Skeletal stability after mandibular setback surgery: Comparison between the hybrid technique for fixation and the conventional plate fixation using an absorbable plate and screws

PurposeThe purpose of this study was to compare the temporal changes in condylar long axis and skeletal stability after sagittal split ramus osteotomy (SSRO) with the hybrid fixation technique and the conventional plate fixation.Patients and methodsOf 44 Japanese patients diagnosed with mandibular prognathism, 22 underwent SSRO with the conventional plate fixation (1 u-HA/PLLA plate and 4 monocortical screws in each side) and 22 underwent SSRO with a hybrid fixation technique (1 u-HA/PLLA plate and 4 monocortical screws and bicortical screw in each side). The temporal changes in condylar long axis and skeletal stability were assessed by axial, frontal, and lateral cephalograms. After surgery, breakage of the plate and screws was checked by 3-dimensional computed tomography (3DCT).ResultsAlthough there was a significant difference between the groups regarding Me–Ag in T1 (P = 0.0138), there were no significant differences between the groups for the other measurements in lateral, frontal and axial cephalometric analysis in each time interval. In two cases, 4 sides in the conventional plate fixation group, failure of the absorbable plate was found by 3DCT. However, there was no breakage in the hybrid fixation group.ConclusionThis study suggested that there were no significant differences in the postoperative temporal changes between the two groups in mandibular setback surgery.     

Skeletal Class III and open bite treated with bilateral sagittal split osteotomy and molar intrusion using titanium screws

Two-jaw surgery has been performed for the treatment of severe skeletal open bite cases to obtain stability of occlusion after treatment. If molar intrusion with titanium screws could be performed instead of surgical superior repositioning of the maxilla, the incidence of surgical invasion would be reduced. However, there have been few reports of such a therapy. This case report describes treatment for skeletal Class III and open bite with bilateral sagittal split osteotomy and intrusion of the molars using titanium screws. The patient had a concave profile, a long lower facial height, Class III malocclusion, and excessive anterior open bite following mandibular protrusion and a high mandibular plane angle. The mandible autorotated closed 3.5° following intrusion of the upper and lower molars using titanium screws during the presurgical orthodontic treatment phase. After the autorotation of the mandible, a mandibular setback with a bilateral sagittal split osteotomy was performed. The posttreatment records showed a good facial profile and occlusion. The mandible was stable 1 year after surgery. These results demonstrate that surgical orthodontic treatment combined with bilateral sagittal split osteotomy and intrusion of the molars using titanium screws can reduce the need for surgical invasion by avoidance of maxillary surgery and was effective for correcting the facial profile and occlusion in a skeletal Class III and open bite patient.     

Comparison of lower lip hypoesthesia between hybrid fixation and conventional fixation following sagittal split ramus osteotomy

PurposeThe purpose of this study was to compare the recovery period of lower lip hypoesthesia between hybrid fixation and conventional fixation using absorbable plates and screw systems following sagittal split ramus osteotomy (SSRO).Subjects and methodsThe subjects were 66 patients (132 sides) who underwent bilateral SSRO setback surgery. They were divided into a hybrid fixation group (66 sides, 1 u-HA/PLLA plate and 4 mono-cortical screws and a bi-cortical screw in each side) and a conventional fixation group (66 sides, 1 u-HA/PLLA plate and 4 mono-cortical screws in each side). Trigeminal nerve hypoesthesia at the region of the lower lip was assessed bilaterally by the trigeminal somatosensory-evoked potential (TSEP) method.ResultsThe mean measurable periods were 8.1 ± 10.4 weeks in the hybrid fixation group, 5.1 ± 11.5 weeks in the conventional group with no significant difference. However, the maximum in the hybrid fixation group was 27 sides at 4 weeks postoperative and in the conventional fixation group was 37 sides at 1 week postoperative, and there was significant difference in the distribution of the measurable period (P < 0.0001).ConclusionThis study suggested that additional bi-cortical screws could affect the recovery of lower lip hypoesthesia after SSRO with bent absorbable plate fixation.     

