Skeletal stability following bilateral sagittal split osteotomy (BSSO) with and without condylar positioning device.

PURPOSE: The goal of this retrospective study was to investigate whether utilization of condylar positioning devices in comparison to the manual positioning technique has a favorable influence on skeletal stability after bilateral sagittal split osteotomy. PATIENTS AND METHODS: Lateral cephalometric radiographs of 49 patients who had undergone bilateral sagittal split osteotomy or bimaxillary surgery at the Universitiy Hospital of Aachen between 1993 and 2003 were evaluated with the aid of analysis software (Adda Keph version 3.0, JR - datentechnik, Leipzig, Germany). As a criterion for skeletal stability the postoperative changes of SNB angle and Wits appraisal were determined. In 10 of 28 patients with mandibular advancement and in 10 of 21 individuals with mandibular setback, the Luhr positioning device was used intraoperatively to reproduce the condylar position. Mandibular joints of the remaining patients were positioned manually. The results were statistically worked up by means of unrelated t test at P = .05. RESULTS: Neither in advancement nor in setback surgery did the positioning device technique result in better outcomes for postoperative changes of SNB angle and Wits appraisal. The confidence intervals rather suggest equivalence of the data in both groups. CONCLUSION: The use of positioning appliances does not lead to an improvement of skeletal stability. With the manual technique, equally stable results can be attained in advancement as well as in setback surgery.     

Intraoperative diagnosis of condylar sag after bilateral sagittal split ramus osteotomy

PURPOSE: To evaluate a method to identify condylar sag intraoperatively by clinical examination after bilateral sagittal split osteotomy (BSSO). METHODS: We prospectively studied 184 patients (121 female, 63 male) who had BSSO. The same surgeon operated all patients over a period of 15 months using the same technique. All patients had mandibular advancements. A standard condylar seating technique was used. The occlusion was evaluated at operation and 1 week later. RESULTS: Eighteen patients had an incorrect occlusion diagnosed during the operation after removal of the IMF. Peripheral condylar sag (type II) had developed in three of these patients. In 15 patients central sag was diagnosed. One-week postoperatively, three patients had a malocclusion as a result of condylar sag. CONCLUSION: Meticulous examination of the occlusion and an understanding of the occlusal changes secondary to condylar sag can reliably identify condylar sag intraoperatively. The use of suitable corrective measures during the primary operation can substantially reduce the postoperative complication rate of condylar sag.     

Modification of the bilateral sagittal split osteotomy (BSSO) in a study using pig mandibles

In a bilateral sagittal split osteotomy (BSSO) mechanical irritation of the inferior alveolar nerve (IAN) (e.g. by chiselling) should be avoided to prevent neural damage. A modification of the Obwegeser-Dal Pont operation technique was studied by splitting 100 pig mandibles ex vivo. An additional osteotomy at the caudal border of the mandible was used to facilitate the sagittal split by means of a locus of minor resistance. The chisel was inserted distal to the second molar and far away from the IAN. The mandible was split by torque. The modified technique reduced the required torque to split the mandible about 30% compared with the original technique (paired t-test, t(69) = −12.89; p < 0.05). 75% of all mandibles split by the modified technique were classified as bad splits compared with 100% using the original technique using the same protocol without the additional osteotomy.     

Proximal segment positioning in bilateral sagittal split osteotomy: intraoperative controlled positioning by a positioning splint

