下颌升支垂直截骨在髁状突手术中的应用

目的：观察下颌升支垂直截骨间接治疗髁状突疾患的疗效。方法：采用下颌升支垂直截骨方式间接治疗髁状突疾患19例，其中髁状突良性肥大2例，髁状突骨瘤4例，颞下颌关节骨性强直3例，髁状突骨折10例。结果：所有患者张口度均接近或达到正常，无关节疼痛及弹响症状，随访期内无1例复发。结论：下颌升支垂直截骨间接髁状突整复是治疗髁状突疾患的一种可选择的、有效的方法。     

Three-dimensional condylar displacement and remodelling in patients with asymmetrical mandibular prognathism following bilateral sagittal split osteotomy

This study aims to assess the postoperative condylar displacement and the long-term condylar remodelling in patients with mandibular prognathism with transverse asymmetry after bilateral sagittal split ramus osteotomy (BSSRO). Forty-one consecutive patients (82 condyles) with a transverse mandibular asymmetry of more than 4 mm without occlusal canting treated by BSSRO were included. The preoperative (T1), immediate postoperative (T2) and long-term follow-up of an average of 16.2 months (T3) spiral computed tomography scans were gathered and processed to measure the condylar displacement and remodelling based on cranial base voxel-based and rigid regional registrations. The statistical analysis revealed that the majority of condyles (T1–T2) were transitionally displaced forwards, downwards and laterally, and were not fully returned to the preoperative position at T3. Condylar lateral displacement was significantly higher on the deviated side (DS) (P = 0.035). Non-deviated side (NDS) condyles were mainly subjected to upward pitch, medial yaw and medial roll compared with downward pitch, lateral yaw and lateral roll on DS. Condylar remodelling at T3 was observed, with the superior and posterior surfaces commonly subjected to bone resorption, whereas the anterior and medial surfaces were commonly subjected to bone apposition. Condylar volumetric changes were relatively comparable on NDS (3 ± 85.2 mm³) and DS (8.3 ± 111.7 mm³) condyles. Age, amount of preoperative asymmetry and follow-up period were not correlated with the condylar remodelling. Transitional and rotational displacements were to some extent significantly correlated with the condylar remodelling on both sides. Consequently, passive condylar seating without torque might prevent the long-term unfavourable condylar remodelling.     

A study of unfavorable splits in the sagittal ramus osteotomy with a short lingual cut

In the bilateral sagittal split osteotomy, a short lingual cut is made on the medial side of the ramus; however, in some cases, a true fracture occurs on the buccal side of the ramus. The purpose of this study was to evaluate the relationship between the splitting pattern of the mandible and the form of the mandible, the surgical technique used, and the postoperative occurrence of relapse after ‘unfavorable’ splits. The investigation examined 143 patients in whom a short lingual cut was attempted. The rate of unfavorable split was 14.7% (42/286). A strong correlation was observed between the reach of the lateral bone cut to the inferior border of the mandible and an unfavorable split. According to multivariate regression, the factors leading to an insufficient lateral bone cut were the degree of inward curvature of the ramus (P = 0.001) and the position of the lateral bone cut (P = 0.002). There was no significant difference in relapse between cases of unfavorable and normal splits. An unfavorable split does not affect the prognosis of the occlusion, but it is important to confirm the inward curvature of the ramus and set the position of the lateral bone cut adequately to avoid unfavorable splits.     

Surgical morbidities of sagittal split ramus osteotomy versus intraoral vertical ramus osteotomy for the correction of mandibular prognathism: a randomized clinical trial

The sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) are two common orthognathic procedures for the treatment of mandibular prognathism. This randomized clinical trial compared the surgical morbidities between SSRO and IVRO for patients with mandibular prognathism over the first 2 years postoperative. Ninety-eight patients (40 male, 58 female) with a mean age of 24.4 ± 3.5 years underwent bilateral SSRO (98 sides) or IVRO (98 sides) as part or all of their orthognathic surgery. IVRO presented less short-term and long-term surgical morbidity in general. The SSRO group had a greater incidence of inferior alveolar nerve deficit at all follow-up time points (P <  0.01). There was more TMJ pain at 6 weeks (P =  0.047) and 3 months (P =  0.001) postoperative in the SSRO group. The SSRO group also presented more minor complications, which were related to titanium plate exposure and infection. There were no major complications for either technique in this study. Despite the need for intermaxillary fixation, IVRO appears to be associated with less surgical morbidity than SSRO when performed as a mandibular setback procedure to treat mandibular prognathism.     

