Bilateral Sagittal Split Osteotomy Procedures Research Articles

Does the modified inferior border osteotomy improve the surgical outcomes in bilateral sagittal split osteotomy?

BackgroundTo investigate the effect of lower border osteotomy on the lingual split pattern and IAN in BSSO procedures. Materials and MethodsThe study comprised 32 patients (64 operated sides) who underwent bilateral sagittal split osteotomy (BSSO) due to dentofacial abnormalities between the periods of April 2021 and April 2022. In the mandible, 32 sides (the conventional group) received standard BSSO surgery, while 32 sides (the modified group) additionally received lower border osteotomy. Data regarding the split difficulty of the mandibular in BSSO surgery and the recovery status of the inferior alveolar nerve (IAN) one year after surgery were obtained and evaluated from patient records. The fracture line was radiographically evaluated for the lingual split pattern following surgery. ResultsA statistically significant difference was observed in favor of the modified group when the mandibular split difficulty of the groups was compared (p=0.032). The split time of the modified group was found to be statistically shorter than the conventional group (p≤0.001). The mean numbness level of the modified group one year after surgery was statistically significantly lower than that of the conventional group (p = 0.019). Although there was no statistically significant difference between the two groups in terms of lingual fracture pattern, the rate of type 1 (87.5%) fracture was higher in the modified group compared to the other group (68.8%) (p=0.089). ConclusionThe lower border osteotomy performed in addition to the conventional BSSO surgery allows the split procedure easier and in a shorter time. The modification resulted in an increased incidence of type 1 lingual fracture pattern in the mandible. The neurosensory recovery capacity of the IAN in the postoperative period is higher in areas where lower-border osteotomies are performed.

Concomitant Extraction of Wisdom Teeth with Bilateral Sagittal Split Osteotomy (BSSO): A Case Series

Aim: Aim:To investigate the incidence of postoperative complications (including pain, nerve damage, swelling and infection) associated with the concomit an textraction of wisdom teeth at the time of bilateral sagittal split osteotomy procedures. Materials and Methods: A retrospective evaluation of eight patients who underwent concomitant removal of their lower wisdom teeth (either fully erupted, partially or fully bone impacted) at the time of their surgical procedure (Bilateral sagittal split osteotomy with/without LeFort 1 procedure/genioplasty). All patients presented to the Oral and Maxillofacial Surgery Department at Case Western Reserve University. Postoperative complications (including pain, nerve dysfunction, swelling and infection) were examined at regular follow-up appointments after their surgical procedure. Results: A total of eight patients were examined for post operative complications. All patients confirmed the presence of mild pain/discomfort/swelling in the short-term postoperatively.

A New Method to Design and Manufacture a Low-Cost Custom-Made Template for Mandible Cut and Repositioning Using Standard Plates in BSSO Surgery.

In this study, a new methodology for designing and creating a custom-made template for maxillofacial surgery has been developed. The custom-made template can be used both for cutting and repositioning of the mandible arches for executing a BSSO (bilateral sagittal split osteotomy) treatment. The idea was developed in order to give the possibility of using a custom-made template with standard plates, thus reducing long times, high costs and low availability of custom-made plates; this represents the proof of novelty of the proposed template, based on a well-established methodology. The methodology was completely developed in the CAD virtual environment and, after the surgeons' assessment, an in-vitro experiment by a maxillofacial surgeon was performed in order to check the usability and the versatility of the system, thanks to the use of additive manufacturing technologies. When computer-aided technologies are used for orthognathic surgery, there are significant time and cost savings that can be realised, as well as improved performance. The cost of the whole operation is lower than the standard one, thanks to the use of standard plates. To carry out the procedures, the proposed methodology allows for inexpensive physical mock-ups that enable the BSSO procedure to be performed.

Post-BSSO condylar position stability: a comparison of miniplate and lag screw fixation

