging Study in a Sample of Iranian People

Purpose: The aim of this comparative observational study is to evaluate and compare the size and position of the condyle among male and female patients with different skeletal patterns in the anterior-posterior dimension using cone beam computed tomography (CBCT) images. Materials and Methods: CBCT images of 120 patients, all prepared for other treatment purposes under the same conditions, were included in the study. The patients were classified into three groups-class I, class II, and class III-based on ANB angles and Wits analysis. The size of the condyle was measured in terms of width, height, and length. The position of the condyle was assessed by measuring the superior joint space (SS), anterior joint space (AS), and posterior joint space (PS) on the right and left sides separately. The measurements and results were analyzed using analysis of covariance (ANCOVA) and Bonferroni analysis. A statistical significance level of p  < 0.05 was considered. Results: The study found no statistically significant differences in the size of the SS and AS (p = 0.481 and p = 0.392, respectively) across different skeletal patterns. However, the size of the PS was significantly greater in class I subjects compared to class III subjects (p = 0.015). There were no statistically significant differences in condyle height and width among the different skeletal patterns (p = 0.367 and p = 0.720, respectively). In contrast, condyle length was statistically significant in class II individuals (p = 0.002) and was the lowest among the other skeletal pattern groups. Conclusions: Based on the results obtained, class I individuals have lower PS values compared to class III individuals. Additionally, class II individuals have shorter condyle lengths compared to those in class III and class I.

Assessment of mandibular bony healing, mandibular condyle and angulus after orthognathic surgery using fractal dimension method

BACKGROUND

This study aims to compare the trabeculation changes in the bone structure observed at the mandibular osteotomy line and the mandibular condyle in patients after single and double-jaw orthognathic surgery.

MATERIAL AND METHODS

The study included 38 patients (23 female, 15 male) who underwent mandibular surgery with bilateral sagittal split ramus osteotomy technique. The patients were divided into two groups according to their surgical operation: single-jaw (bilateral sagittal split ramus osteotomy) or double-jaw (Le Fort I osteotomy and bilateral sagittal split ramus osteotomy) surgery. Trabecular changes seen in mandibular osteotomy lines, mandibular condyle and mandibular angulus were evaluated on panoramic radiographs of patients (preoperative, postoperative 2nd day, postoperative 3rd month and 12th month) using fractal analysis method. Fractal dimension analysis was calculated by box counting method.

RESULTS

No statistically significant difference was found between the fractal analysis values in the mandibular condyle and angulus region preoperatively, postoperative 2nd day, postoperative 3rd month and postoperative 12th month in the single jaw group. There was no statistically significant difference between the fractal analysis values in the mandibular condyle and angulus region preoperatively, postoperative 2nd day, postoperative 3rd month and postoperative 12th month in the double jaw group. A significant difference was found in fractal analysis values in osteotomy lines in both groups. The lowest value was found on the 2nd postoperative day and reached the preoperative values in the 3rd and 12th months postoperatively. Fractal analysis values didn't show significant difference between the single, double-jaw groups in all periods.

CONCLUSIONS

This result suggests that the fractal analysis method can be used to evaluate trabeculation in the bone healing process of the osteotomy lines and indirectly affected areas in the postoperative period after orthognathic surgery.

Evaluation of mandibular condyle position in Class III patients after bimaxillary orthognathic surgery: A cone-beam computed tomography study

Objective

This retrospective study evaluated the mandibular condyle position before and after bimaxillary orthognathic surgery performed with the mandibular condyle positioned manually in patients with mandibular prognathism using cone-beam computed tomography.

Methods

Overall, 88 mandibular condyles from 44 adult patients (20 female and 24 male) diagnosed with mandibular prognathism due to skeletal Class III malocclusion who underwent bilateral sagittal split ramus osteotomy (BSSRO) and Le Fort I performed using the manual condyle positioning method were included. Cone-beam computed tomography images obtained 1-2 weeks before (T0) and approximately 6 months after (T1) surgery were analyzed in three planes using 3D Slicer software. Statistical significance was set at P < 0.05 level.

Results

Significant inward rotation of the left mandibular condyle and significant outward rotation of the right mandibular condyle were observed in the axial and coronal planes (P < 0.05). The positions of the right and left condyles in the sagittal plane and the distance between the most medial points of the condyles in the coronal plane did not differ significantly (P > 0.05).

Conclusions

While the change in the sagittal plane can be maintained as before surgery with manual positioning during the BSSRO procedure, significant inward and outward rotation was observed in the axial and coronal planes, respectively, even in the absence of concomitant temporomandibular joint disorder before or after the operation. Further long-term studies are needed to correlate these findings with possible clinical consequences.

Volumetric changes in temporomandibular joint space following trans-oral vertical ramus osteotomy in patients with mandibular prognathism: a one-year follow-up study

This study measured and analyzed chronological changes in temporomandibular joint space volume by compartment following transoral vertical ramus osteotomy (TOVRO) using reconstructed 3-dimensional (3D) images of patients with mandibular prognathism. It included 70 joints of 35 patients who underwent TOVRO between January 2018 and December 2021. Computed tomography (CT) or cone-beam CT (CBCT) was performed before surgery (T0) and at 3 days (T1), 6 months (T2), and 12 months postoperatively (T3). These scans were then analyzed using 3D software. The volumes of the overall (Vjs), anterior (Vajs), posterior (Vpjs), medial (Vmjs), and lateral (Vljs) joint spaces were calculated at each time point. A linear mixed model and repeated-measures covariance pattern with unstructured covariance were used to evaluate significant changes in joint space volume over time. Vjs significantly increased to 134.54 ± 34.28 mm3 at T3 compared to T0 (p < 0.001). Vpjas and Vljs increased by 130.72 ± 10.07 mm3 and 109.98 ± 7.52 mm3 at T3 compared to T0, respectively (p < 0.001). However, no significant difference was observed between T0 and T2 in Vajs and Vmjs (p = 0.9999). The observed volume increases in Vpjs and Vljs appeared to contribute to the overall Vjs increase.

