Adaptation of soft tissue following bilateral sagittal split ramus osteotomy in skeletal class III patients with facial asymmetry: A retrospective study.

PURPOSE: This retrospective study aimed to evaluate sequential changes in soft tissue thickness after bilateral sagittal split ramus osteotomy (BSSRO) in skeletal class III patients with facial asymmetry and to explore their correlation with surgical movements for optimal postoperative facial symmetry and esthetic outcomes. MATERIAL AND METHODS: This study included 37 patients with class III malocclusion and > 4 mm Menton (Me) deviation who underwent BSSRO. Posteroanterior cephalograms were captured at preoperative (T0), 6 weeks (T1), 6 months (T2), and 1 year (T3) postoperative intervals to analyze changes in Me deviation, fronto-ramal inclination (FRI), and soft tissue thickness. Statistical analysis was conducted to assess the changes in soft tissue thickness over time and the effects of surgical correction. RESULTS: Significant improvements in facial asymmetry were noted after surgery, with reductions in Me deviation and FRI on both the deviated side (DS) and non-deviated side (NDS). An increase in soft tissue thickness was observed on both the DS and NDS after surgery, with the NDS showing a continued increase between 6 months and 1 year, indicating an ongoing compensation for symmetry restoration. The study also identified a positive correlation between the surgical movement of the FRI and the increase in soft tissue width on the NDS after 6 months. CONCLUSION: This study established that soft tissue thickness continues to adapt and change up to 1 year after BSSRO, underscoring the need for a long-term evaluative approach in orthognathic surgery for patients with facial asymmetry.

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.

Redundancy of the Visual Identification of Lingula in the Bilateral Sagittal Split Ramal Osteotomy Procedure of the Mandible.

Introduction: The bilateral sagittal split ramus osteotomy (BSSRO) is the technique in vogue which is used for correction of a range of mandibular corpus deformity involving the dentoalveolar segment. The surgical technique has been subjected to a variety of modifications ever since its inception in the 1950s. One of the operative objectives which has been advocated sacrosanct has been the visual identification of lingula during the exposure of the medial aspect of the ramus. Materials and Method: BSSRO was successfully carried out in 45 cases operated over a period of eight years for correction of different kinds of skeletal mandibular deformity. The medial subperiosteal dissection did not involve a visual identification of the lingula. Conclusion: In our experience, the visual identification of the lingula is not essential to carry out a safe BSSRO procedure.

BSSRO Improves Mandibular Morphology Mainly through Correction of Body Length and Volume in Patients with Asymmetric Mandibular Prognathism.

Purpose: The purpose of this study is to analyze the change and stability of mandibular morphology in patients with asymmetric mandibular prognathism after bilateral sagittal split ramus osteotomy (BSSRO). Methods: We retrospectively analyzed fifty patients with asymmetric mandibular prognathism from the West China Hospital of Stomatology, Sichuan University, between January 2018 to March 2021. The spiral CT data before surgery, within two weeks after surgery, and at more than six months after surgery of each patient were collected. According to the deflection direction of the chin, the bilateral mandibles were defined as the long side and the short side. The morphological data of the bilateral condyle, the mandibular ramus, and the mandibular body were analyzed to determine the effect and stability of BSSRO on asymmetric mandibular prognathism. Results: It was found that the long-side mandible had greater condylar volume and diameter, mandibular ramus height and volume, and mandibular body length and volume (p < 0.05) before surgery. After surgery, the volume of the mandibular ramus increased, while the length and volume of the mandibular body decreased (p < 0.05) at the long side of the mandible; the morphological changes of the mandibular ramus and body at the short side of the mandible were not statistically significant (p > 0.05). When comparing the long and short sides of the mandible, the long side still had greater height and volume of the mandibular ramus (p < 0.01). The volume difference of the mandibular body from the two sides was corrected (p > 0.05), and the length difference of the mandibular body from the two sides was overcorrected (p < 0.05). At more than six months after surgery, the volume of the mandibular ramus and body increased, while their height decreased at the long side of the mandible (p < 0.05). For the other side, or the short side, the volume of the ramus and body increased, too. However, their height decreased (p < 0.01). Conclusion: The results of this study suggested good effect and stability of BSSRO on asymmetric mandibular prognathism, except for the correction of ramus height and volume.

