Mandibular Setback Research Articles

Validation of a Finite Element Model for Clinical and Virtual Evaluation of the Changes in Airway Dimensions Following Class III Bimaxillary Orthognathic Surgery.

The aim of this study was to evaluate pharyngeal airway changes in adult skeletal Class III cases whose bimaxillary surgical treatments were planned with different amounts of maxillary and mandibular movement using lateral cephalometric radiographs and finite element analysis (FEA). Our null hypothesis was that bimaxillary orthognathic surgery in which maxillary forward movement (MF) is greater than mandibular backward movement (MB) will result in more expansion of the pharyngeal airway. A total of 31 individuals (11 females, 20 males) with class III skeletal deformity were included in the study. Patients who underwent bimaxillary orthognathic surgery with greater maxillary advancement (MF > MB) were categorized in Group 1 (n = 15), and those with greater mandibular set-back (MB > MF) as Group 2 (n = 16). Changes in airway dimensions were evaluated from lateral cephalometric radiographs. In addition, FEA modeling was used to determine pharyngeal airway changes with 5 different MF/MB combinations performed in skeletal class III bimaxillary surgeries. Nasopharyngeal and oropharyngeal airway dimensions increased in direct proportion to the amount of MF. Hypopharyngeal volume decreased compared to preoperative value in direct proportion to the decrease in MB. According to the FEA models, total pharyngeal airway volume decreased when MF was less than or equal to MB, was nearly unchanged when MF was 2mm greater than MB, and increased when MF was 4mm greater than MB. The results of FEA and lateral cephalometric analysis were compatible. Our results supported the null hypothesis. We concluded that when possible, planning slightly more maxillary advancement than mandibular set-back will not have an adverse impact on the airway. Although the skeletal deformity only causes forward displacement of the mandible, dividing the skeletal correction between the maxilla and mandible may be considered to avoid the risk to patients' quality of life in terms of respiratory function.

Three-Dimensional Change of Lip after Two-Jaw Surgery in Facial Asymmetry Using Facial Scanner

A facial scanner and three-dimensional computed tomography (CT) were used to evaluate the three-dimensional change in lip asymmetry before and after two-jaw surgery for 22 patients with facial asymmetry (menton deviation > 3 mm). We used the labrale superius (Ls), deviated/non-deviated-side cheilions (Ch-D/Ch-ND), and labrale inferius (Li) to construct the upper and lower lip planes to evaluate the lip asymmetry. A correlation analysis was performed to determine the factors related to the vertical change in the cheilions (ΔChZ-D/ND). In the transverse axis, Ch-D and Li moved to improve the asymmetry after surgery. All landmarks, except the Ls, moved backward in the anteroposterior axis. In the vertical axis, significant upward movement was observed in all hard tissue landmarks; however, there were no significant changes in the soft tissue. In the lip plane, the difference in the height of Ch-D and Ch-ND was significantly reduced (1.38 mm vs. 0.72 mm). In the anteroposterior axis, the ΔChZ-D/ND showed significant correlations with the mandibular setback. In the vertical axis, the ΔCh-ND showed significant correlations with the maxillary impaction of the non-deviated side. The improvement in lip asymmetry post-surgery was mainly achieved by the movement of the lower lip and Ch-D rather than the upper lip and Ch-ND.

Three-Dimensional Evaluation of Upper Airway Changes After Bimaxillary Surgery of Skeletal Class 3 Patients.

The aim of this study was to evaluate the 3-dimensional changes in upper airway space of class 3 patients after surgery with sleep-related breathing disturbance. This is a retrospective cohort study included 25 patients who had undergone bimaxillary orthognathic surgery with maxillary advancement and mandibular setback for skeletal class 3 deformity. The changes in minimum axial area, nasopharyngeal and oropharyngeal airway volume were determined by cone-beam computed tomography images, as well as the sleep parameters by polysomnography preoperatively and postoperatively. The impacts of mandibular setback and maxillary advancement amounts on the airway structures were evaluated and compared with other parameters. The results show that pharyngeal volume measurement means were found to be significantly increased postoperatively ( P <0.05). No significant difference was observed in the mean values of minimum axial area and sleep parameters after the operation ( P> 0.05). A positive relationship was determined between the oropharyngeal volume and minimum axial area changes at a rate of 60% ( r : 0.600). No relationship was revealed between airway volume changes and polysomnographic parameters. An increase in the total airway volume and no postoperative sleep-related disturbance symptoms were observed in the patients treated by maxillary advancement and mandibular setback surgery.

