Long-term stability of mandibular setback surgery: a follow-up of 80 bilateral sagittal split osteotomy patients

The objective of this cephalometric study was to evaluate skeletal stability and time course of postoperative changes in 80 consecutive mandibular prognathism patients operated with bilateral sagittal split osteotomy (BSSO) and rigid fixation. Lateral cephalograms were taken on 6 occasions: immediately preoperative, immediately postoperative, 2 and 6 months postoperative, and 1 and 3 years postoperative. The results indicate that BSSO with rigid fixation for mandibular setback is a fairly stable clinical procedure. Three years after surgery, mean relapse at pogonion represented 26% of the surgical setback (19% at point B). Most of the relapse (72%) took place during the first 6 months after surgery. Clockwise rotation of the ascending ramus at surgery with lengthening of the elevator muscles, though evident in this study and apparently responsible for the early horizontal postoperative changes, does not seem to be associated with marked relapse. Changes occurring in some of the younger patients between 1 and 3 years postoperatively are likely to be manifestations of late mandibular growth.     

Endoscopic-assisted repair of subcondylar fractures

OBJECTIVE: To evaluate outcomes of a series of mandibular subcondylar fractures repaired with endoscopic reduction and fixation.Study design Six consecutive subcondylar fractures were treated endoscopically. Intermaxillary fixation was used intraoperatively to aid in fracture reduction. A modified Risdon incision was used to gain access to the lateral ramus, and a modified retractor and endoscope were used for retraction and visualization. Fracture fixation was achieved with a 2-mm titanium plate and screws. Patients were evaluated clinically and radiographically for 6 months and functional, radiographic, and esthetic parameters were assessed at each time period (1, 2, 4, 12, and 24 weeks). RESULTS: All patients demonstrated a stable occlusion in the postoperative period and anatomic alignment of the condyle radiographically. By 1 month, maximum interincisal opening was 42.2 +/- 5.7 mm. There was no joint noise or temporomandibular joint (TMJ) pain postoperatively. Radiographs at each follow-up visit indicated the ramus height was maintained in most cases. There was minimal transient facial nerve paresis following surgery. Scar perception was considered acceptable by all patients. Operative times were acceptable as well. CONCLUSION: Endoscopic-assisted repair of subcondylar fractures is an additional tool for management of subcondylar fractures, however there is a steep learning curve based on this study. The technique allows good visualization of the fracture site for reduction through an incision with an acceptable cosmetic result.     

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.     

The use of an intermaxillary fixation screw for mandibular setback surgery.

PURPOSE: To assess skeletal stability after mandibular setback surgery with and without an intermaxillary fixation (IMF) screw. PATIENTS AND METHODS: The subjects were 40 patients with mandibular prognathism. The subjects underwent sagittal split ramus osteotomy with titanium plate fixation and were divided into 2 groups, 1 with and 1 without an IMF screw. A lateral cephalogram was done preoperatively, immediately after surgery, and 1 month, 3 months, and 6 months postoperatively. The 2 groups were then compared statistically. RESULTS: In the comparison of the time-course change between the 2 groups with repeated measure analysis of variance, there were significant differences in occlusal plane (between subjects, F = 2.517; df = 4; P = .0437) and convexity (between subjects, F = 4.048; df = 4; P = .0038). However, there was no significant difference in the other measurements. CONCLUSION: This study suggested that in most measurements, there was no significant difference between 2 groups with and without an IMF screw in time-course skeletal change. However, use of IMF screws was helpful for orthognathic surgery as a rigid anchor of IMF.     

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 extraoral vertical ramus osteotomy: plate fixation versus maxillomandibular/skeletal suspension wire fixation

The objective of this cephalometric study was to evaluate skeletal stability and time course of postoperative changes in 2 groups of mandibular prognathism patients following extraoral oblique vertical ramus osteotomy (VRO). One group (n = 22) received maxillomandibular fixation and skeletal suspension wires (MMF group) for a period of 8 weeks. In the other group (n = 22), the segments were rigidly fixed with plates and the patients were allowed to function immediately after surgery. Lateral cephalograms were taken on 5 occasions: immediately presurgical, immediately postsurgical, 8 weeks postsurgical, 6 months postsurgical, and 1 year postsurgical. During the first 8 weeks after surgery, the MMF group demonstrated posterior movement of the mandible, with an increase in mandibular plane angle, shortening of the rami, and dental compensations. Upon release of MMF and skeletal suspension wiring, a small anterior relapse tendency was observed, but the net setback 1 year after surgery was still greater than the actual surgical setback. In the plate fixation group, postoperative changes were mainly in the form of a small anterior relapse tendency in the range of 10% of the surgical setback. The results indicate that the use of plate fixation with VRO, while eliminating the inconvenience for the patient of several weeks of MMF and preventing the early side effects observed in the MMF group, also resulted in a more predictable surgical procedure, with excellent stability 1 year after surgery.     