Position of the mandibular canal before and after bilateral sagittal split ramus osteotomy: a cone beam computed tomographic study

The aim of this study was to evaluate the position of the mandibular canal (MC) before and after bilateral sagittal split ramus osteotomy (BSSRO) using cone-beam computed tomography (CT), and to compare the position of the MC in Class II and Class III patients in the preoperative period. Patients were divided into two groups: Class II (n = 38) and Class III (n = 41). Measurements of the superior, inferior, buccal, and lingual distances of the MC in relation to the cortical bone were taken at three levels in the proximal segment of the mandible. Results were analysed using the Kruskal–Wallis test (p < 0.05). In the Class II group the superior distance of the MC at levels 2 and 3, and the inferior distance at level 3 significantly decreased after BSSRO. In the Class III group, no significant differences were found at any level, and the inferior distances at all levels were smaller preoperatively than those in the Class II group. In the Class II group the position of the MC altered in relation to superior and inferior cortical bone after BSSRO. However, the position of the MC remained stable in the Class III group. Our results also suggest a deeper cut in inferior cortical bone in Class III patients.     

骨性下颌前突正畸—正颌联合治疗前后髁突位置变化的研究

目的:研究骨性下颌前突正畸-正颌联合治疗前后髁突位置的变化,探讨下颌双侧升支矢状劈开后退术对于治疗骨性下颌前突的可靠性和安全性。方法:15例骨性下颌前突的安氏Ⅲ类错牙合畸形病人,行下颌双侧升支矢状劈开后退术(bilateral sagittal split ramus osteotomy,BSSRO)与正畸矫治联合治疗,分别在术前两周和术后半年拍摄许勒式X线片,测量BSSRO术前、术后双侧髁突在关节窝内前、后、上间隙的距离,进行统计学分析比较术前术后髁突位置的变化情况。结果:15例病例经BSSRO配合正畸治疗后均达到正常的咬合关系,恢复了口腔功能,改善了面部容貌;正颌术前:左侧关节前、后、上间隙均数为1.91、2.30、2.51 mm;右侧前、后、上间隙均数为2.14、2.65、2.98 mm;正颌术后:左侧关节前、后、上间隙均数为1.99、2.38、2.62 mm;右侧前、后、上间隙均数为2.14、2.66、2.60 mm。术后半年双侧髁突在关节窝内的上、前、后间隙与术前两周相比,差异均无统计学意义。结论:下颌双侧升支矢状劈开后退术(BSSRO)配合正畸治疗,能够安全有效的矫治骨性下颌前突,并且未使其出现新的关节症状。     

The relationship between fixation method and early central condylar sagging after bilateral sagittal split ramus osteotomy in orthognathic surgery

PurposeThere is no consensus about the ideal fixation methods and their effects on the condyle after the sagittal split ramus osteotomy (SSRO) procedure. The aim of this study was to compare the incidence, clinical presentation, and treatment of condylar sagging between different fixation methods following SSRO.MethodsPatients who underwent double jaw surgery between 2007 and 2017 were evaluated retrospectively. Mandibular fixation was maintained using one of three different options: a miniplate and a single bicortical screw, three bicortical screws, or a single bicortical screw. Some patients had malocclusion relapse in the early postoperative period due to condylar sagging, and needed reoperation. The reoperated condylar sagging patients were analysed statistically with respect to their fixation methods.Results233 patients (134 females, 99 males) with a mean age of 23.3 years were enrolled in the study. The patients fixated with a single bicortical screw had lower revision surgery rates than those with three bicortical screws or with miniplate with a single bicortical screw (p = 0.034 and p = 0.032, respectively). These differences in central condylar sagging with a need for revision were statistically significant.ConclusionAlthough a miniplate and a single bicortical screw and three bicortical screws are widely used after SSRO, if the priority is to avoid sagging then it seems that a single screw should be preferred for osteosynthesis.     