Comparison of Early Postoperative Neurosensory Testing After Mandibular Set-Back With the Inferior Alveolar Nerve in the Proximal Segment Versus the Distal Segment

The purpose of this study was to determine if there is a difference in postoperative neurosensory testing (NST) scores at 6 weeks following mandibular setback surgery between subjects that received a sagittal split osteotomy (SSO) with the inferior alveolar nerve (IAN) located in either the proximal segment (PS) or the distal segment (DS) following completion of split. It has been found that neuropraxia often results in a return to sensation within the first 4 weeks following the initial injury.1 The null hypothesis was that no significant difference exists in postoperative NST scores between subjects that had the IAN in the PS or DS.

Effect of Orthognathic Surgery on Movement of the Cheilion.

The cheilion (Ch), corner of the mouth, is the soft-tissue landmark where the upper and lower lips intersect. Orthognathic surgery can modify Ch position, which can affect facial esthetics. The aims were to evaluate Ch movements resulting from Le Fort I maxillary advancement with maxillary impaction or downgrafting, and with mandibular advancement or setback, and to investigate relationships between surgical movements and Ch movements. The 45 patients had undergone bilateral sagittal split ramus osteotomy with Le Fort I advancement surgery. They were divided into 4 groups according to surgical movement direction. Preoperative and postoperative photographs were calibrated. Standardized methods were used to identify and measure preoperative and postoperative Ch positions. Significant correlations were detected between extent of maxillary downgrafting and inferior movement of the Ch in group 1 ( r =0.988, P =0.001) and group 3 ( r =0.915, P =0.001). Also, significant correlations were detected between extent of mandibular advancement and anterior movement of the Ch in group 3 ( r =0.561, P =0.046) and group 4 ( r =0.661, P =0.005). The findings indicate that, in patients who undergo bilateral sagittal split ramus osteotomy/Le Fort I surgeries, mandibular advancement moves Ch anteriorly and maxillary downgrafting moves Ch inferiorly.

Soft Tissue Movement in Orthognathic Surgery: Does Pre-Operative Soft Tissue Thickness Affect Movement Change?

Background: The aim of this study was to examine whether the thickness of the preoperative soft tissue affects the degree of soft tissue movement relative to the hard tissue movement after orthognathic surgery. Methods: This is a retrospective examination of lateral cephalometric X-rays of patients who underwent orthognathic surgery in single medical center, during a 5-year period. Demographic and operative data were collected. Soft tissue thickness was measured in preoperative cephalometric X-ray, followed by superimposition of postoperative (&gt;6 months) cephalometric X-rays by overlapping fixed bony points. Results: In the upper jaw, there was a decrease in the relative movement of soft tissue with an increase in the initial thickness in surgeries performing advancements up to 5 mm (r = −0.288). In mandibular advancements, there was a clear decrease in soft tissue movement ratio with an increase in the initial soft tissue thickness (r = −0.418), while there was no correlation in mandibular setback cases (r = 0.062). The same correlation between the decrease in relative soft tissue movement and the increase in initial soft tissue thickness was found in advancement genioplasty (r = −0.411). Conclusion: This research shows a general pattern of decrease in relative movement of soft tissue in orthognathic surgery correlated to an increase in its initial thickness.

Three-Dimensional Quantitative Assessment of Condylar Displacement and Adaptive Remodeling in Asymmetrical Mandibular Prognathism Patients After Sagittal Split Ramus Osteotomy.

This study was performed to evaluate the condylar displacement and associated condylar remodeling in class III patients following mandibular setback surgery via sagittal split ramus osteotomy (SSRO). The sample comprised of 26 condyles of 13 subjects (mean age of 21.2±2.6y). We evaluated patients with mandibular prognathism and facial asymmetry who had undergone SSRO for mandibular setback at Korea University Hospital between January 2016 and December 2018. Three-dimensional segmentation of the mandibular condyles was done using the initial cone-beam computed tomography scan and scan taken 12 months postoperatively or later. Quantitative assessments of the 3-dimensional condylar displacement from T0 to T1 and bony remodeling of 8 regions of the condylar head were performed. The correlation between the condylar displacement and condylar head remodeling on the deviated (D) and nondeviated (ND) sides was analyzed. Significant correlations between condylar displacement and surface remodeling were observed in both D and ND condyles. The anteroposterior condylar displacement was significantly different between the D and ND sides (P=0.007). There was no significant difference in condylar remodeling between the 2 sides. Condylar displacement and adaptive remodeling after SSRO varied greatly among individuals. Compared with displacement in the ND condyle, displacement in the D condyle has a greater association with condylar remodeling in both D and ND condyles. There is no significant difference in condylar head remodeling between D and ND condyles.