Relapse after SSRO for mandibular setback movement in relation to the amount of mandibular setback and intraoperative clockwise rotation of the proximal segment

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 11.2 mm, the mean intraoperative clockwise rotation of the proximal segment was 4.3° and the amount of postoperative relapse at point B was 2.3 mm (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.     

3D vector analysis of mandibular condyle stability in mandibular setback surgery with bicortical bioabsorbable screw fixation

IntroductionBioabsorbable screws became widely used for stable fixation in orthognathic surgery as biomechanical technology advanced. Recently, 3D image analyses begin to be used to evaluate surgical changes. The purpose of this study was to evaluate, using 3D vector analysis, the stability of bicortical bioabsorbable screw fixation in mandibular setback using a sagittal split ramus osteotomy.Spatial change of the mandibular condyle was determined by 3D coordinates containing directional information.Materials and methodsBicortical screw fixation was performed using either a bioabsorbable screw (25 patients) or a titanium screw (5 patients) in orthognathic surgery. Pre- and post-operative CT images (6 months after surgery) were superimposed digitally. A 3D coordinate (X, Y, Z) and vectors were employed to quantify spatial changes of the condyle and analysed statistically.ResultsMeasuring on 3D image showed stable error about 0.16 mm. There were no significant differences in the total spatial changes of the condyle between titanium and bioabsorbable screws with the exception of the lateral–medial direction of the condylar centre (P = 0.042). The directional vector components were stable, regardless of mandibular setback.ConclusionIn 3D vector analysis, bioabsorbable screw fixation in SSRO with distal segment osteotomy shows clinically acceptable postoperative condylar position stability.     

双颌手术升支截骨后退术后下颌稳定性及与关节关系的研究

目的　探讨升支矢状劈开截骨术(BSSRO)小钛板坚固内固定与口内入路升支垂直截骨术(BIVRO)下颌后退术后颌稳定性的不同规律,了解导致复发的有关因素特别是髁状突移位在不同手术后复发过程中的意义。方法　升支截骨手术后退下颌的患者共38例,皆为双颌手术,其中下颌BSSRO19例,BIVRO后退术19例。于手术前1周(T1),手术后1周(T2),3个月(T3)及1年(T4)分别拍摄定位头颅侧位片及定位颞下颌关节薛氏位片用于测量下颌移动幅度及关节髁状突的手术后移位。结果　双颌手术下颌升支截骨后退术后,BSSRO坚固内固定组1年时的复发率为25%,而BIVRO组大部分患者1年时下颌发生了与手术目的相同的移动,两组的不稳定主要发生在术后3个月内。结论　手术使髁状突移位术后位置的调整可导致BIVRO术后的下颌继续后移而不稳定,而髁状突近心骨段术中向后旋转术后位置的调整可导致BSSRO术后的下颌骨继续向前而不稳定     

Evaluation of overlapped cortical bone area after modified plate fixation with bent plate in sagittal split ramus osteotomy

PurposeThe purpose of this study was to evaluate bony change in an overlapped cortical bone area at the anterior site of the proximal segment after modified plate fixation with a bent plate in sagittal split ramus osteotomy (SSRO).Subjects and methodsThe subjects were 66 patients (132 sides) who underwent bilateral SSRO setback surgery. After the surgery in SSRO, an overlapped area of cortical bone at the anterior site of the proximal segment was not removed to keep the contact area between the proximal and distal segments intact, and was fixed with a bent plate and 4 screws in each side of the mandible. At the posterior site, a 3–7 mm gap was maintained between the proximal and distal segments to prevent inward-rotation of the condylar long axis. Ramus width, lateral cortex width and lateral cortex step angle were assessed in a coronal image immediately after the surgery, and 1-year postoperative by computed tomography (CT).ResultsRamus width after 1-year was significantly larger than that before surgery and smaller than that immediately after surgery in both sides (P < 0.0001). Lateral cortex width after 1-year was significantly larger than the preoperative value and smaller than that immediately after surgery in both sides (P < 0.0001). Lateral cortex angle after 1-year was significantly larger than the preoperative value in both sides (P < 0.0001).ConclusionThe above findings suggested that the overlapped cortical bone decreased thickness and the cortical bone step disappeared following favourable bone remodelling after 1-year, even though the cortical bone was not removed at the anterior site of the proximal segment.     

