The role of a posteriorly inclined condylar neck in condylar resorption after orthognathic surgery (2023)

Several systematic reviews have been published on the effects of mandibular surgery on condylar remodeling without reaching a consensus. The purpose of this systematic review of systematic reviews was to assess the impact of mandibular advancement or bimaxillary surgeries on condylar resorption.

A literature search, using several electronic databases, was carried out by two reviewers independently. Article preselection was based on titles and abstracts, and final article selection based on full-text analysis of preselected studies. After final study selection, the quality of studies was assessed using the AMSTAR 2 tool. A decision algorithm was subsequently established to choose the best body of evidence.

From an initial yield of 1′848 articles, 23 systematic reviews were identified for further analysis, with ten studies being included in the final selection. Despite the generally low quality of the reviews, certain associations could be made: young patients, female patients, and those with a high mandibular plane angle are more prone to condylar resorption following mandibular advancement osteotomies, especially if anterior rotation of the mandible is performed during surgery. Patients undergoing bimaxillary surgery also appear to have a higher risk of developing condylar resorption.

In conclusion, these results confirm the multi-factorial nature of condylar resorption, stressing the need for well-controlled prospective studies with long-term follow-up to clearly identify potential risk factors associated with orthognathic surgery.

This study aimed to evaluate the condylar position changes in 12 months after bilateral sagittal split ramus osteotomy (BSSO) with and without a Le Fort I osteotomy in patients with Class III malocclusion and the influence of the 2 surgical approaches on the condylar position.

In this prospective cohort study, patients with skeletal Class III malocclusion who underwent orthognathic surgery between 2017 and 2019 were included. The main predictive variable is the effect of increasing Le Fort I osteotomy on condyle position, which is divided into BSSO-only group and BSSO+Le Fort I osteotomy group. The main outcome variables were the displacement of the condylar head and the rotation/inclination of the condylar long axis before and after surgery. Other study variables were according to the degree of asymmetry of the left and right side of the mandible, the measured values of both sides were divided into mandibular deviation and nondeviation. The cone-beam volumetric imaging images were obtained before surgery (T1) and immediately after surgery (T2), 3 months (T3), 6 months (T4), and 12 months (T5) after surgery by computerized tomography (CT). One-way ANOVA and Tukey test was used for correlation analysis. The p-value is set to 0.05.

Twenty-four adult patients diagnosed with skeletal Class III malocclusion were included in this study, 12 patients (male/female=6:6, mean age 21.8 years) who underwent BSSO+Le Fort I osteotomy and 12 patients (male/female=6:6, mean age 19.8 years) who underwent BSSO-only. The position of the bilateral condylar head in both surgery groups was adjusted continuously during the 12 months after the operation. Immediately and 12 months after surgery, both sides of the condylar long axis in the BSSO with Le Fort I osteotomy group and the BSSO-only surgery group rotated inward, tilted forward, and tilted inward. In the BSSO with Le Fort I osteotomy group, the rotation and tilt angle changes of the condylar long axis on both sides were stable 6 months after surgery.

The addition of Le Fort I osteotomy did not significantly change the rotation and tilt direction of the condylar long axis and could accelerate the stability of the condylar long axis after BSSO surgery.

This study aimed to assess mandibular morphologic changes to the condyle, ramus, mandibular body, and inferior mandibular border defect after sagittal split ramus osteotomy in class II and III patients.

The relationships among the condyle, ramus, and mandibular body measured by computed tomography preoperatively and postoperatively were assessed and factors related to the reduction of the condylar square and mandibular inferior border defect were examined.

Patients included 72 female patients with jaw deformity (36 skeletal class II cases, 36 skeletal class III cases). Postoperative reduction of the condylar square was significantly correlated with preoperative condylar height in patients with class II (P=.0297) vs preoperative condylar height and preoperative mandibular height in patients with class III (P < .0001). A mandibular inferior border defect was found in 18 of 72 class II sides (25.0%) and was significantly related to the position of the osteotomy line and attachment side of the inferior border cortex (P < .0001).

This study's findings suggest that the postoperative reduction of the condyle could be associated with preoperative condylar height. However, the mandibular inferior border defect in class II advancement surgery could be independently associated with technical factors in sagittal split ramus osteotomy.

This study was performed to evaluate the relationship between condylar height reduction and changes in condylar surface computed tomography (CT) values in jaw deformity patients following orthognathic surgery.