Influence of different treatment procedures on the temporomandibular joint after mandibular setback in skeletal class III - A retrospective study

The aim of this study was to clarify the effects of three different orthognathic surgical procedures on the temporomandibular joint after mandibular setback. Conventional sagittal split ramus osteotomy (SSRO) with segmental fixation (conv-SSRO), intraoral vertical ramus osteotomy (IVRO), or SSRO without fixation followed by the physiological positioning strategy (nonfix-SSRO) was performed for mandibular setback. Temporomandibular joint disorder (TMD) symptoms were clinically assessed, and the condylar head angle was measured. In total, 129 patients participated. Preoperative TMD and treatment procedure were related to postoperative TMD. A menton deviation of 3.43 mm was the cutoff for the risk of postoperative TMD. The incidence rate of postoperative TMD in the conv-SSRO group was higher than that in the IVRO (p = 0.0197) and nonfix-SSRO (p = 0.0001) groups in asymmetric cases. There was no significant postoperative change in the temporomandibular joint space in each group. In symmetric and asymmetric cases, the condylar head was rotated inwards by 5.82 ± 4.75° (p < 0.0001) and 5.44 ± 3.10° (p < 0.0001), respectively, in the conv-SSRO group, and outwards by −7.98 ± 5.05° (p < 0.0001) and −8.32 ± 6.38° (p < 0.0001), respectively, in the IVRO group, but it was almost stable in the nonfix-SSRO group. Within the limitations of the study it seems that nonfix-SSRO should be preferred over conv-SSRO and IVRO whenever appropriate.

Clinical significance of postoperative skeletal relapse in the treatment of mandibular prognathism: Receiver operating characteristic curve analysis

Postoperative skeletal relapse is the most important issue in patients undergoing orthognathic surgery. This study aimed to investigate clinical skeletal relapse (≥2mm) after mandibular setback surgery (intraoral vertical ramus osteotomy: IVRO) using receiver operating characteristic curve (ROC curve) analysis. Serial cephalograms of 40 patients with mandibular prognathism were obtained at different time points: (1) before surgery (T1), (2) immediately after surgery (T2), and (3) at least with a 2-year follow-up postoperatively (T3). The menton (Me) was used as the landmark for measuring the amount of mandibular setback and postoperative skeletal relapse. Postoperative stability (T32) was divided into groups A and B by skeletal relapse ≥2mm and <2mm, respectively. The area under the ROC curve (AUC) was used to determine the cut-off point for mandibular setback. At the immediate surgical setback (T21), the amount of setback in group A (15.55mm) was significantly larger than in group B (10.97mm). Group A (T32) showed a significant relapse (4.07mm), while group B showed a significant posterior drift (1.23mm). The amount of setback had the highest AUC area (0.788). The cut-off point was 14.1mm (T21) that would lead to a clinical relapse of 2mm (T32). In IVRO, the postoperative mandibular positions reveal posterior drift and anterior displacement (relapse). The experience of clinical observation and patient perception of postoperative skeletal relapse was ≥2mm. In the ROC curve analysis, the cut-off point of setback was 14.1mm.

Comparison of short-term condylar positional changes in mandibular prognathism after surgery-first approach: Symmetric setback versus asymmetric setback

The aim of this study was to compare how the displacement of the mandibular condyle changed after symmetric or asymmetric mandibular setback surgery using the surgery-first approach (SFA). Patients who underwent mandibular setback surgery using the SFA were selected and divided into a symmetry group (n = 18) with differences of less than 2 mm between the right and left setback, and an asymmetry group (n = 18) with a difference of greater than 2 mm. Cone-beam computed tomography (CBCT)-generated cephalograms were obtained after three-dimensional superimposition of CBCT images taken before surgery (T0), within one week after surgery (T1), and seven months after surgery (T2). The condylar positions were measured. Condylar positional changes according to time were compared between the two groups and correlation analysis was performed. There were significant positional changes in mandibular condyles over time in both groups. However, most of these changes returned to their initial state. In the asymmetry group, there was a greater internal rotation of the mandibular condyle on the lesser setback side. The correlation analysis results revealed that only the setback difference was associated with rotational displacement of the condyle on the lesser setback side at two time points (T1-T0, T2-T0). In the SFA, significant condylar displacement occurred immediately after both symmetric and asymmetric mandibular setback surgery, and the right/left difference in mandibular setback showed a significant positive correlation with rotational displacement. Although more significant rotational displacement of the mandibular condyle was observed after asymmetric mandibular setback surgery, the amount was not large enough to be clinically significant.