Stability of bioresorbable plates following reduction of mandibular body fracture: Three-dimensional analysis

PurposeThe recent development of bioresorbable bone plates and screws allows plates to be applied to the load-bearing regions of the mandible and to remain in place over time without the need for removal. We hypothesized that the stability of composite plates and screws forged from unsintered hydroxyapatite particles and poly-l-lactide (u-HA/PLLA) is comparable to that of standard titanium fixation systems for the reduction of fractures of load-bearing regions of the mandibular body.Materials and methods40 patients underwent open reduction and internal fixation of the fractured mandibular body with either a titanium or u-HA/PLLA bone plate. Cone-beam CT images were obtained immediately postoperatively and at 6-month follow-up, and were analyzed for positional changes of the affected mandible.ResultsThere were no significant differences in the postoperative positional changes of reference points between the titanium and u-HA/PLLA miniplates, except for that for the coronoid process (p-value = 0.03). Multivariate regression analysis revealed no significant differences in spatial changes between the immediate postoperative and 6-month follow-up images, after adjusting for age and sex.ConclusionThe stability of bioresorbable u-HA/PLLA miniplates and screws was comparable to that of titanium miniplates and screws immediately postoperatively and at 6-month follow-up, following surgical reduction of fractures of load-bearing regions of the mandibular body. Bioresorbable osteosynthesis can be considered a viable alternative to titanium osteosynthesis.     

双侧升支矢状劈开截骨后退下颌术后骨的稳定性的研究

目的：探讨双侧升支矢状劈开截骨术（BSSRO）后退下颌骨以钢丝结扎固定两骨段加颌间固定术后骨的稳定性，了解导致复发的有关因素。方法：双侧下颌升支矢状劈开截骨手术后退下颌的患者14例，于手术前1周，手术后1周，术后6个月分别拍摄定位头颅侧位片及许勒位X线片，用于测量下颌移动的距离及确定下颌骨髁状突的位置。结果：双侧下颌升支矢状劈开截骨后退术后，6个月的复发率为27.2%，多元逐步回归分析示下颌后退的距离与复发相关。结论：BSSRO后退下颌骨的距离越大，术后下颌骨向前移位的可能越大。     

下颌支矢状劈开术不同固定方式对下牙槽神经功能的影响

目的 研究下颌支矢状劈开术（SSRO）常用两种内固定方式对下齿槽神经（IAN）功能的影响。方法 成年恒河猴12只，均行双侧SSRO后退术。左侧行双皮质骨螺钉固定，右侧行单皮质螺钉与夹板固定。于术前、术后即刻及术后2、4、8、12周时对两侧IAN行感觉神经动作电位（SNAP）检查。结果 SSRO术后即刻SNAP检测示IAN潜伏期延长，波幅减小，较术前有显著差异（P〈0.01），但两侧之间无显著差剐。术后2周起，IAN功能逐渐恢复。至术后12周时右侧IAN的潜伏期基本恢复至术前水平，左侧IAN潜伏期较术前延长15．4％（P〈0．05）；右侧的波幅恢复也要优于左侧（P〈0．05）。结论 SSRO术中使用双皮质螺钉固定舜口单皮质螺钉夹板固定对IAN功能均有影响，但随着时间的延长，IAN功能均有恢复。单皮质骨螺钉与夹板固定相对于双皮质骨螺钉固定对1AN的功能影响要小。     

Change in condylar position in posterior bending osteotomy minimizing condylar torque in BSSRO for facial asymmetry

During the correction of an asymmetric mandible with sagittal split ramus osteotomy (SSRO), bony interference between the proximal and distal segments inevitably occurs. This results in positional change of the condyle. In order to avoid this, a posterior bending osteotomy (PBO) has been introduced. This is an additional vertical osteotomy posterior to the second molar after SSRO. To investigate the change in condylar position after SSRO with PBO, 22 patients with facial asymmetry were enrolled and divided into two groups based on the surgical method used to remove the bony interference after SSRO: PBO (n = 13) and the grinding method (n = 9). Each group was subdivided into large and small bony interference groups by estimating the volume of bony interference with simulation surgery. Condylar displacement was evaluated by three-dimensional superimposition and the amount of condylar displacement was calculated. The positional changes of the condyles were variable in each patient. When comparing patients with large bony interference in the PBO and grinding groups, the condyles were significantly inwardly rotated in the grinding group (p < 0.05). The grinding method can be used to remove small bony interferences with tolerable condylar torque. However, PBO would be beneficial in correcting large bony interferences while minimizing condylar torque.     