Extraoral vertical ramus osteotomy combined with internal fixation for the treatment of mandibular deformities

Extraoral vertical ramus osteotomy (EVRO) is used in orthognathic surgery for the treatment of mandibular deformities. Originally, EVRO required postoperative intermaxillary fixation (IMF). EVRO has been developed using rigid fixation, omitting postoperative IMF. We examined retrospectively the long-term stability and postoperative complications for patients with mandibular deformities who underwent EVRO with internal rigid fixation. Patients who were treated with EVRO for a mandibular deformity in the period 2008–2017 at the Clinic of Oral and Maxillofacial Surgery, Mölndal, Sweden were included (N = 26). Overjet and overbite were calculated digitally and cephalometric analyses were performed preoperatively, and at three days, six months, and 18 months postoperatively. There was a general setback of the mandible, decreased gonial angle and reduced degree of skeletal opening. Excellent dental and vertical skeletal stabilities were seen up to 18 months postoperatively, although relapse was seen sagitally up to six months postoperatively. Since the overjet did not show any significant change over time, the sagittal skeletal changes have been attributed to dental compensation. There was no permanent damage to the facial nerve and 5.8% neurosensory damage to the inferior alveolar nerve was observed.     

Comparison of postoperative stability of three rigid internal fixation techniques after sagittal split ramus osteotomy for mandibular advancement

IntroductionThe aim of this investigation was to compare the skeletal stability of three different rigid fixation methods after mandibular advancement.Material and methodsFifty-five class II malocclusion patients treated with the use of bilateral sagittal split ramus osteotomy and mandibular advancement were selected for this retrospective study. Group 1 (n = 17) had miniplates with monocortical screws, Group 2 (n = 16) had bicortical screws and Group 3 (n = 22) had the osteotomy fixed by means of the hybrid technique. Cephalograms were taken preoperatively, 1 week within the postoperative care period, and 6 months after the orthognathic surgery. Linear and angular changes of the cephalometric landmarks of the chin region were measured at each period, and the changes at each cephalometric landmark were determined for the time gaps. Postoperative changes in the mandibular shape were analyzed to determine the stability of fixation methods.ResultsThere was minimum difference in the relapse of the mandibular advancement among the three groups. Statistical analysis showed no significant difference in postoperative stability. However, a positive correlation between the amount of advancement and the amount of postoperative relapse was demonstrated by the linear multiple regression test (p < 0.05).ConclusionIt can be concluded that all techniques can be used to obtain stable postoperative results in mandibular advancement after 6 months.     

The stability of bilateral sagittal ramus osteotomy and vertical ramus osteotomy after bimaxillary correction of class III malocclusion

Introduction

The purpose of this retrospective cephalometric study was to compare the stability of bilateral sagittal split osteotomy (BSSO) with extra-oral vertical ramus osteotomy (VRO) after correction of class III malocclusion by means of bimaxillary orthognathic surgery.

Methods

The sample comprised 51 consecutively treated patients, 38 females and 13 males, with a mean age of 19.1 years. All had a one-piece Le Fort I osteotomy with maxillary advancement and mandibular setback. VRO was performed in 30 cases, and BSSO was performed in 21 cases. Lateral cephalograms were obtained before surgery, within 1 week of surgery and 1 year after surgery.

Results

The mean forward movement of the maxilla was 5.6 mm in both groups (p < 0.001). The mean horizontal surgical change in the VRO group was 4.4 mm (p < 0.001), and in the BSSO group it was 5.4 mm (p < 0.001). In the VRO group, the horizontal relapse was 1.2 mm (p < 0.001), and in the BSSO group, it was 1.4 mm (p < 0.001).

Conclusion

There was no difference in the stability between the BSSO and VRO groups. The average relapse in the whole sample was 26% of the surgical movement.     

Penetration of inferior alveolar nerve canal increased by bicortical fixation after bilateral sagittal split osteotomy in mandibular prognathism

The purpose of this three-dimensional cone beam computed tomography (CBCT) study was to identify the difference between monocortical fixation (MCF) and bicortical fixation (BCF) in mandibular canal penetration after bilateral sagittal split osteotomy (BSSO) to correct mandibular prognathism, where interosseous fixation was done by BCF or MCF. CBCT was performed 1 week postoperatively and Dolphin 3D software was used to assess direct penetration of the mandibular canal by either type of screw. The primary outcome variable was the presence or absence of mandibular canal penetration and was categorized as a binary coded variable. The BCF and MCF groups were compared by χ² test, and the odds ratio for canal penetration was estimated. Multiple logistic regression was performed to identify factors related to canal penetration. A total of 118 patients were included. The MCF group had only 6% canal penetrations (3/50 patients) and the BCF group had 58.8% canal penetrations (40/68 patients). The regression model showed that BCF was the only factor causing mandibular canal penetration, with an adjusted odds ratio of 52.5. Awareness of the increased risk of canal penetration with BCF and potential nerve injury might influence case selection.     