Evaluation of Skeletal Changes after Mandibular Setback Surgery Using the NM-Low Z Plasty Technique in Skeletal Class III Patients.

The study's objective was to evaluate skeletal changes in 38 skeletal class III patients following mandibular setback surgery using NM-Low Z plasty. Thirty-eight skeletal class III patients (ANB angle lower than 0) who underwent the NM-Low Z plasty technique for surgical mandibular setback procedure at Thammasat University Hospital between January 2017 and March 2020 were included in the study: 29 patients had two jaw surgeries, and 9 patients had one jaw surgery. An additional 14 patients had genioplasty. Three lateral cephalograms were traced and digitized with Dolphin Imaging software: T0, T1, and T2. The distance between the B-point and the SN7 perpendicular line defined immediate changes after surgery (T1-T0) and stability after surgery (T2-T1). The reliability test included 6 cephalograms retraced after 2-week interval. At point B, the principal result was horizontal movement forward. The analysis used paired t-tests. The mean mandibular setback was 9.78 mm, and the mean skeletal relapse was 2.61 mm, or 26.69%. Statistical analysis showed postoperative differences (p < 0.05). Vertical measurement in B-SN7 reduced immediately and postoperatively. Postoperatively, the mandible relapsed significantly forward and upward. Rotational relapse is a concern with NM-Low Z plasty in hypo-/: normodivergent patients.

The Clinical and Radiographic Changes of Temporomandibular Joint (TMJ) Following Mandibular Set Back Surgery by Bilateral Sagittal Split Osteotomy (BSSO).

BackgroundBilateral Sagittal Split Osteotomy (BSSO) is one of the treatment options for Class III maxillary deficiency which may affect the condylar position and the patient’s occlusion. We aimed to evaluate the clinical and radiographic changes of temporomandibular joint (TMJ) following mandibular set back surgery by BSSO.MethodsIn this retrospective study, All Class III patients, aged between 18-30 years old who underwent bimaxillary orthognathic surgery in the Oral and Maxillofacial Surgery Ward of Ghaem Hospital, Mashhad, Iran from January 2018- January 2020 were enrolled. Radiographic changes of joint space, condylar position and clinical changes for maximal mouth opening and joint sound were examined before and 6 months after surgery. Data were analyzed by SPSS16 software and the significance level of the data was set at P-value < 0.05.ResultsTwenty-five patients were recruited. The axial angle of the left and right condyle and condylar inclination on both sides reduced but this reduction was not statistically significant. While the anterior joint space was reduced and posterior joint space was increased in both sides, the changes on the right side were only significant (P = 0.039). In clinical examinations maximum mouth opening, lateral and protrusive movements were also decreased but this reduction was not statistically significant.ConclusionThe mandibular set back with BSSO surgery in class III skeletal patients had no significant effect on the position of the condyle in the glenoid fossa as well as clinical symptoms.

Emergence from Anesthesia: A Comparison between Isolated Mandibular Setback and Bimaxillary Orthognathic Surgeries in Skeletal Class III Patients.

Background:We aimed to compare the emergence from anesthesia between the isolated mandibular setback and bimaxillary orthognathic surgeries in Skeletal Class III Patients.Methods:All healthy patients with skeletal class III deformity admitted to Mashhad Dental School, Mashhad, Iran from the years 2017 to 2018 were included in this study. They were candidates for either bimaxillary orthognathic surgery (Bimax surgery) through a combination of mandibular setback surgery plus maxillary advancement or isolated mandibular setback (Monomax surgery). The predictor variable was the type of jaw displacement and anesthesia duration, while the outcome variable was the duration of emergence from general anesthesia. The duration of emergence from anesthesia was calculated from the time the patient was transported to the recovery room until the time of safely discharging from the recovery room. For statistical analysis, the significance level was set at 0.05 using SPSS 21.Results:A total of 81 consecutive patients, comprising 45 (55.6%) males and 36 (44.4%) females, with an average age of 23.15±4.58 years were recruited. Among the participating patients, 56 (69.1%) underwent bimaxillary surgery while the other 25 (30.9%) were treated with Monomax surgery. Regardless of the type of performed surgery, the duration of general anesthesia was the only factor to be significantly correlated to the length of emergence from anesthesia (P= 0.001). Conclusion:Increased exposure time to general anesthesia might result in a longer emergence from anesthesia, despite the type of performed orthognathic surgery. Further clinical trials are needed to support the relevancy.