Skeletal stability and condylar position related to fixation method following mandibular setback with bilateral sagittal split ramus osteotomy

PurposeTo investigate postoperative intersegmental displacement and relapse following bilateral sagittal split ramus osteotomy (BSSRO) by comparing three different fixation methods: group A (sliding plate), group B (miniplate) and group C (bicortical screws).Materials and methodsThe present retrospective study included 55 patients with mandibular prognathism who were treated with BSSRO. To evaluate skeletal changes, cone-beam computed tomography was taken before surgery (T0), three days after surgery (T1), and 6 months after surgery (T2). Differences among the three groups were assessed using a one-way analysis of variance, where P < 0.05 was accepted as statistically significant.ResultsThere were no significant differences among the three groups in demographic data and the amount of mandibular setback. In skeletal changes and condylar axis changes, there were no statistically significant differences among the three groups. However, there were statistically significant postoperative skeletal changes in group C (bicortical screws) at all landmarks. The mean horizontal relapse rate was 1.9% in group A (sliding plate); 4.8% in group B (miniplate); and 15.4% in group C (bicortical screws).ConclusionThe sliding plate system has good adaptability to the proximal segment after mandibular setback with BSSRO, and behaves according to semi-rigid fixation principles.     

Anchorage value of surgical titanium screws in orthodontic tooth movement

The aim of this study was to evaluate the clinical stability and anchorage value of titanium screws in orthodontic tooth movement. Nine patients, who needed maximum anchorage for canine retraction, were selected. Records of 10 patients with similar malocclusions who had received conventional treatment were used as controls. In the maxilla and mandible 27 mini-screws, diameter 2mm and length 9 or 11 mm, were used. At the end of the first stage of orthodontic treatment the first premolar teeth were extracted after taking a lateral cephalometric radiograph. After 1 week, a retraction force of 180 g was applied to the canines. The second cephalometric X-rays were taken and evaluated after the completion of canine retraction (mean duration of 23.2 weeks). Results were analysed using Fisher Exact, Wilcoxon signed ranks and paired t-tests. Displacement of the first molars and screws before and after treatment showed no significant changes in either the vertical or horizontal plane. The first molar movements in the study and control groups were only significant in the antero-posterior plane in both maxilla and mandible. Of the 9 screws in maxilla and 18 screws in mandible, 2 and 3 screws showed clinical failure, respectively. The failed screws were replaced by other screws that withstood the applied force until the end of treatment. In conclusion, titanium screws can be used reliably as a form of anchorage.     

Stability of skeletal class III malocclusion after combined maxillary and mandibular procedures: rigid internal fixation versus wire osteosynthesis of the mandible.

PURPOSE: The aim of this study was to evaluate skeletal stability after double-jaw surgery for correction of skeletal Class III malocclusion to assess whether there were any differences between wire and rigid fixation of the mandible. PATIENTS AND METHODS: Thirty-seven Class III patients had Le Fort I osteotomy stabilized with plate and screws for maxillary advancement. Bilateral sagittal split osteotomy for mandibular setback was stabilized with wire osteosynthesis and maxillomandibular fixation for 6 weeks in 20 patients (group 1) and with rigid internal fixation in 17 patients (group 2). Lateral cephalograms were taken before surgery, immediately after surgery, 8 weeks after surgery, and 1 year after surgery. RESULTS: Before surgery, both groups were balanced with respect to linear and angular measurements of craniofacial morphology. One year after surgery, maxillary sagittal stability was excellent in both groups, and bilateral sagittal split osteotomy accounted for most of the total horizontal relapse observed. In group 1, significant correlations were found between maxillary advancement and relapse at the posterior maxilla and between mandibular setback and postoperative counterclockwise rotation of the ramus and mandibular relapse. In group 2, significant correlations were found between mandibular setback and intraoperative clockwise rotation of the ramus and between mandibular setback and postoperative counterclockwise rotation of the ramus and mandibular relapse. No significant differences in postoperative skeletal and dental stability between groups were observed except for maxillary posterior vertical position. CONCLUSIONS: Surgical correction of Class III malocclusion after combined maxillary and mandibular procedures appears to be a fairly stable procedure independent of the type of fixation used to stabilize the mandible.     