Mandibular advancement by sagittal split ramus osteotomy (SSRO) with Le Fort I osteotomy was performed in class II patients, and mandibular setback by SSRO with Le Fort I osteotomy was performed in class III patients. The maximum CT values (pixel values) at five points on the condylar surface and the condylar height, ramus height, condylar square, ramus angle, and gonial angle in the sagittal plane were measured preoperatively and 1 year postoperatively. Disc position was classified as anterior disc displacement (ADD) or other types by using magnetic resonance imaging (MRI).

Ninety-two condyles of 46 female patients were prepared for this study. Their temporomandibular joints (TMJs) were divided into two groups based on class (46 joints in class II and 46 joints in class III) and two groups based on the findings (25 joints with ADD and 67 joints with other findings). ADD with and without reduction was observed in two joints in the class III group and in 23 joints in the class II group. The distribution of ADD incidence had not changed 1 year after surgery. Condylar height decreased 1 year after surgery in both class II patients (mandibular advancement) (p < 0.0001) and class III patients (mandibular setback) (p = 0.0306). Similarly, condylar height decreased 1 year after surgery both in patients who showed ADD (p = 0.0087) and those with other types (p = 0.0023). Significant postoperative increases at all angle sites on the condylar surface were found in the class II (p < 0.05) and ADD (p < 0.05) groups.

This study showed that an enhanced condylar surface CT value might be one sign of condylar height reduction related to sequential condylar resorption, in combination with ADD.

This study evaluated whether presurgical characteristics, the magnitude of mandibular advancement, and changes in mandibular plane angle are correlated with long-term stability and postsurgical condylar remodeling and adaptations using 3-dimensional imaging.

Forty-two patients underwent bilateral sagittal split osteotomies for mandibular advancement using rigid fixation. Cone-beam computed tomography (CBCT) scans were acquired before surgery (T1), immediately after surgery (T2), and at long-term follow-up (T3). The average follow-up period was 5.3±1.7years after surgery. Anatomic landmark identification on the cone-beam computed tomographies and subsequent quantification of the changes from T1 to T2 and T2 to T3 were performed in ITK-SNAP (version 2.4; itksnap.org) and 3DSlicer (version 4.7; http://www.slicer.org) software. Surgical displacements, mandibular plane angle changes, and skeletal stability were measured relative to cranial base superimposition, whereas condylar remodeling was measured relative to regional condylar registration. Partial correlation coefficients were used to assess relationships between clinical and surgical variables, condylar remodeling, and long-term surgical relapse while controlling for variability in the length of follow-up.

B-point relapsed more than 2mm posteriorly in 55% of the patients. The only variables strongly associated with the posterior movement of B-point long-term were mesial yaw of the condyle during surgery (P≤0.01) and the length of follow-up from T2 to T3 (P≤0.01). There was no relationship between the magnitude of advancement or presurgical mandibular plane angle and relapse or condylar resorption. Condylar resorption was strongly associated with relapse of B-point in the posterior direction (P≤0.01) and clockwise rotation of the mandibular plane long-term (P≤0.01). Twenty-nine percent of subjects showed resorption of more than 2mm in the inferior direction at the lateral pole, and 17% of the subjects showed resorption of more than 2mm in the inferior direction at condylion. Compared with male subjects, females exhibited significantly greater condylar remodeling (P≤0.01) and slightly greater relapse at B-point (P≤0.05).

Surgical relapse at B-point may occur slowly over time and is primarily due to condylar resorption in mandibular advancement patients. Mesial yaw of the condyle during surgery may lead to condylar resorption postsurgically. In addition, females are at greater risk of condylar resorption postsurgically.

Anterior Disc Displacement without Reduction (ADDwoR) in adolescence can result in condylar resorption which produces mandibular retrusion/deviation (MR/D) in adulthood. This study aims to analyze the therapeutic effect of simultaneous genioplasty and temporomandibular joint (TMJ) anchorage surgery on ADDwoR with MR/D patients.

During 2016–2018, ADDwoR with MR/D cases were included and underwent TMJ anchorage surgery and genioplasty guided by digital design. Pre-/Post-surgical clinical manifestations, facial photography, radiographic data, facial shape satisfaction of clinicians/patients/third-party were recorded and analyzed.

A total of 32 cases (52 joints) were included. The average age was 24.09. Ratio of male/female was 4/28. Visual analog pain scale (VAS) score pre-/post-surgical ranged from 3 to 9 and 0–3, with an average of 6.03 and 1.18 (p<0.01). Maximal mouth opening pre-/post-surgical ranged from 16 to 33mm and 33–40mm, with an average of 22.43mm and 36.46mm (p<0.01). MRI was completed and showed stable disc reduction without recurrence 1 year postoperatively. MR/D was corrected and a better face shape was obtained. The satisfaction rate of clinicians, patients and third-parties was 92.375%, 94.156% and 94.218%, with an average of 93.583%.