内镜辅助下颌升支和髁颈骨折内固定

目的探讨内镜在下颌升支和髁颈骨折内固定术中的临床使用价值。方法11例下颌升支和髁颈骨折患者在内镜辅助下，用微型侧壁电钻和螺丝刀，经口内小型钛板内固定。结果全部病例面部皮肤均无明显手术瘢痕。术后1—15个月复查曲面断层X线片或螺旋CT三维重建，下颌骨骨折对位良好，10例恢复正常咬合关系，1例前牙轻度开猞，2例多处骨折患者术后轻度张口受限。结论在内镜辅助下行下颌升支和髁颈骨折内固定，可以避免损伤面神经，并避免遗留颌面部皮肤瘢痕，创伤小，效果好。     

Rehabilitation of patients with lower asymmetrical macrognathia

Unilateral subcondylar vertical osteotomy of the mandibular ramus was performed in 26 patients with asymmetric mandibular prognathism (AMP). 16 of 26 patients had temporomandibular joint (TMJ) symptoms before surgery. Asymmetric mandibular prognathism was combined with maxillary micro-retrognathism in 15 patients. Condyle position was evaluated by pre- and postoperative computed tomography (CT) data. Unlike mandibular sagittal split osteotomy with rigid fixation, the vertical subcondylar osteotomy with wire osteosyntheses allows to keep preoperative condylar head position on the side of hypertrophy and thus to prevent and eliminate TMJ symptoms postoperatively. Wire osteosynthesis promotes the most complete mechanism of adaptation and self-regulation of TMJ elements in surgical treatment of patients with asymmetric mandibular prognathism. All 26 patients had no TMJ symptoms postoperatively.     

Evaluation of soft tissue profile following intraoral ramus osteotomy in Chinese adults with mandibular prognathism

Twenty-five Chinese adults with mandibular prognathism were treated with either the intraoral vertical subcondylar osteotomy or the bilateral sagittal split ramus osteotomy. The patients were kept in maxillomandibular fixation for 6 to 8 weeks while osteosynthesis was achieved with the use of intraosseous wiring. Serial lateral cephalograms were taken presurgery and between 12 and 26 months postsurgery, and specific soft and hard tissue points were digitized on a computer. The mean mandibular setback postsurgically was 8.4 +/- 3.2 mm, with a 5.2-degree reduction in point A-nasion-point B angle. Posterior movement of pogonion, point B and the mandibular incisal edge was accompanied by posterior movement of 95% at soft tissue pogonion (r = .96), 89% at soft tissue point B (r = .83), and 67% at labrale inferius (r = .81), respectively. The correlation between changes in the labrale superius and mandibular setback appeared to be dependent on both the amount of mandibular setback and the degree of mandibular rotation during the setback surgery. The presently reported ratios of the soft tissue response to hard tissue movement vary from those reported in white patients by other researchers, which confirms the need for different ratios for different racial types.     

Three-dimensional evaluation of positional change of the condyle after mandibular setback by means of bilateral sagittal split ramus osteotomy

OBJECTIVE: The aim of this study was to evaluate condylar displacement in 3 dimensions by means of computed tomography after mandibular setback by sagittal split ramus osteotomy with rigid fixation and to compare these results with those from patients with mandibular advancement. STUDY DESIGN: Thirty Korean subjects with skeletal class III malocclusion who had undergone mandibular setback by sagittal split ramus osteotomy had computed tomographs taken. Tomographs were taken to evaluate the temporomandibular joint 1 month before and approximately 1 month after surgery. The position and angulation of the condyle were measured on axial or sagittal views. These measurements were analyzed to determine any correlations between the amount of mandibular movement and condylar displacement. RESULTS: The results of this study show that the condyle tends to move inferiorly and rotate inward on the axial view and backward on the sagittal view by a statistically significant amount. CONCLUSION: The positional change of the condyle after sagittal split ramus osteotomy was not correlated with the amount of the setback.     

Sensory impairment following sagittal split osteotomy for correction of mandibular retrognathism.

Sagittal split osteotomy of the mandibular ramus is performed in close proximity to the inferior alveolar nerve and may result in postoperative neurosensory disturbances. Intraoperative strain on the nerve and other complications in 25 patients undergoing bilateral sagittal split osteotomy were recorded. Neurosensory testing was carried out before and after surgery. The patients reported sensory disturbances in 54% of sites 4 days postoperatively and 42% and 34% of sites at 9 weeks and 6 months, respectively. Objective assessments showed an incidence of 34% at 4 days, 20% at 9 weeks, and 8% at 6 months. Sensory disturbance was closely related to the degree of intraoperative strain on the nerve.     

