Setback Surgery Research Articles

Comparative study of stability between two different fixation systems after orthognathic surgery in mandibular prognathism skeleton

ObjectiveThis study is intended to compare the skeleton stability of bioabsorbable and titanium systems after orthognathic surgery in mandibular prognathism patients. Study designA Retrospective study of 28 mandibular prognathism patients who underwent BSSRO setback surgery at Chulalongkorn University. Both titanium and the bioabsorbable group would take lateral cephalometrics immediately postoperative in 1-week(T0), 3(T1), 6(T2), and 12(T3) months. These radiographs were analyzed with Dolphin imaging programTM. The vertical, horizontal, and angular indices were measured. To compare immediately postoperative and follow-up periods within the group, the Friedman difference was used, and the Man-Whitney U test was used between the two groups. ResultThe measurements within the group presented no statistically significant differences. But this study showed that at T0-T1, there was a statistically significant difference between the two groups in the mean of Me in horizontal linear measurement. T0-T2 found differences between Me in both horizontal and vertical linear measurements, and the difference between ANB. The differences between B-point, Pog, and Me in vertical linear measurements at T0-T3 were also reported. ConclusionThe significant difference values were within the normal range which indicated that using the bioabsorbable system could be well maintained as well as the titanium system. Statement of clinical relevanceThe second operation for removing titanium plate and screw after conventional orthognathic surgery may leads patient discomforts. While a resorbable system might be the role change if the stability is place on the same level.

Three Different Fixation Modalities following Mandibular Setback Surgery with Sagittal Split Ramus Osteotomy: A Comparative Study using Three-dimensional Finite Elements Analysis.

The provision of sufficient stability after maxillofacial surgery is essential for the reduction of complications and disease recurrence. The stabilization of osteotomized pieces results in rapid restoration of normal masticatory function, reduction of skeletal relapse, and uneventful healing at the osteotomy site. We aimed to compare qualitatively stress distribution patterns over a virtual mandible model after bilateral sagittal split osteotomy (BSSO) bridged with three different intraoral fixation techniques. This study was conducted in the Oral and Maxillofacial Surgery Department of Mashhad School of Dentistry, Mashhad, Iran, from March 2021-March 2022. The mandible computed tomography scan of a healthy adult was used to generate a 3D model; thereafter, BSSO with a 3mm setback was simulated. The three following fixation techniques were applied to the model: 1) two bicortical screws, 2) three bicortical screws, and 3) a miniplate. The bilateral second premolars and first molars were placed under mechanical loads of 75, 135, and 600N in order to simulate symmetric occlusal forces. Finite element analysis (FEA) was carried out in Ansys software, and the mechanical strain, stress, and displacement calculations were recorded. The FEA contours revealed that stress was mainly concentrated in the fixation units. Although bicortical screws presented better rigidity than miniplates, they were associated with higher stress and displacement readings. Miniplate fixation demonstrated the most favorable biomechanical performance, followed by fixation with two and three bicortical screws, respectively. Intraoral fixation with miniplates in combination with monocortical screws can serve as an appropriate fixation arrangement and treatment option for skeletal stabilization after BSSO setback surgery.

The Efficacy of the Partial Glossectomy for Prevention of Airway Volume Reduction in Orthognathic Surgery of Class III Patients

The aim of this study was to evaluate the effects of a partial glossectomy on volumetric changes of pharyngeal airway space (PAS) in patients with mandibular setback surgery. Overall, 25 patients showing clinical features related to macroglossia treated with mandibular setback surgery were included in this retrospective study. Subjects were divided into two groups: the control group (G1, n = 13, with BSSRO) and the study group (G2, n = 12, with both BSSRO and partial glossectomy). The PAS volume of both groups was measured by the OnDemand 3D program on CBCT taken shortly before operation (T0), 3 months post-operative (T1), and 6 months post-operative (T2). A paired t-test and repeated analysis of variance (ANOVA) were used for statistical correlation. Total PAS and hypopharyngeal airway space were increased after operation in Group 2 compared to Group 1 (p < 0.05), while oropharyngeal airway space showed no significant statistical difference with the tendency of increasing. The combination of partial glossectomy and BSSRO surgical techniques had a significant effect on increasing the hypopharyngeal and total airway space in class III malocclusion patients (p < 0.05).