下颌骨双侧升支矢状劈开双皮质螺钉内固定的生物力学分析

目的:对下颌骨升支矢状劈开不同方式双皮质固位螺钉内固定进行三维有限元分析,为临床提供理论指导。方法:建立下颌骨升支矢状劈开6种双皮质螺钉固定方式的三维有限元模型;计算不同固定方法在3种咬合情况下颌骨的应力、内固定系统的应力以及骨劈开处的位移,对比这些固定方式的固定效果以及不同咬合情况对固定稳定性的影响。结果:在相同咬合情况下,颌骨的应力、内固定系统的应力以及劈开处的位移的大小情况如下:单纯上缘固定大于倒"L"型固定;直径2.0mm大于直径2.7mm螺钉固定;倒"L"型60°大于倒"L"型90°和120°固定;间距2.0cm大于间距3.0cm固定。相同固定方式情况下,颌骨的应力、内固定系统的应力以及劈开处的位移从大到小排列顺序为:前牙咬合、前磨牙咬合、磨牙咬合。结论:双皮质固位螺钉内固定的排列方式,如:间距、角度、位置和内固定系统的规格均对固定稳定性有不同程度的影响;前牙咬合对固定的不良影响最大,应尽量避免。     

下颌支矢状骨劈开术并发症防治的专家共识

下颌支矢状骨劈开术（SSRO）是正颌外科中最为常用的一类矫治下颌骨畸形的手术。由于局部解剖和操作步骤的复杂性,SSRO出现各类并发症的可能性较大,甚至可能造成严重的不良后果。诊疗策略的选择及转归与并发症的类型及其临床表现密切相关。为此,国内相关专家编写本共识,对SSRO各类常见并发症的原因、预防、处置措施进行阐述,以期提高广大同行对SSRO并发症的认识,确保手术安全进行并获得良好效果。     

The use of xenografts to prevent inferior border defects following bilateral sagittal split osteotomies: three-dimensional skeletal analysis using cone beam computed tomography

The aim of this retrospective study was to investigate grafting in the osteotomy gap during bilateral sagittal split osteotomy (BSSO), using a xenograft and fibrin glue. Hard tissue defects in the inferior mandibular border were assessed using cone beam computed tomography scans taken 1 week and 1 year postoperatively. The study group of 20 patients underwent bone grafting during BSSO (mean age 26.1 years; mean horizontal displacement 8.5 mm) and the control group of 20 patients did not (mean age 30.2 years; mean horizontal displacement 7.6 mm). The mean height of the mandibular defects was significantly lower in the study group, but there was no significant difference in volume measurements between the groups. Grafting had a negligible effect on large displacements (9.0–15.0 mm), which might have been due to an inadequate amount and/or positioning of the graft, or to poor dimensional stability. This may be resolved by improved graft positioning or by using a different kind of (xeno)graft.     

Independent risk factors for long-term skeletal relapse after mandibular advancement with bilateral sagittal split osteotomy

The purpose of this retrospective cohort study was to identify the independent risk factors for long-term skeletal relapse following mandibular advancement with bilateral sagittal split osteotomy. Univariate and multivariate linear regression analyses were performed including nine common risk factors for relapse as independent variables and horizontal/vertical long-term (≥2 years) skeletal relapse as dependent variables. Ninety-six patients were analyzed; 66 were female (68.8%) and the average age of the patients was 29.7 ± 10.5 years. Over an average follow-up of 3.8 ± 1.8 years after an initial mandibular advancement of 8.8 ± 2.4 mm, long-term skeletal relapse of 1.6 ± 1.0 mm horizontal and 0.9 ± 0.7 mm vertical was found. Multivariate analysis identified age, preoperative mandibular plane angle (MPA), bimaxillary surgery, counterclockwise mandibular rotation, and the magnitude of mandibular advancement to be significantly associated with horizontal long-term skeletal relapse. Preoperative MPA, counterclockwise mandibular rotation, and the magnitude of mandibular advancement were significantly associated with vertical long-term skeletal relapse. Thus preoperative MPA, the magnitude of mandibular advancement, and counterclockwise mandibular rotation of the mandible were found to be independent risk factors for both horizontal and vertical long-term skeletal relapse. Although long-term skeletal relapse cannot be avoided entirely, understanding the independent risk factors and their contributions will optimize treatment planning and long-term stability.     