Stability of the Le Fort I osteotomy with anterior internal fixation alone: a case series.

PURPOSE: The purpose of this case series was to evaluate the late postsurgical stability of the Le Fort I osteotomy with anterior internal fixation alone and no posterior zygomaticomaxillary buttress internal fixation. PATIENTS AND METHODS: Sixty patients with maxillary vertical hyperplasia and mandibular retrognathia underwent a 1-piece Le Fort I osteotomy of the maxilla with superior repositioning and advancement or setback. A bilateral sagittal split ramus osteotomy for mandibular advancement was also performed in 22 patients. Stabilization of each maxillary osteotomy was achieved using transosseous stainless steel wires and/or 3-hole titanium miniplates in the piriform aperture region bilaterally, with no zygomaticomaxillary buttress internal fixation. (Twelve of the 60 identified patients were available for a late postoperative radiographic evaluation.) Lateral cephalometric radiographs were taken preoperatively (T1), early postoperatively (T2), and late postoperatively (T3) to analyze skeletal movement. RESULTS: These 12 patients (5 male, 7 female) had a mean age of 24.5 years at surgery. Mean time from surgery to T2 was 41.2 days; mean time from surgery to T3 was 14.8 months. One patient received anterior wire osteosynthesis fixation, while 11 patients received both anterior titanium miniplate internal skeletal fixation and anterior wire osteosynthesis fixation. Six patients underwent Le Fort I osteotomy with genioplasty, 1 patient underwent Le Fort I osteotomy with bilateral sagittal split ramus osteotomy, and 5 patients underwent Le Fort I osteotomy with bilateral sagittal split ramus osteotomy and genioplasty. These 12 patients all underwent maxillary superior repositioning with either advancement (11 patients) or setback (1 patient). Statistically significant surgical (T2-T1) changes were found in all variables measured. In late postsurgical measurements (T3-T2), all landmarks in the horizontal and vertical plane showed statistically significant skeletal stability. CONCLUSION: This case series suggests that anterior internal fixation alone in cases of 1-piece Le Fort I maxillary superior repositioning with advancement has good late postoperative skeletal stability.     

Stability after surgical-orthodontic correction of skeletal Class III malocclusion. I. Mandibular setback

Postsurgical stability of mandibular setback to correct mandibular prognathism was compared for three approaches: transoral vertical ramus osteotomy, bilateral sagittal split osteotomy with wire osteosynthesis and maxillomandibular fixation, and bilateral sagittal split osteotomy with rigid internal fixation via bone screws. In the transoral vertical ramus osteotomy group, the mean postsurgical change in chin position was almost zero, but nearly 50% of the patients did have clinically significant changes in chin position; two thirds of these movements were posterior and one third anterior. In the bilateral sagittal split osteotomy groups, the chin either stayed in its immediately postsurgical position or moved anteriorly. In one fourth of the patients who received maxillomandibular fixation and in nearly half of the patients who received rigid internal fixation, the chin moved forward more than 4 mm.     

Neurosensory disturbances one year after bilateral sagittal split mandibular ramus osteotomy performed with separators.

BACKGROUND: The most frequently performed osteotomy for correction of mandibular retrognathia is a bilateral sagittal split ramus osteotomy. Permanent neurosensory disturbance of the inferior alveolar nerve is one of the most frequently and severe complications. Many authors have reported this, but the incidence differs widely. In the recent literature, only four authors have reported a percentage of less than 10% after 1 year follow-up. OBJECTIVE: To determine the incidence of permanent neurosensory disturbance of the inferior alveolar nerve after bilateral sagittal split ramus osteotomy, and possible influences of the technique used. PATIENTS AND METHODS: A series of 109 patients is reported who underwent a bilateral sagittal split mandibular ramus osteotomy with the use of separators and without the use of chisels. The segments were hold by rigid transbuccal screw fixation. RESULTS: The incidence of neurosensory disturbances 1 year after surgery was 8.3%. CONCLUSION: The use of sagittal split separators without the use of chisels, may play an important role in the relatively low percentage of persistent hypoaesthesia of the inferior alveolar nerve.     