For ADDwoR with MR/D patients, simultaneous TMJ anchorage surgery and genioplasty can improve TMJ symptoms/functions, correct facial appearance, and enhance the degree of satisfaction. The postoperative effect is stable, safe and reliable, which is worthy of clinical promotion.

To evaluate condylar changes 1 year after bimaxillary surgical advancement with or without articular disc repositioning using longitudinal quantitative measurements in 3-dimensional (3D) temporomandibular joint (TMJ) models.

Twenty-seven patients treated with maxillomandibular advancement (MMA) underwent cone-beam computed tomography before surgery, immediately after surgery, and at 1-year follow-up. All patients underwent magnetic resonance imaging before surgery to assess disc displacements. Ten patients without disc displacement received MMA only. Seventeen patients with articular disc displacement received MMA with simultaneous TMJ disc repositioning (MMA-Drep). Pre- and postsurgical 3D models were superimposed using a voxel-based registration on the cranial base.

The location, direction, and magnitude of condylar changes were displayed and quantified by graphic semitransparent overlays and 3D color-coded surface distance maps. Rotational condylar displacements were similar in the 2 groups. Immediately after surgery, condylar translational displacements of at least 1.5 mm occurred in a posterior, superior, or mediolateral direction in patients treated with MMA, whereas patients treated with MMA-Drep presented more marked anterior, inferior, and mediolateral condylar displacements. One year after surgery, more than half the patients in the 2 groups presented condylar resorptive changes of at least 1.5 mm. Patients treated with MMA-Drep presented condylar bone apposition of at least 1.5 mm at the superior surface in 26.4%, the anterior surface in 23.4%, the posterior surface in 29.4%, the medial surface in 5.9%, or the lateral surface in 38.2%, whereas bone apposition was not observed in patients treated with MMA.

One year after surgery, condylar resorptive changes greater than 1.5 mm were observed in the 2 groups. Articular disc repositioning facilitated bone apposition in localized condylar regions in patients treated with MMA-Drep.

The aim of this study was to evaluate the effect of the amount of setback movement and intraoperative clockwise rotation of the proximal segments on postoperative stability after orthognathic surgery to correct mandibular prognathism.

Thirty-six patients with mandibular prognathism who underwent orthognathic surgery with bilateral sagittal split ramus osteotomy were evaluated. The amount of postoperative relapse was analyzed using a cephalometric analysis.

Six months after surgery, the mean backward movement of the mandible at point B was 11.2mm, the mean intraoperative clockwise rotation of the proximal segment was 4.3° and the amount of postoperative relapse at point B was 2.3mm (20.3%) on average. The tendency of relapse did not significantly increase with the amount of setback but did increase significantly with the intraoperative clockwise rotation of the proximal segment.

This study suggested that postoperative relapse after mandibular setback surgery might be more related to the degree of the intraoperative clockwise movement of the proximal segment, rather than the amount of setback movement. When the amount of mandibular setback is considerable, postoperative relapse might be minimized with adequate control of the intraoperative positioning of the proximal segments.

To quantify the postoperative rotation of the proximal segments in 3D and to assess its role on skeletal relapse and condylar remodelling following BSSO advancement surgery.

56 patients with mandibular hypoplasia who underwent BSSO advancement surgery were enrolled into the study. A CBCT scan was acquired preoperatively, at one week postoperatively and at one year postoperatively. After segmentation of the facial skeleton and condyles, 3D cephalometry and condylar volume analysis were performed.

A mean mandibular advancement of 4.6mm was found. 55% of the condyles decreased in volume postoperatively, with a mean reduction of 6.1 volume-percent. Among 11 patients who exhibited a clinically significant relapse of more than 2mm, 10 patients exhibited a counterclockwise rotation of the proximal segments. The odds of skeletal relapse (>2mm) was 4.8 times higher in patients whose proximal segments were rotated in a counterclockwise direction. Postoperative flaring (3.3mm) and torque (0.3°) were, however, not associated with skeletal relapse or condylar remodelling.

Gender, preoperative condylar volume, postoperative condylar remodelling, counterclockwise rotation of the proximal segment and the amount of surgical advancement were prognostic factors for skeletal relapse (r²=0.83). The role of the mandibular plane angle in relapse is questionable.