Association between Bilateral Sagittal Split Osteotomy Setback and Autorotation of the Mandible

Introduction: The study aimed to evaluate the autorotation for Class III malocclusions after the bilateral sagittal split osteotomy (BSSO) setback procedure . Methodology: This retrospective study includes lateral cephalograms of eight males and three females total of 11 patients who had undergone BSSO, without any other additional surgeries. The Frankfurt-Horizontal (F-H) plane was used as a reference and manual superimposition was done. Considering stable mandibular landmarks, reference line perpendicular (RLp) and reference line (RL) were drawn as x and y coordinates, respectively. Pre- and postsurgical statistics were used to compare using paired t-test where P &lt; 0.05 was set for statistical significance. Results: Superimposed tracings showed no significant difference in pre- and postsurgical treatments. There was no statistically significant amount of autorotation after the BSSO setback procedure (P = 0.714). Conclusion: Hence, BSSO setback surgery will not cause any significant amount of autorotation of the mandible. If autorotation is required it must be incorporated into treatment planning.

Changes in Pharyngeal Airway Space and Oxygen Saturation Following Mandibular Setback Surgery: A Narrative Review.

Orthognathic surgery can alter the dental, skeletal, soft tissue, and dimensional changes in the oropharyngeal region. Studies have shown a posterior positioning of the hyoid bone and tongue position after mandibular setback surgery, this in turn can have a negative influence on the upper airway space that could lead to breathing problems such as obstructive sleep apnea. Mandibular setback surgery is commonly used for functional and aesthetic correction in mandibular prognathism patients. There are still some controversial opinions regarding the effect of mandibular setback surgery on the pharyngeal airway space and oxygen saturation. This study aims to review and illustrate the changes in pharyngeal airway space and oxygen saturation following mandibular setback surgery.

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.

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.

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.

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.

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.

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.

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.

Evaluation of mandibular positional changes after orthognathic surgery in skeletal class II and class III surgery-first approach patients

PurposeThe aim of this study was to predict and compare postoperative changes of mandibular position between mandibular setback and advancement surgery in a surgery-first approach (SFA). Materials and methodsThe study population included patients who underwent mandibular setback or advancement surgery using bilateral sagittal split ramus osteotomy, those were divided into two groups: mandibular setback and advancement surgery. Surgical and postoperative mandibular positional changes were evaluated by lateral cephalograms and CTs taken within 2 months before surgery (T0), 1 week after surgery (T1), and after the debonding procedure (T2). The postoperative mandibular positional changes were predicted from the increase in vertical dimension (VD) in surgical occlusion and the counterclockwise rotation to the preoperative VD on the lateral cephalograms and CT at T1. Furthermore, resultant measurement on postoperative mandibular positional changes was performed. Finally, we compared the prediction with actual positional changes of the mandible after the debonding procedure. ResultsNine SFA patients with mandibular setback surgery and six with advancement surgery were evaluated and significant mandibular changes from T0 to T1 and from T1 to T2 were observed. Negative correlation between horizontal surgical changes and postoperative horizontal changes was present in both groups. The difference between the predicted and actual amount of postoperative mandibular movement was significant in the mandibular advancement surgery group. ConclusionPostoperative mandibular relapse appeared much larger in the mandibular advancement surgery group than in the setback group. Therefore, it is more important to consider the postoperative mandibular position change in mandibular advancement surgery in SFA.

Bimaxillary Orthognathic Surgery Does Not Induce Obstructive Sleep Apnea in Skeletal Class III Patients

Since the relationship between mandibular setback surgery and obstructive sleep apnea (OSA) occurrence still remains controversial, the aim of this study was to assess the impact of bimaxillary orthognathic surgery on the probability of OSA development, using a home sleep test (HST) device. The authors implemented a double-blinded prospective cohort study. All healthy patients with skeletal class III deformity were included in this study. Subjects were candidates for bimaxillary orthognathic surgery. OSA monitoring was performed by the pulmonologist, week 1 preoperatively (T0), 1 and 6months postoperatively (T1, T2), with a specific brand of a HST device. The predictor variables were the amount of mandibular setback and maxillary advancement, separately. Changes in apnea-hypopnea index (AHI) and SpO2 1 and 6months after surgery relative to T0 were the outcome variables. OSA severity was measured using AHI, and classified as mild (5<AHI<15), moderate (15<AHI<30), and severe (AHI>30). Age, sex, and body mass index were the study covariates. The outcome assessor (pulmonologist), and the data analyzer were blind in this study. The significance level was set at 0.05, using the SPSS19. The sample was composed of 30 patients, (15 females, 15 males) with an average age of 25.73±5.26years and a mean body mass index of 19.90±3.6kg/m2. The mean amount of mandibular setback was 4.5±1.1 (ranged from 2-7mm), while the average maxillary advancement was 2.9±1.2mm (ranged 1-5mm). Mean AHI at T0, T1, and T2 was 1.8±1.0, 3.4±1.5, and 1.9±0.9 events per hour events, respectively. The AHI scores increased from T0 to T1 but again decreased until T2, which were statistically significant (P<.001). The mean amount of SpO2 at T0, T1, and T2 was 96.7±0.9, 94.0±1.3, 96.7±0.7%, respectively. Postoperative AHI in T1 and T2 had direct statistical significant relationships with the amount of mandibular setback (Rsp=.404, .574, respectively and P<.05). Postoperative AHI scores were lower in patients with <5mm mandibular setback in comparison to subjects who underwent ≥5mm setback (P<.05). Bimaxillary orthognathic surgery (concomitant maxillary advancement and mandibular setback) did not increase the incidence of OSA in young healthy non-obese class III patients, in the case of mandibular setback up to 7mm.