PURPOSE: Most techniques of proximal segment positioning hinder intraoperative condyle displacement. However, merely maintaining condylar position cannot optimize the preoperative condyle-disc-fossa relationship. This study attempts to optimize condylar position in the osteotomy patient. PATIENTS AND METHODS: A study group of 23 bimaxillary operated patients had intraoperative joint positioning by positioning splint and plates (9 Angle Class II, 14 Class III). After assessing the habitual and appraising the optimized condyle position on preoperative sonograms and magnetic resonance images, positioning splints were constructed as acrylic occlusal wafers in a semi-individual articulator. Set in occlusion before adaptation of positioning plates, they were intended to move the condyles into the calculated position. Eighteen bimaxillary operated control patients had conventional plate positioning according to the habitual occlusion (9 Angle Class II, 9 Class III). Clinical follow-up, axiography, or sonography was maintained for 24 months. Preoperative lateral cephalograms were scrutinized for horizontal and vertical joint spaces and compared with the immediate postoperative radiography. RESULTS: Postoperative Class II study group patients had less dorsal and more vertical joint space and Class III patients more dorsal and vertical space compared with the controls. The study group exhibited significantly less postoperative dysfunction compared with the control group (2-way analysis of variance: P <.021, F = 9.2, alpha =.05 significance level), disc dislocation prevalence was lower (P <.07, F = 9.2), postoperative changes in condylar translation were smaller (P <.014, F = 4.9), and 8% skeletal relapses versus 22% in the controls were seen. CONCLUSIONS: A proximal segment-positioning splint effectively positioned the condyle in the desired direction, but with considerable relapse, significantly reduced postoperative dysfunction, disc dislocations, changes to the condylar translation, and incidence of skeletal relapse at 24-month follow-up.     

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.     

Factors affecting neurosensory disturbance after mandibular bilateral sagittal split osteotomy.

PURPOSE: The current study evaluated the incidence of subjective neurosensory disturbances after bilateral sagittal split osteotomy (BSSO) in relation to gender, age, indication for osteotomy, magnitude of mandibular movement, degree of manipulation of the inferior alveolar nerve at operation, side of the mandible operated, and complications during and after surgery. PATIENTS AND METHODS: Thirty patients (60 sides) who had undergone a BSSO were followed up for 1 year after operation. The patients were classified into different groups according to gender, age, indication for osteotomy, magnitude of mandibular movement, degree of manipulation of the nerve, and complications during or after surgery. A self-administered questionnaire was used at every follow-up to evaluate the sensations in the mental region. RESULTS: A statistically significant positive correlation was found between subjective neurosensory loss and the patient's age (P = .039), magnitude of mandibular movement (P = .044), and degree of manipulation of the nerve (P = .0007). However, no significant correlation was found between disturbances of sensation and gender, indication for osteotomy, side of the operated mandible, or intraoperative and postoperative complications. Even if all patients evaluated their sensation as "normal" 1 year postoperatively, 31% of them reported slightly altered sensation in the mental region. CONCLUSIONS: After BSSO, a prolonged neurosensory deficit is strongly related to age, the intraoperative magnitude of mandibular movement, and the degree of manipulation of the inferior alveolar nerve. However, a long-term sensory loss is very rare, and patients seem to adapt to a mild neurosensory deficit and report sensory function as "normal" despite slightly altered sensation.     

Proximal segment positioning in bilateral sagittal split osteotomy: intraoperative dynamic positioning and monitoring by sonography.

PURPOSE: Most methods of condylar positioning merely maintain the preoperative condyle-fossa relationship and therefore produce similar prevalences of postoperative dysfunction. This study evaluates dynamic proximal segment positioning by intraoperative sonography versus the splint and plate technique discussed in a previous issue. PATIENTS AND METHODS: Condylar positioning was monitored by sonography alone in 30 bimaxillary operated patients (14 Angle Class II, 16 Class III), the control group had a splint and plate positioning in 23 patients (9 Angle Class II, 14 Class III). The clinical dysfunction index, prevalence of condylar translation, and disc dislocation were compared preoperatively and at 1, 6, and 12 months postoperatively. RESULTS: The postoperative range of motion did not disclose statistically significant differences between study and control group (Pearson's proportionality index r = 0.78, 2-way analysis of variance: P <.4, F = 4.4, alpha =.05 significance level). Sonographic placement allowed dynamic intraoperative monitoring of the condylar position and required an average of 5 minutes compared with 25 minutes for conventional positioning. Postoperative dysfunction prevalence was reduced 89% for Class II and 100% in Class III in the study group versus 50% for Class II and 100% for Class III in the control group (r = 0.45, P <.3, F = 9.3). Prevalence of disc dislocation was reduced 76% in Class II and 80% in Class III patients in the study group and 50% of Class II and 100% of Class III in the control group (r = 0.7, P <.48, F = 9.2). CONCLUSIONS: Comparable postoperative reduction of condylar translation and recovery, dysfunction, and disc dislocation was seen with use of both methods in a 1-year follow-up. The new technique allowed intraoperative real-time monitoring and dynamic correction and was safe, easier, and faster than conventional plate positioning.     