Atypical Orthognathic Surgical Protocol for Facial Feminisation as an Adjunct to Gender Affirmation Therapy: a Case Report.

Gender Affirmation Surgery/Therapy (GAS/GAT) constitutes an array of surgical and hormonal therapy performed on patients presenting with a diagnosis of 'Gender Dysphoria'. Facial Feminisation Surgery is a part of the overall gender reassignment process. It is a broad term used to describe the surgical alteration, generally performed on a male-to-female transsexual individual, in which, a masculine facial appearance is changed to a more feminine form. An 18-year-old transgender male undergoing GAT reported to our centre in Mumbai, India with a complaint of masculine face with forwardly placed teeth in the upper arch and thick-set backwardly placed lower jaw and lip. Patient was taken up for ortho-surgical management to establish a feminine facial form and a stable functional occlusion. Mandibular advancement using the bilateral sagittal split ramus osteotomy, which is an uncommon protocol in GAT cases was found to be a viable option in the successful management of such a clinical scenario.

Is distal segment ostectomy essential for stabilization of the condylar position in patients with facial asymmetry?

BACKGROUND: The purpose of this retrospective study was to evaluate the postoperative change in the position and stability of the mandibular condyle after bilateral sagittal split ramus osteotomy (BSSRO) and BSSRO with distal segmental ostectomy (DSO) in patients with facial asymmetry using 3D computed tomography. METHODS: The condyles of the patient diagnosed with facial asymmetry were divided into the deviated side (DS) and the non-deviated side (NDS). Group I, which was treated with BSSRO only, and Group II, which additionally received DSO along with BSSRO, were superimposed on the condyle using the pre-and postoperative 3D CT. The amount of condylar change in anteroposterior displacement, mediolateral displacement, and rotation was measured. The clinical symptoms of temporomandibular joint were also evaluated before and after surgery for each patient. RESULTS: Between Groups I and II, there was no statistically significant difference in the anteroposterior condylar position on both DS and NDS. And also, there was no statistical difference between the two groups in the mediolateral change on DS but, statistically significant difference on NDS. The change in the rotation of the condyle was observed to rotate inward from both condylar heads of Groups I and II, and a statistically significant difference was observed between the two groups on both DS and NDS. Moreover, no difference in clinical temporomandibular joint symptoms was observed after surgery in each DS and NDS condyle of the two groups. CONCLUSIONS: As a result of analyzing the condylar position change of the group treated with BSSRO alone and the group treated with BSSRO and DSO in patients with facial asymmetry, there were statistically significant differences in the mediolateral displacement of NDS and the condyle rotation of NDS and DS. However, the anteroposterior condylar position did not show any difference in the bilateral condyles. In addition, since worsening clinical symptoms of bilateral temporomandibular joint were not observed before and after surgery in both groups, it is concluded that it is not necessary to accompany DSO in patients with facial asymmetry (minimum 3 mm, maximum 7 mm).

Posterior bending osteotomy: An effective measure to secure facial symmetry in orthognathic surgery.