Lateral cephalometric changes and stability of BSSO versus IVRO for mandibular setback surgery: A systematic review and meta-analysis.

The aim of this review is to examine the lateral cephalometric hard tissue changes and the stability of the end result of bilateral sagittal split osteotomy (BSSO) and the intraoral vertical ramus osteotomy (IVRO) techniques for mandibular setback surgery. A systematic review of MEDLINE (via PubMed), Scopus, and Cochrane Library databases (last search date: August 22nd, 2021) was performed according to the PRISMA guidelines. Only studies that directly compare BSSO and IVRO were included. Random-effects model meta-analyses were performed. Ten studies, comprising a total of 331 patients, 169 patients undergoing BSSO and 162 patients undergoing IVRO were identified. No statistically significant differences were observed regarding the angular measurements: Sella/Nasion/B point (SNB) angle post-operatively (standardized mean difference [SMD]= 0.39, 95% Confidence Interval [CI]: [-0.15] – [0.94], p=0.16, I2=57.09%) and 1 year after surgery (SMD= 0.72, 95% CI: [-0.08] – [1.53], p=0.08, I2=80.83%), gonial angle post-operatively (SMD=0.45, 95% CI: [-0,26] – [1.15], p=0.21, I2=72.54) and 1 year after surgery (SMD= 0.15, 95% CI: [-0.79] – [1.08], p=0.75, I2=91.56%), and MP angle 1 year after surgery (SMD=-0.46, 95% CI: [-1.64] – [0.72], p=0.45, I2=90.81%). In addition, no statistically significant differences were observed regarding the linear measurements, the relapse of the mandible as measured by the relapse of B point 1 year after surgery in the horizontal axis (SMD= 0.73, 95% CI: [-0.25] – [1.72], p=0.15, I2=86.43%) and vertically (SMD= -0.76, 95% CI: [-1.97] – [0.45], p=0.22, I2=90.09%). BSSO and IVRO have similar results in terms of SNB and gonial angle relapse post-operatively and 1 year after surgery, MP angle 1 year after surgery and horizontal and vertical relapse, measured in reference to B point 1 year after surgery.

Computational Fluid Dynamic Study of the Pharyngeal Airway Characteristics Before and After Mandibular Setback Surgery in Patients with Mandibular Prognathism

Mandibular prognathism had been one of the most inconvenienced deformities developed in humans. This type of deformity possesses a protruded mandible jaw, and it can cause inconvenience in talking chewing and affect the aesthetic of the person diagnosed with this problem. However, this problem can be solved through mandibular setback surgery. This surgery will reposition the mandible jaw backward. The main concern of this surgery is, by repositioning the mandible jaw backward, the cross-sectional area of the airway will also be reduced. This condition might induce the iatrogenic of Obstructive Sleep Apnea (OSA). Thus, this study analyzed the characteristic of the pharyngeal airway in pre-treatment and post-virtual-operative conditions. This analysis simulates the pharyngeal airway with the Computational Fluid Dynamic (CFD) method. The respondent's data was obtained from computed tomography (CT) scan and was modeled into a 3-dimensional (3D) model. The simulation process takes place using the 3D model, mesh generation, and boundary conditions set-up. The flow pattern, pressure drop, airway wall shear stress, and turbulent kinetic energy were compared between both simulations. The simulations result present that, after the surgery, the pharyngeal airway decreases significantly. The pressure drop, flow pattern, airway wall shear stress (WSS), and turbulent kinetic energy (TKE) seem more significant around the critical plane in the post-treatment condition. However, these factors did not contribute to the OSA as it is not large enough to become the cause of OSA.