Stability of the mandible after bilateral sagittal split osteotomy: Comparison between positioning screws and plate

Relapse is one of the complications of orthognathic surgery. In this study, we compared the stability of mandibular bilateral sagittal split osteotomy by using two different methods of fixation. In Group 1, eight patients with prognathic mandible underwent BSSO and set back average of 6.0 mm. The method of fixation was positioning screws. In Group 2, eight patients with prognathic mandible underwent BSSO and set back average of 6.0 mm. The method of fixation was plate and monocortical screws. In Group 3, eight patients with retrognathic mandible underwent BSSO and advancement average of 6.0 mm. The method of fixation was positioning screws. In Group 4, eight patients with retrognathic mandible underwent BSSO and advancement average of 6.0 mm. The method of fixation was plate and monocortical screws. The results showed in terms of advancement that there was no significant difference between the groups after one year. However, in terms of set back, this study showed significant difference.     

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.     

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.     

Changes in condylar and joint disc positions after bilateral sagittal split ramus osteotomy for correction of mandibular prognathism

The effect of combined orthodontic and orthognathic treatment was studied retrospectively in 24 patients with skeletal class III malocclusions with mandibular hyperplasia, particularly the effect on temporomandibular joint (TMJ) disc position. The patients underwent preoperative orthodontic treatment, orthognathic surgery, and postoperative orthodontic treatment. The patients were studied clinically, radiographically with lateral cephalometric radiograph and MRI to locate the position of the TMJ disc in relation to the glenoid fossa. One patient had less pain after treatment, one lost abnormal joint clicking sounds after treatment. There were no TMJ symptoms in 20 of the 24 preoperatively and postoperatively. 48 sagittal MRI images showed that the disc length before treatment was 3.040–12.928 (mean 8.289 ± 2.028) and after treatment was 3.699–11.589 (mean 8.097 ± 1.966); results were not significant (p > 0.05). Maximum disc displacement before treatment was 6.090 (mean 1.383), after treatment it was 11.931 (mean 2.193); results were not significant (p > 0.05). The results suggest that combined orthodontic and orthognathic treatment (including bilateral SSRO and rigid internal fixation) can be used safely to correct skeletal class III malocclusion with mandibular hyperplasia without causing additional TMJ symptoms.     

Bilateral sagittal split osteotomy for correction of mandibular prognathism: long-term results.

PURPOSE: To identify the long-term maxillomandibular changes after surgical correction of mandibular prognathism using bilateral sagittal split osteotomy (BSSO). PATIENTS AND METHODS: Twenty patients who underwent BSSO to setback the mandible and had cephalometric radiographs taken preoperatively and postoperatively at 6 weeks, 1 year, and long-term follow-up (mean, 28 months). The cephalograms were traced and measured to determine the operative and postoperative changes. Correlation analyses were performed to see the relationship between the magnitude of setback and the amount of long-term postsurgical change at B point and pogonion. RESULTS: The mean surgical setback was 8.2 mm at B point and 8.8 mm at pogonion. The mean long-term horizontal relapse was 2.3 mm (28.0%) at B point and 3.0 mm (34.1%) at pogonion. Out of 20 patients, 12 (60.0%) relapsed horizontally greater than 2 mm at B point and 13 (65.0%) at pogonion. The mean vertical surgical changes showed downward displacement of B point (2.3 mm) and pogonion (2.0 mm). The mean long-term vertical relapse was 1.6 mm (69.6%) at B point and 1.7 mm (85.0%) at pogonion. CONCLUSION: There was no correlation between the magnitude of setback and the amount of relapse at B point and pogonion. However, there was significant correlation between the magnitude of vertical, downward surgical displacement and the amount of vertical relapse at B point and pogonion. The majority of the maxillofacial changes occurred within 1 year postoperatively.     