P-67892863-249 - Upper airway 3D assessment in CBCT-based orthognathic surgery

<h3>Objectives</h3> To stratify the maxilla-mandibular movements in the orthognathic surgery treatments of class III patients, assess the volumetric and bidimensional repercussions of these movements in the Upper Airway (UA). <h3>Methods</h3> The CBCT data of 44 patients class III, who had undergone orthognathic surgery were collected. After acquisition, the images were recorded and stored in Digital Imaging Communication in Medicine (DICOM) format. Preoperative files (T0) and the 1 to 4 months post-operative files (T1) were obtained. The 3D craniometric evaluation was carried out in the software. In the sinus/airway tool, the total airway pharyngeal nasopharynx, oropharynx, and hypopharynx were delineated, as following the boundaries. In each region, the volume, Minimum Axial Area (MAA) and the area of the respective delineated regions were calculated. The patients were divided into Group I (maxilla 0 to 4.9mm forward) and Group II (the maxilla 5.0 to 10.0mm forward). <h3>Results</h3> In Group I the correlation between the counterclockwise and the hipopharynx's MAA was moderate (0.439), and for every 1mm of maxillary advancement obtained a gain of 214.74mm³ in nasopharynx and 653.90mm³ in the oropharynx. <h3>Conclusion</h3> Maxillary advancement promotes an increase in the upper airway, compensating for a possible constriction that the mandibular setback may promote in the hypopharynx. Small maxillary advancements associated with different mandibular movements promoted greater airway gain.

Accuracy of Patient-specific Soft-tissue Prediction Algorithms for Maxillomandibular Surgery in Class III Patients.

Context:Improved esthetics is an important factor for most patients undergoing orthognathic surgery. Thus, a treatment simulation that can provide patients with a realistic view of the esthetic outcome after surgery is important in clinical practice.Aims:To evaluate the accuracy of simulations generated using algorithms specific for patient's type of malocclusion and surgical procedure compared to nonspecific algorithms.Settings and Design:A total of 36 patients (average age 18.41 years) who had undergone maxillary advancement and mandibular setback for Class III malocclusion were included.Subjects and Methods:The presurgical and postsurgical cone-beam computed tomography scans were used to generate the lateral cephalograms and the surgical simulations were created with the patient-specific algorithm (specific for Class III patients) and the nonspecific algorithm (default algorithm not specific for any particular malocclusion or type of surgery) using the treatment simulation feature in Dolphin Imaging software. The accuracy of the simulations was examined by comparing the soft-tissue changes in the surgical simulations with the postsurgical result.Statistical Analysis Used:Statistical analyses were performed with SPSS-software at 0.05 significance level. For the mean difference between the postsurgical and surgical-simulation landmarks, a paired sample t-test (Student's t-test) was performed.Results:Patient-specific algorithms were accurate in vertical prediction of lower lip, B’, tip of nose, upper lip, and horizontal prediction of pogonion’. Whereas the nonspecific algorithm was accurate in the horizontal prediction of the lower lip, pogonion’, and menton’.Conclusions:Patient-specific and nonspecific algorithms for generating surgical simulations showed different accuracy for vertical and horizontal predictions of the parameters.

Is There Any Differences in Dento-Skeletal Stability between One Vs. Three-Screw Fixation of Mandible Following Bilateral Sagittal Split Osteotomy (BSSO)?

Background:The aim of this study was to compare the dento-skeletal stability between one and three-screw fixation of mandible following bilateral sagittal split osteotomy (BSSO) in skeletal class 3 patients.Methods:Healthy patients with skeletal class 3 malocclusion in Mashhad, Iran, from August 2020 to May 2021 were undergone mandibular setback through bilateral sagittal split osteotomy. Rigid fixation was performed in one group with one-screw technique, and three-screw fixation was done in another group. Cephalogram x-rays were prepared and analyzed in three stages: before surgery (T0), one week after the surgery (T1), and six months postoperatively (T2). The linear and angular alterations of chosen multivariate skeletal and dental variables were evaluated and statistically compared in all three periods. Results:This study included a total of 20 patients, 12 of them were female (60%). Patients in the one-screw fixation group had a mean age of 20.6 ± 2.2 years old, whereas those in the three-screw fixation group were 21.5 ± 2.8 years old, with no statistically significant difference. Both groups had excellent mandibular stability six months following surgery. No statistically significant differences were observed in the postoperative skeletal and dental changes between the two techniques.Conclusion:Fixation of the mandible following the setback surgery by the BSSO technique with the one-screw fixation method may be accomplished effectively, and the therapeutic outcomes are comparable to those obtained with the traditional 3-screw fixation approach.