Comparison of methods to assess neurosensory alterations following orthognathic surgery

Orthognathic surgery may damage branches of the trigeminal nerve, resulting in postoperative neurosensory disturbances. Alterations may be due to surgical edema, stretching, or direct trauma to the nerve. Lack of a standard and objective method of assessment hinders efforts to study and/or reduce the incidence of neurosensory disturbances. This study compared three methods of assessing neurosensory disturbances in patients who underwent bilateral mandibular ramus sagittal split osteotomies. Forty patients (26 female, 14 male) ranging in age from 23 to 47 years participated in the study. All of the patients had bilateral mandibular ramus sagittal split osteotomies and were stabilized with rigid skeletal fixation. Neurosensory testing was performed prior to surgery, and at 2 weeks, 1 month, 3 months, 6 months, and 1 year following surgery. Methods of assessment included two-point discrimination, threshold to electrical stimulation, and somatosensory evoked potentials. Threshold to electrical stimulation and two-point discrimination were obtained by the two-alternate forced choice technique.(ABSTRACT TRUNCATED AT 250 WORDS)     

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。     

Prospektive kephalometrische Evaluation eines neuen dreidimensional justierbaren Osteosynthesesystems für die sagittale Ramusosteotomie

The aim of the study was the prospective cephalometric analysis of 58 patients who underwent sagittal split ramus osteotomy (SSRO). Stabilisation of the fragments was achieved with an adjustable monocortical bone fixation system. Lateral cephalograms were taken preoperatively, postoperatively, 6 months postoperatively, and 12 months postoperatively. The radiographs were digitised, and a computerised analysis was performed. The mean mandibular advancement was 8.5 mm with a mean relapse of 0.8 mm after 12 months (P < 0.05). The mean mandibular setback was 7.8 mm with a mean relapse of 1.2 mm after 12 months (P < 0.05). The results of the present study show a minimal relapse after mandibular advancement and setback for the SSRO and the new adjustable fixation system. Postoperative analysis reveals a safe intraoperative positioning of the condyles with subsequent prevention of an immediate relapse. The results after 12 months indicate sufficient long-term stability, although additional evaluations with results after 5 and 10 years are necessary for a final report.     

Changes of lateral soft tissue profile after surgical correction of mandibular prognathism

The lateral soft tissue profile was recorded in 10 patients with slight to moderate degrees of mandibular prognathism, preoperatively, and 6 weeks after subcondylar sliding osteotomy had been performed. The recording method was mechanical. Only small and insignificant profile changes were found in the submandibular and occlusal plane regions as well as in the ramus region. The only significant change of profile was found in the mandibular body region, probably as a result of firm connection between soft tissue and underlying distally moved bone. The lack of significant profile change in the osteotomy region was in accordance with subjective observations and was probably due to local remodelling and adaptation processes. The facial width was thus found to be unaltered 6 weeks postoperatively.     

髁突骨折手术治疗临床分析

目的:探讨髁突骨折手术治疗的不同术式、适应证、手术治疗程序,为临床治疗提供依据。方法:对112例髁突骨折临床资料进行分析,按照X线诊断、临床表现、骨折部位、移位程度、致伤时间等因素确定不同术式,观察其术后即期与远期效果,其中38例行传统切开复位内固定术,53例行不游离髁突的升支切开解剖复位术,18例行游离髁突和升支骨段倒置关节重建术,3例行游离髁突升支切开复位重建术。结果:各种不同的手术治疗方式均可获得较好的即期效果,但远期效果以不游离髁突的升支切开解剖复位术最佳。结论:对于大多数髁突骨折,尤其是中、低位骨折,脱位,移位或严重成角者以不游离髁突的升支切开解剖复位术效果最好。髁突粉碎骨折和陈旧骨折宜行游离髁突和升支骨段倒置关节重建术。髁突高位骨折宜行游离髁突升支切开复位重建术。     

3D CT evaluation of masseter muscle morphology after setback osteotomy for mandibular prognathism

OBJECTIVE: Following mandibular setback osteotomy, changes in the direction, length, and cross-sectional area of the masseter muscle were studied by means of computerized tomography (CT) images generated with a 3-dimensional (3D) reconstructive technique. STUDY DESIGN: Pre- and postoperative CT examinations were performed on 17 prognathic patients treated by sagittal split ramus osteotomy with rigid osteosynthesis and 13 patients treated by intraoral vertical ramus osteotomy without osteosynthesis. The pre- and postoperative masseter muscle direction and length were evaluated using 3D CT images observed from a lateral viewing angle. The cross-sectional area of the masseter muscle was first measured on an axial CT image of a selected slice level, following which the right-angle cross-sectional area of the muscle was revised using the measured area from the axial image. RESULTS: Postoperatively, anterior tilting of the masseter muscle was observed; however, masseter muscle length was unchanged. Three months postoperatively, a significant reduction in the cross-sectional area of the masseter muscle was seen. A tendency to revert back to the normal dimension was seen between 6 months and 1 year postoperatively. No significant difference was noted between the 2 surgical techniques. CONCLUSIONS: Three-dimensional computed tomography is an adequate imaging modality for masseter muscle evaluation. The results of this study suggest the masseter muscle may undergo reversible atrophy after mandibular setback osteotomy.