Mandibular remodeling after bilateral sagittal split osteotomy for prognathism of the mandible.

PURPOSE: To describe the postoperative remodeling changes in the mandible after bilateral sagittal split osteotomy to correct mandibular prognathism. PATIENTS AND METHODS: Twenty patients who underwent bilateral sagittal split osteotomy for the correction of mandibular prognathism were studied for postoperative remodeling changes within the mandible. The 6-week, 1-year, and long-term postoperative cephalometric mandibular tracings of 12 patients were superimposed using the fixation wires as the stable reference points to demonstrate the specific locations of the intrabony remodeling. RESULTS: There was a general direction of remodeling at the condylion and gonion anteriorly and superiorly, while the B point and pogonion did not show much change in remodeling. At the condylion, 60% and 40% of the cases showed significant horizontal and vertical remodeling, respectively. At the gonion, 50% and 55% of the cases showed significant horizontal and vertical remodeling, respectively. No correlation was found between the remodeling changes at condylion and gonion and the surgical movement or relapse at B point and pogonion. There was a significant correlation between the observed horizontal relapse at gonion and the horizontal remodeling changes at this point showing that the postoperative displacement of this point is a result of both positional translocation and remodeling changes. CONCLUSION: The results of this study show that there are intrabony remodeling changes that occur in the mandible after sagittal split osteotomy and that these continue for a long period of time in some patients. This remodeling occurred more in the condylar and gonial areas, while the chin remained relatively stable.     

Changes in condylar long axis and skeletal stability after bilateral sagittal split ramus osteotomy with poly-L-lactic acid or titanium plate fixation

This study was designed to assess skeletal stability after bilateral sagittal split ramus osteotomy (BSSO) and fixation with a poly-l-lactic acid (PLLA) plate, as compared to that after BSSO and fixation with a titanium plate, and to analyze the change in the condylar long axis after these procedures. The study group comprised 40 patients who had mandibular prognathism (20, titanium group; 20, PLLA group). The groups were randomized to show similar distributions of preoperative SNB. All patients underwent BSSO setback by the Obwegeser method. Fixation was done with bent titanium plates or bent PLLA plates, applied in a similar manner. Lateral, frontal, and submental-vertical cephalograms were analyzed preoperatively and postoperatively. The maximum mouth opening range and the incidence of temporomandibular disorders were also evaluated. There was no significant difference in the right condylar angle or width between the two groups, but the left condylar angle and width, gonial angle, and ramus inclination differed significantly between them (P<0.05). SNA, SNB, and ANB were similar in both groups. There was no significant difference between the groups in maximum mouth opening range or temporomandibular disorders. We conclude that the change in condylar angle after BSSO and fixation with a titanium plate is greater than that after BSSO and fixation with a PLLA plate, but skeletal stability related to the occlusion is similar for the two procedures.     

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.     

Quality of life several years after orthodontic-surgical treatment with bilateral sagittal split osteotomy

Abstract

Objective: To analyse oral health related quality of life (OHRQoL) several years after orthognathic treatment in patients who had Class II malocclusion with retrognathic mandible.

Material and methods: The initial study cohort comprised 151 patients with orthognathic treatment in 2007–2011. Of them, 77 patients (Group 1, mean age 41?years, range 19–71?years, 71% women) were clinically examined 6?years (range 4–8?years) after bilateral sagittal split osteotomy (BSSO). Group 2 included 24 former patients (mean 48?years, range 25–79?years, 50% women) who were willing to participate in a structured telephone interview. Group 3 consisted of 22 prospective patients (mean 35?years, range 18–56?years, 86% women) with a recent orthognathic treatment plan and awaiting treatment. QoL was assessed using two questionnaires, OHIP-14 and OQLQ.

Results: Based on responses, patients who had received orthognathic treatment (Groups 1 and 2) had better QoL than those awaiting treatment (Group 3).

Conclusion: Conventional orthognathic treatment, including mandibular advancement with BSSO, seems to have a positive long-term effect on patients’ QoL. More long-term follow-up studies are needed to assess the real impact of treatment on patients’ lives in the long run.     

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.