Changes in the pharyngeal airway after different orthognathic procedures for correction of class III dysplasia

ObjectiveThis study was conducted to compare changes in pharyngeal airway after different orthognathic procedures in subjects with class III deformity.MethodsThe study included CBCT scans of 48 skeletal class III patients (29 females and 19 males, mean age 23.50 years) who underwent orthognathic surgery in conjunction with orthodontic treatment. The participants were divided into three groups of 16, as follows: Group 1, mandibular setback surgery; group 2, combined mandibular setback and maxillary advancement surgery; and group 3, maxillary advancement surgery. CBCT images were taken 1 day before surgery (T0), 1 day (T1), and 6 months (T2) later. The dimensions of the velopharynx, oropharynx, and hypopharynx were measured in CBCT images.ResultsIn all groups, there was a significant decrease in airway variables immediately after surgery, with a significant reversal 6 months later (P < 0.05). In subjects who underwent maxillary advancement, the airway dimensions were significantly greater at T2 than the T0 time point (P < 0.05), whereas in the mandibular setback and bimaxillary surgery groups, the T2 values were lower than the baseline examination (P < 0.05). The alterations in airway variables were significantly different between the study groups (P < 0.05).ConclusionsThe mandibular setback procedure caused the greatest reduction in the pharyngeal airway, followed by the bimaxillary surgery and maxillary advancement groups, with the latter exhibiting an actual increase in the pharyngeal airway dimensions. It is recommended to prefer a two-jaw operation instead of a mandibular setback alone for correction of the prognathic mandible in subjects with predisposing factors to the development of sleep-disordered breathing.

Computer Guided Generated Dual-Purpose Splint for Bilateral Sagittal Split Osteotomy.

to evaluate the efficacy of dual-purpose computer-generated splint in guiding the proximal and the distal segment in bilateral sagittal split osteotomy. It was a prospective case series study directed on 8 class III patients indicating the need of maxillary advancement and mandibular set back by bilateral sagittal split osteotomy. A CAD/CAM splint is generated to guide the distal segment to the stable maxilla and at the same time a grooved extension to engage the proximal segment ensuring the condyle in its planned position during fixation. The primary outcome was measured by calculating the difference between the pre- and post-operative condylar segment position. The present study included five female patient and three male patient with mean age of 28.4 ± 5.1years. The accuracy of the splint in positioning the mandibular proximal segment showed promising results ranging from 2.59 to 0.49. The dual-purpose splint introduced in this study showed satisfied results in maintaining the pre-operative condylar position while securing the distal segment in the desired plan.

Volumetric Change in the Masseter and Lateral Pterygoid after Mandibular Setback.

In this study, we evaluated changes in the masseter and lateral pterygoid muscles in the prognathic mandible group after a mandibular setback by comparing the volume-to-length ratios. Preoperative and postoperative 1-year computed tomography was used to calculate the volume-to-length ratio of the lateral pterygoid and masseter muscle in 60 Korean individuals. Three-dimensional images were reconstructed, the results of which showed no significant differences in the volume-to-length ratios of the masseter and lateral pterygoid muscles after a mandibular setback (p > 0.05). This result was found for both vertical ramus osteotomy and sagittal split ramus osteotomy, and for both males and females. No significant differences in the volume-to-length ratio of the masseter and lateral pterygoid muscles were found up to 1 year after a mandibular setback. Therefore, this study can contribute to the prediction of soft-tissue profiles after mandibular setback.

LeFort III/I for Beckwith-Wiedemann Syndrome: A Case Report.

This case presents a facially mature patient with Beckwith-Wiedemann Syndrome (BWS) who presented with severe class III malocclusion. Computed tomography imaging revealed an anterior crossbite of 19 mm and a narrow pharyngeal airway at the level of the tongue base precluding mandibular setback surgery. The patient was indicated for a LeFort III combined with a LeFort I advancement, each of 10 mm, for a 20 mm combined advancement. Stable, functional occlusion was achieved without airway compromise. This novel use of the combined LeFort III/I can restore stable class I occlusion in patients with BWS at risk for tongue base airway compromise.