Stability of osteosynthesis with bicortical screws placed in a triangular shape in mandibular sagittal split 5 mm advancement osteotomy: Biomechanical tests

Sagittal split ramus osteotomy (SSRO) is common in orthognathic surgery, and osteosynthesis with bicortical titanium screws placed in a triangular shape is used for stabilisation. We biomechanically tested the stability of this configuration in 5 mm advancement SSRO with condylar replacement in the initial position using six fresh frozen human mandibles raised subperiosteally for surgical simulation. Osteotomy was done after marking the initial positions of the condyles and the symphysis on graph paper. The condyle was set in its initial position and the symphysis advanced exactly 5 mm; this position was maintained during osteosynthesis using 2.7 mm bicortical screws placed in a triangular shape. The mandible was then placed horizontally on the testing machine and a continuous static force was applied perpendicularly at a displacement speed of 5 mm/min. A stainless steel plate was used to transmit the forces independently of the teeth.A mean force of 129.6 Newtons (N) was applied at the elastic/plastic limit on an effort/displacement curve, which is well beyond the maximal mean (SD) chewing forces of 21 N (14) measured after bilateral sagittal split ramus osteotomy (BSSRO). A linear equation relating force to displacement was worked out from this experiment.Osteosynthesis using three bicortical screws mounted triangularly after advancement SSRO of 5 mm is experimentally stable, and our results could be used experimentally to compare two osteosyntheses using the equation.     

Evaluation of condylar resorption rates after orthognathic surgery in class II and III dentofacial deformities: A systematic review

The purpose of this study was to perform a systematic review of morphological alterations in the condyles after orthographic surgery involving a sagittal split ramus osteotomy (SSRO), with or without surgery on the maxilla. Searches were performed on three databases and registered in the PROSPERO. The selected studies fulfilled the criteria established by the following PICO model: (1) population: individuals with skeletal dentofacial deformities (class II or III facial patterns), without asymmetry; (2) intervention: orthognathic surgery for mandibular setback using an SSRO, with or without a Le Fort I osteotomy, and fixed with bicortical screws or plates and screws; (3) comparison: orthognathic surgery for mandibular advancement using an SSRO, with or without a Le Fort I osteotomy, and fixed with plates and screws or bicortical screws; and (4) outcome: condylar resorption rate and relapse. Initially, 1,371 articles were identified and 636 articles were screened after elimination of duplicates, and 6 articles were selected for qualitative analysis based on the inclusion and exclusion criteria. Five studies had data regarding the rate of condylar resorption, varying from 0.0% to 4.2%. In conclusion, condylar resorption and relapses were present in a small percentage of patients studied.     

Correlation between intraoperative proximal segment rotation and post-sagittal split ramus osteotomy relapse: a three-dimensional cone beam computed tomography study

This study evaluated the effects of proximal segment rotation and the extent of mandibular setback on post-sagittal split ramus osteotomy (SSRO) relapse using three-dimensional (3D) analysis. Thirty-one patients diagnosed with a skeletal class III malocclusion who underwent SSRO alone were enrolled in this study. The movements of the mandibular condyles were assessed using cone beam computed tomography (CBCT) and a 3D imaging program at ≤1 month before the operation (T0), 1 week after the operation (T1), and 6 months (T2) and 1 year (T3) postoperative. Yaw and roll were increased at T1 as compared to T0. However, the proximal segments reverted to their original positions between T2 and T3. There was a positive correlation between the extent of the posterior movement of the mandible and relapse at 6 months and 1 year postoperative. Although the proximal bone segments showed displacement in three dimensions at T1, they reverted to their original positions over time. In addition, although there was a positive correlation between the extent of the posterior movement of the mandible and the occurrence of post-surgical relapse at 6 months and 1 year post-surgery, the rotation of the proximal bone segment during surgery had no relationship with postoperative relapse.     