Condylar Positional Changes in Skeletal Class II and Class III Malocclusions after Bimaxillary Orthognathic Surgery

Orthognathic surgery is indicated to modify the position of the maxillomandibular structure; changes in the mandibular position after osteotomy can be related to changes in the position of the mandibular condyle in the articular fossa. The aim of this study was to determine changes produced in the mandibular condyle 6 months after orthognathic surgery. A cross-sectional study was conducted that included subjects who had undergone bimaxillary orthognathic surgery to treat dentofacial deformity of Angle class II (group CII) or Angle class III (group CIII). Standardized images were taken using cone-beam computed tomography 21 days before surgery and 6 months after surgery; measurement scales were used to identify the condylar position and its relations with the anterior, superior, and posterior joint spaces. The results were analyzed using the Shapiro-Wilk and Student's t-tests, while considering a value of p < 0.05 as indicating a significant difference. Fifty-two joints from 26 patients, with an average age of 27.9 years (±10.81), were analyzed. All subjects in both group CII and group CIII showed a significant change in the anterior, superior, and posterior joint spaces. However, postoperative changes in the position of the condyle in the articular fossa were not significant in the anteroposterior analysis. We conclude that orthognathic surgery causes changes in the sagittal position of the mandibular condyle in subjects with mandibular retrognathism and prognathism.

Artificial Intelligence Splint in Orthognathic Surgery for Skeletal Class III Malocclusion: Design and Application

BACKGROUND

Digital splints are indispensable in orthognathic surgery. However, the present design process of splints is time-consuming and has low reproducibility. To solve these problems, an algorithm for artificial intelligent splints has been developed in this study, making the automatic design of splints accessible.

METHODS

Firstly, the algorithm and program of the artificial intelligence splint were created. Then a total of 54 patients with skeletal class III malocclusion were included in this study from 2018 to 2020. Pre and postoperative radiographic examinations were performed. The cephalometric measurements were recorded and the difference between virtual simulation and postoperative images was measured. The time cost and differences between artificial intelligent splints and digital splints were analyzed through both model surgery and radiographic images.

RESULTS

The results showed that the efficiency of designing splints is significantly improved. And the mean difference between artificial intelligent splints and digital splints was <0.15 mm in model surgery. Meanwhile, there was no significant difference between the artificial intelligent splints and digital splints in radiological image analysis.

CONCLUSIONS

In conclusion, compared with digital splints, artificial intelligent splints could save time for preoperative design while ensuring accuracy. The authors believed that it is conducive to the presurgical design of orthognathic surgery.

[Three-dimensional assessment of positional changes of the mandibular condyles following orthognathic surgery]

THE AIM THE STUDY

This study aims to assess the postoperative condylar displacement after orthognathic surgery using three-dimensional analysis of computed tomography.

MATERIAL AND METHODS

This retrospective study included 64 condyles from 32 patients with skeletal Class II (Group 1, n=16) and III (Group 2, n=16) deformities. All patients underwent a bimaxillary surgery. The three-dimensional CT images were evaluated to assess condylar displacement.

RESULTS

The condyle exhibited mainly superior and lateral torque immediately after surgery. Posterior displaced condyles were found in two cases in group 1 (Class II malocclusion).

CONCLUSION

The present study found the condyle displacement that can be mistaken as posterior displacement of condyle in analysis of sagittal sections of CT scans.

Changes in the condylar head after orthognathic surgery in Class III patients: a retrospective three-dimensional study

OBJECTIVES

To evaluate the axial and dimensional changes of the condylar head after orthognathic surgery, including Le Fort I and bilateral sagittal split ramus osteotomies, and to assess condylar remodeling through three-dimensional (3D) surface superimposition.

MATERIALS AND METHODS

Twenty-four patients (15 females, 9 males; mean age: 32.22 ± 6.92 years) with skeletal Class III deformity were included in the study. Cone-beam computed tomography data obtained in the preoperative (T0) and postoperative (T1) periods were examined using Mimics and 3-Matic software. The height, depth, and width of the condylar head and its angular changes were measured. The volumes of the 3D reconstructed models were calculated, and remodeling amounts were evaluated through regional surface superimposition. Statistical significance was set at P < .05.

RESULTS

Following the surgery, there was a significant decrease in the size of condyles (P < .05). An inward rotation of the condyles was found in the axial plane (T0: 79.60 ± 6.01°, T1: 76.6 ± 6.48°, P < .05). The maximum resorption, maximum apposition, mean remodeling, and mean absolute remodeling were -2.63 ± 1.23 mm, 1.15 ± 0.4 mm, -0.30 ± 0.34 mm, and 0.73 ± 0.43 mm, respectively. No correlation was found between the angular changes and remodeling parameters or linear and volumetric changes of the condylar head (P > .05).

CONCLUSIONS

Condyles undergo a remodeling process with a resorptive character following orthognathic surgery, without clinically significant effects in the present study.

[Condylar displacement following orthognathic surgery]

The overview of the current literature in the research of mandibular condyle displacement after orthognathic surgeries was done. The correct postoperative mandibular condyle position is considered as one of the determinants of the stability of treatment results.