This study aimed to compare the effectiveness of posterior bending osteotomy and grinding techniques for orthognathic surgery in patients with facial asymmetry. Patients who had undergone Le Fort I osteotomy and bilateral sagittal split ramus osteotomy, and who presented with a menton shift and setback difference exceeding 4 mm, were enrolled. Cone-beam computed tomography was performed before surgery (T0), immediately after surgery (T1), and 6 months after surgery (T2). Overall, 38 patients were included and divided into posterior bending osteotomy (n = 23) and grinding (n = 15) groups. Significant differences were observed between the posterior bending osteotomy and grinding groups on the treated side. In the grinding group, the gonion on the treated side was displaced slightly outward, resulting in a significant difference between both sides (non-treated side: 50.52 ± 4.20 [T0] and 48.67 ± 4.37 [T2]; treated side: 50.88 ± 4.55 [T0] and 51.00 ± 3.95 [T2]; p = 0.038). In the posterior bending osteotomy group, bilateral inward movements of the gonion were observed, and the distance from the midsagittal plane to the gonion did not differ significantly between the sides (non-treated side: 46.74 ± 4.41 [T0] and 45.54 ± 3.95 [T2]; treated side: 47.43 ± 4.93 [T0] and 45.18 ± 3.52 [T2]; p = 0.224). The yawing movement of the proximal segment was greater in the grinding group than in the posterior bending osteotomy group (non-treated side: p = 0.839; treated side: p = 0.025). Posterior bending osteotomy is recommended over the grinding method for patients with severe facial asymmetry, in order to ensure a symmetric and esthetic facial profile by allowing passive adaptation between the mandibular segments.

Effect of Mandibular Advancement Surgery on Tongue Length and Height and Its Correlation with Upper Airway Dimensions.

INTRODUCTION: The spatial position and dimensions of oral and pharyngeal soft tissues change post-mandibular advancement (MA) surgery which involves changes in position of soft palate, tongue and associated musculature. There is no study which simultaneously evaluates changes in tongue length and height post-MA surgery and correlates these changes with changes in upper airway dimensions and the amount of MA. MATERIALS AND METHODS: Treatment records of 18 patients that underwent MA with bilateral sagittal split ramus osteotomy were evaluated at T1 (01 week before surgery) and T2 (06 months post-surgery). Linear airway and tongue measurements were done on lateral cephalogram. Mean volume and mean pharyngeal area values were recorded from the acoustic pharyngometry (AP) records of patients. RESULTS: A statistically significant increase in tongue length (P value < 0.001) and nonsignificant change in tongue height were observed at T2 (P value > 0.05). A statistically significant increase in airway parameters recorded on both lateral cephalogram and AP was observed at T2 (P value < 0.001). Correlation analysis did not show a statistically significant correlation of change in tongue length and tongue height at T2 with the amount of MA, change in airway parameters on lateral cephalogram and AP (P value > 0.05). CONCLUSIONS: Mandibular advancement surgery is a viable option for improvement in pharyngeal airway in skeletal Class II patients with retrognathic mandible. Changes in tongue length observed in our study may correspond to the stretch of protruders of tongue, especially genioglossus, and may point toward possible relapse on a long-term follow-up.

The quantitative correlation between condylar resorption and skeletal relapse following mandibular advancement in skeletal class II malocclusion patients.

OBJECTIVE: The purpose of this study was to analyze the quantitative correlation between condylar resorption and skeletal relapse after mandibular advancement surgery. MATERIALS AND METHODS: Skeletal Class II malocclusion patients who underwent bilateral sagittal split ramus osteotomy (BSSRO) were included. Three-dimensional reconstruction was based on one-week and one-year post-operative CT scans. The condylar morphological alterations were assessed by anterior-posterior, medial-lateral diameter and condylar height. The mandibular relapse was calculated by the positional changes of pogonion, menton, gonions, gnathion and mental foramens. All data were measured by MIMICS and analyzed by SPSS software; significance was set at p<0.05. RESULTS: 31 patients (62 condyles) were enrolled into this study. 28 of 62 condyles showed resorption beyond 1 mm on condylar height and 15 were beyond 2 mm. Positional changes of chin, mental foramens and gonion were respectively 1.57 ± 2.36 mm, 1.31 ± 1.23 mm and 1.42 ± 1.02 mm. 21 of 31 patients experienced mandibular relapse less than 1 mm but additional 4 patients showing relapse more than 2 mm. Correlation with moderate intensity could be observed between condylar height alteration and post-operative mandibular displacement more than 1 mm (p = 0.035). CONCLUSION: The resorption degree of condylar height can be regarded as a useful parameter for evaluating post-operative skeletal relapse.

Transverse Changes in Mandible Following Bilateral Sagittal Split Ramus Osteotomy Advancement.