The influence of bilateral sagittal split ramus osteotomy on submental‐cervical aesthetics

The effect of orthodontic‐surgical treatment on submental‐cervical region was evaluated in a very limited number of studies. The aim of this study was to evaluate submental‐cervical soft tissue contour changes following mandibular advancement and set‐back procedures via bilateral sagittal split ramus osteotomy. Sixty‐seven patients were included in this study. Group 1 consisted of 27 skeletal Class II patients who underwent mandibular advancement surgery, whereas Group 2 consisted of 40 skeletal Class III patients who underwent mandibular set‐back surgery. Various linear and angular measurements were performed on pre‐operative and sixth month post‐operative cephalometric radiographs. A new method was used to evaluate the amount of sagging at submental region. The submental length did not change in Group 1; however, it decreased significantly in Group 2 (P < 0·05). The angle between submental plane and facial plane decreased to 95·9° from 98·8° in Group 1(P < 0·05), whereas it increased to 93·1° from 88·2° in Group2 (P < 0·05). The change of submental soft tissue sag was almost stable in Group 1, while 0·34 mm increase of sag was observed in Group 2. This increase was not statistically significant (P > 0·05). Mandibular set‐back and advancement procedures do not remarkably change the submental sag following approximately 6 mm jaw movement. Although mandibular advancement did not significantly effect submental length, soft tissue followed mandibular set‐back with a ratio of 1:1 at C‐point to projection of soft tissue pogonion and 1:0·7 at C‐point to soft tissue menton distances.     

Antibiotic prophylaxis for sagittal split ramus osteotomy using resorbable plate and screw fixation: a randomised trial to compare extended dual-agent and inpatient single-agent regimens

Resorbable materials are used to fix bony fragments after sagittal split ramus osteotomy (SSRO), but to our knowledge, there is no clear regimen for antibiotic prophylaxis when such materials are used. The purpose of this study therefore was to compare inpatient single-agent and extended dual-agent antibiotic prophylaxis for the prevention of surgical site infections (SSI) in patients after SSRO. This prospective study included 100 patients who underwent SSRO for deformities of the jaw. Cephalometric analysis was performed preoperatively, and at one month and one year postoperatively. Patients were divided into two groups of 50 each. Group A was given cefazolin sodium 1g preoperatively and every eight hours for 48 hours postoperatively. Group B was given cefazolin sodium 1g preoperatively and every eight hours for 48 hours postoperatively, after which they were provided with oral amoxicillin for three days. Both groups were assessed for SSIs for one year postoperatively using the Clavien-Dindo classification. SSIs were documented in seven patients in Group A and six in Group B, with no significant difference between the groups. The two regimens had no significant association with SSI. In conclusion, our results suggest that the inpatient, single-agent, postoperative antibiotic regimen is sufficient to prevent SSI in patients who have SSRO with resorbable plate and screw fixation.     

Ambulatory sagittal split ramus osteotomy: strategy for enhanced recovery after surgery

The sagittal split ramus osteotomy (SSRO) has been performed mainly on an inpatient basis because of the duration of anaesthesia and the potential risk of postoperative complications, such as bleeding, pain, nausea, and vomiting. However, advances in both surgical and anaesthetic management have enabled the reduction of these risks and shortened the length of hospital stay. Thus, the SSRO may be feasible even in the ambulatory setting in elective cases. The clinical records of all patients who underwent an outpatient SSRO between August 2011 and September 2020 at Lilla Craniofacial Clinic were reviewed retrospectively. Data on age, sex, duration of surgery, operative procedures, intraoperative bleeding, and admission status were investigated. In total, 143 patients underwent a bilateral SSRO. The SSRO was performed as an isolated procedure in 73 patients and concomitantly with other surgical procedures in the remaining 70 patients. Overall, 142 of the 143 patients were discharged on the day of surgery (99.3%); only one (0.7%) required an overnight stay because of a submental haemorrhage after genioplasty. No emergency hospitalizations or readmissions occurred after discharge. Multimodal perioperative management, both surgical and anaesthetic, facilitated enhanced patient recovery after surgery, and SSRO was performed successfully and safely as an ambulatory procedure.     

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.     

Study of condylar positional changes after sagittal split osteotomy for mandibular advancement: A prospective cohort study

Purpose

To analyse the possible morphologic and positional changes of the mandibular condyles after orthognathic surgery.