Postoperative changes in mandibular prognathism surgically treated by intraoral vertical ramus osteotomy

This study investigated short- and long-term postoperative skeletal changes following intraoral vertical ramus osteotomy (IVRO) for mandibular prognathism, as determined from lateral cephalograms. The subjects were 20 patients with mandibular prognathism who had undergone surgical orthodontic treatment combined with IVRO. Lateral cephalograms were taken at six time points: 1 month before surgery, and 1 day, 3 months, 6 months, 1 year, and approximately 2 years after surgery. Intermaxillary fixation (IMF) with four monocortical screws was maintained for 1 week in all patients. Mean posterior movement of the menton (Me) was 5.9 mm at surgery. 3 months after surgery, the FMA and FH-CorMe angles had increased 6.3 and 6.2 degrees, respectively, indicating clockwise rotation of the distal segment of the mandible. This rotation was observed in all 20 patients, suggesting that postoperative rotation of the mandible in the postoperative short term is likely to occur after IVRO and could be considered an adaptation of the mastication system newly established by surgery. In the long term after IVRO, Me had moved anteriorly by only 0.9 mm and the relapse ratio was 15.3%. These findings suggest the excellent long-term stability of surgical orthodontic treatment combined with IVRO in patients with mandibular prognathism.     

Stability of skeletal Class III malocclusion after combined maxillary and mandibular procedures: titanium versus resorbable plates and screws for maxillary fixation.

PURPOSE: The aim of this study was to evaluate skeletal stability after double jaw surgery for correction of skeletal Class III malocclusion to assess if there were any differences between resorbable plate and screws and titanium rigid fixation of the maxilla. PATIENTS AND METHODS: Twenty-two Class III patients had bilateral sagittal split osteotomy for mandibular setback stabilized with rigid internal fixation. Low level Le Fort I osteotomy for maxillary advancement was stabilized with conventional titanium plate and screws in 12 patients (group 1) and with resorbable plate and screws in 10 patients (group 2). Lateral cephalograms were taken before surgery, immediately postoperatively, 8 weeks after surgery, and 1 year postoperatively. RESULTS: Before surgery both groups were balanced with respect to linear and angular measurements of craniofacial morphology. One year after surgery, maxillary stability was excellent in both groups. In group 1 no significant correlations were found between maxillary advancement and relapse. In group 2, significant correlations were found between maxillary advancement and relapse at A point and posterior nasal spine. No significant differences in postoperative skeletal and dental stability between groups were observed. CONCLUSION: Surgical correction of Class III malocclusion after combined maxillary and mandibular procedures appears to be a fairly stable procedure for maxillary advancements up to 5 mm independently from the type of fixation used to stabilize the maxilla. Resorbable devices should be used with caution for bony movements of greater magnitude until their usefulness is evaluated in studies with large maxillary advancements.     

Effect of fixation method on intergonial width stability after mandibular setback via bilateral sagittal split osteotomy

Q4: Horizontal changes occur following bilateral sagittal split osteotomy (BSSO) in skeletal class III patients. The aim of this study was to assess the ostoperative changes in intergonial (IG) width and compare them between the positional screw and miniplate fixation methods in BSSO. This study evaluated patients who had mandibular prognathism and underwent BSSO for mandibular setback. Internal fixation was performed bilaterally, either with positional screws in the lateral ramus or with a miniplate. Postero-anterior cephalograms were obtained preoperatively (T1), at 1 month postoperative (T2), and at 6 months postoperative (T3). The IG widths and the alterations in IG width postoperative (T2 − T1, T3 − T2) were measured. No correlations were observed between the amount of setback and changes at T2  − T1 or T3 − T2. The IG width values decreased after mandibular setback and internal fixation with both methods. Statistical analyses showed a significant difference between T3 and T1 in the miniplate group (P = 0.045). No significant difference in the postoperative change in IG width (T2 − T1 and T3 − T2) was found between the two fixation groups. The magnitude of this change was smaller for positional screws when compared to miniplates for fixation. The amount of mandibular setback showed no correlation with postoperative changes in IG width..