BACKGROUND: BSSRO is the most frequently performed surgical procedure for mandibular advancement. However, the effect of advancement on proximal segment is not clearly understood. AIM AND OBJECTIVES: The aim of the study was to evaluate the radiographic transverse changes in mandible following BSSRO advancement and to compare the amount of transverse displacement of the proximal segment with the amount of surgical advancement. MATERIALS AND METHODS: Twelve cases of skeletal class II deformity undergoing fixed orthodontic mechanotherapy and requiring mandibular advancement were selected for the study. Pre-operative (T0) PA ceph and OPG were used to measure the linear distances from right to left Co-Go, Go-Me, Go-Go, Co-Co, Rp-Rp and Co-Me points. The cases were operated for BSSRO mandibular advancement. Post-operative (T1) PA ceph and OPG were used to compare the changes in linear measurements. RESULT: There were six male and six female patients with an average age of 19.5 years. The average mandibular advancement was 6.5 mm. Post-operative radiographic changes in transverse measurements of Go-Me, Go-Go, Co-Co, Rp-Rp and Co-Me were statistical significant. The changes in Co-Go measurements were statistically not significant. We could not establish any correlation between mandibular advancement and amount of transverse changes. CONCLUSION: Significant changes were noticed in transverse dimensions of mandible following BSSRO advancement in both PA ceph and OPG. The transverse changes had no clinical implication during the post-operative follow-up.

Biomechanical comparison of temporomandibular joints after orthognathic surgery before and after design optimization.

The aim of this study is to analyse the biomechanical effects of bilateral sagittal split ramus osteotomy (BSSRO) on temporomandibular joints (TMJs) of a patient with mandibular prognathism. Two three-dimensional models of the maxilla, mandible, and articular disc were constructed based on pre- and postoperative cone-beam computed tomography (CBCT) images of the patient's head. Meanwhile, based on the preoperative model, numerical surgery of BSSRO was performed to predict the optimized postoperative model (named Num-post). Contact elements were used to simulate the interactions between the discs and articular cartilages and between the upper and lower dentitions. Muscle forces and boundary conditions corresponding to centric occlusion were applied on the models. Stresses on the disc, condylar, and temporal cartilages were significantly reduced after the optimized numerical surgery. Meanwhile, the stress distributions in the TMJ in the Num-post-operative model were uniform without stress concentration compared to Pre-operative model and Post-operative model, which suggests that the optimized numerical surgery can be beneficial to orthognathic surgeries.

Influence of temporomandibular joint disc displacement on mandibular advancement in patients without pre-treatment condylar resorption.

The purpose of this study was to clarify the correlation between pre-treatment anterior disc displacement and mandibular stability after orthognathic and orthodontic treatment among patients with a skeletal class II malocclusion and without pre-treatment condylar resorption. Thirty-seven patients were included (7 male, 30 female). The mean length of follow-up was 6.76±3.06 years. Patients with condylar resorption before treatment were excluded. Magnetic resonance images and lateral cephalometric radiographs were taken before treatment (T0), after treatment (T1), and at follow-up (T2). Patients were classified according to the degree of disc displacement: -10-10° 'normal', 11-50° 'slight to mild', ≥51° 'moderate to severe'. Results showed the condyle moved posterosuperiorly after treatment, and then moved anteriorly to a more concentric location during the long follow-up period. Condylar movement was found not to correlate with disc displacement. The degree of disc displacement before treatment did not correlate with the post-surgical mandibular positional change in either the sagittal or vertical direction. To conclude, the mandibular bilateral sagittal split ramus osteotomy was stable in the long-term after orthognathic and orthodontic treatment. In the absence of pre-treatment condylar resorption, the degree of initial anterior disc displacement did not have a significant influence on the stability of mandibular advancement.

Minimizing Relapse in Mandibular Asymmetry Correction by BSSRO with Intentional Osteotomy of Distal Segment: A Prospective Study.

INTRODUCTION: Surgical correction of the patients with mandibular asymmetry by bilateral sagittal split ramus osteotomy (BSSRO) creats remarkable results in the immediate post operative period, but it carries a high risk of relapse by powerful muscle forces and the osteotomized segments. To minimize this risk, literatures highlight the procedure of an intentional osteotomy and stripping of muscles. A prospective study was conducted in Government Dental College, Kottayam, Kerala, to assess the effect of intentional osteotomy of posterior part of distal segment and stripping of medial pterygoid muscle on the proximal segment on affected side in mandibular asymmetry patients treated with BSSRO. MATERIALS AND METHODS: 20 patients above 18 years with mandibular asymmetry underwent surgical correction by BSSRO setback and rotation. Clinical evaluation and postero anterior cephalogram (PA Ceph) were used to assess relapse. PA cephalogram taken post operatively at 2 weeks, 6 months and 1year were compared using cephalometric parameters by Grummons analysis to assess relapse. Paired t test and Chi-square test was used to analyse quantitative and qualitative parameters respectively with statistical significance of p < 0.05. RESULTS: Barring Methodological errors which is inevitable, the amount of relapse was not statistically significant with respect to dental midline, chin midline and frontal photograph. CONCLUSION: Intentional osteotomy of posterior part of distal segment and stripping of medial pterygoid muscle on the affected side can prevent relapse in patients who underwent surgical correction of mandibular asymmetry by BSSRO set back and rotation.

Effect of surgical mandibular advancement on pharyngeal airway dimensions: a three-dimensional computed tomography study.

The aim of this study was to quantify the changes in pharyngeal airway space (PAS) in patients with a skeletal class II malocclusion managed by bilateral sagittal split ramus osteotomy for mandibular advancement, using three-dimensional (3D) registration. The sample comprised 16 patients (mean age 21.69±2.80 years). Preoperative (T0) and postoperative (T1) computed tomography scans were recorded. Linear, cross-sectional area (CSA), and volumetric parameters of the velopharynx, oropharynx, and hypopharynx were evaluated. Parameters were compared with paired samples t-tests. Highly significant changes in dimension were measured in both sagittal and transverse planes (P<0.001). CSA measurements increased significantly between T0 and T1 (P<0.001). A significant increase in PAS volume was found at T1 compared with T0 (P<0.001). The changes in PAS were quantified using 3D reconstruction. Along the sagittal and transverse planes, the greatest increase was seen in the oropharynx (12.16% and 11.50%, respectively), followed by hypopharynx (11.00% and 9.07%) and velopharynx (8.97% and 6.73%). CSA increased by 41.69%, 34.56%, and 28.81% in the oropharynx, hypopharynx, and velopharynx, respectively. The volumetric increase was greatest in the oropharynx (49.79%) and least in the velopharynx (38.92%). These established quantifications may act as a useful guide for clinicians in the field of dental sleep medicine.

Three-dimensional analysis of postoperative returning movement of perioperative condylar displacement after bilateral sagittal split ramus osteotomy for mandibular setback with different fixation methods.

This study aimed to evaluate postoperative returning movement of perioperative condylar displacement after bilateral sagittal split ramus osteotomy (BSSRO) depending on a fixation method using three-dimensional (3D) analysis of computed tomography (CT). Twenty-five mandibular prognathic patients (50 condyles) who underwent orthognathic surgery with BSSRO were divided into three groups depending on the fixation method, which consisted of miniplate only (Group A), combined with single bicortical screw (Group B), or with more than one bicortical screw (Group C). CT data taken before, immediately after, and 3 to 6 months after surgery were analyzed. The condyle exhibited mainly lateral bodily displacement and inward and inferior rotation immediately after surgery. The amount of perioperative lateral displacement of the condyle increased according to the increasing number of fixation screws, but the mean displacements were not significantly different among the three groups. During the postoperative follow-up period, the amount of medial returning of the condyle was 102.2% of the intraoperative lateral displacement in Group A. In contrast, Group B and C exhibited partial returning movement by 71.3% and 38.9% of cases, respectively. In conclusion, stronger rigid internal fixation in orthognathic surgery using BSSRO is associated with reduced flexibility of postoperative functional adjustment of displaced condyle to the preoperative condylar position.