BackgroundThis study was conceived to assess the postoperative stability of condylar position following fixation with miniplates and lag screws after bilateral sagittal split osteotomy (BSSO).MethodsThis retrospective study included a cohort of 20 patients undergoing BSSO using the Obwegeser-Dal Pont modification. The bony segments were stabilized using either miniplates with two 2.0-mm monocortical screws per segment or three 2.0-mm bicortical lag screws along the mandible’s superior border. Pre- and postoperative (7-day interval) spiral computed tomography scans were conducted to assess skeletal changes across both groups. Data analysis employed Wilcoxon signed-rank and Wilcoxon rank-sum tests (α = 0.05).ResultsNo statistically significant difference was observed between the pre-and postoperative condylar position parameters (P>0.05). However, the lag screw group showed a marginal significant increase in the left condyle’s angulation (preoperative: 24.83 ± 6.37 vs. postoperative: 32.5 ± 4.93; P = 0.04). Changes in condylar height, length, and width were not statistically significant before and after BSSO in either groups (P>0.05). Nor was any statistically significant difference found between the miniplates and lag screws groups regarding condylar position parameters (P>0.05).ConclusionThe results indicated that both lag screw and miniplate fixation methods can be effectively employed in BSSO procedures without impacting condylar position parameters. Thus, either fixation method can be chosen depending on factors such as the surgeon’s preference and clinical outcomes.

Surgical Management of Laterognathia with Bilateral Sagittal Split Osteotomy: A Serial Case Report

Introduction: Laterognathia is characterized by the mandibular deviation to one of the sides affected which often caused by unilateral overgrowth of the mandible and age-related adaptive remodeling changes in the temporomandibular joint (TMJ) that affected masticatory function and aesthetics. The aim of this serial case report is to discuss the surgical management for laterognathia with bilateral sagittal split osteotomy (BSSO) on a clinical case of asymmetrical dentofacial deformity due to an excessive mandibular unilateral laterognathia. Case Report: This case report contains two cases of mandibular laterognathia. Both of our patients underwent a corrective procedure with bilateral sagittal split ramus osteotomy (BSSO) that performed mandibular setback and rotation. Post-operative follow-up showed the patient was in good condition and no complications were noted. Conclusion: The mandibular setback and rotation procedure can be performed with a bilateral sagittal split ramus osteotomy (BSSO). Significant improvement of laterognathia in occlusion, masticatory function, and facial appearance was achieved by surgical management with BSSO procedure. Keywords: laterognathia, bilateral sagittal split osteotomy, mandibular setback.

Development of the Customized Asymmetric Fixation Plate to Resist Postoperative Relapse of Hemifacial Microsomia Following BSSO: Topology Optimization and Biomechanical Testing.

Hemifacial microsomia (HFM), one of the most common congenital facial anomalies, was usually treated with the bilateral sagittal split osteotomy (BSSO) procedure to correct the asymmetric appearance and malocclusion of the mandible. However, the frequent post-operative relapse incidents would lead to the restoration of the mandibular segment to its preoperative position and failure of the BSSO procedure. In this study, a customized asymmetric fixed plate (CAF plate) was developed to resist relapse due to hemifacial microsomia occlusal forces and the different muscular traction forces on both sides of the mandible. For the actual HFM case in this study, the reconstructed mandibular segmental bone model was fixed using BSSO with a rectangular plate (the original CAF plate appearance) in the topology optimization analysis. With the topology optimization technique, the CAF plate was designed with a lightweight profile and excellent structural strength in consideration of the HFM asymmetrical muscle traction and occlusal force. Using biomechanical simulations, the von-Mises stress and CAF plate mandibular segment displacement and the miniplate were compared to evaluate which had superior relapse resistance. In the in-vitro biomechanical test, a fatigue force of 250,000 cycles and a constant muscle traction force were applied to the HFM mandibular model, which was fixed with the CAF plate fabricated using metal 3D printing (selective laser melting, SLM) to obtain the mandibular segment displacement as a relapse assessment. The topology optimization analysis showed that the CAF plate has the best characteristics, light weight and structural strength with 30% volume retention. The biomechanical analysis showed that the maximum von Mises stress of the mini-plate was 2.71 times higher than that of the CAF plate. The relapse displacement of the mandibular segment fixed with the mini-plate was 1.62 times higher than that fixed with the CAF plate. The CAF plate ability to resist relapse was confirmed by the biomechanical testing results so that only 0.29mm of recurrence displacement was observed in the mandibular segment. The results indicated that the CAF plate structural strength and resistance to relapse was significantly better than that of the mini-plate. This study developed a customized asymmetric fixation plate for hemifacial microsomia, integrating topology optimization, metal 3D printing, and in vitro biomechanical testing to resist occlusal forces and differential muscle traction on both sides of the mandible to reduce relapse and improve fixation stability.

Risk factors for lower border notching after bilateral mandibular sagittal ramus advancement: three-dimensional evaluation

Bilateral sagittal split osteotomy (BSSO) mandibular advancement can cause mandibular lower border notching (MLBN). The objective of this study was to calculate the incidence of MLBN and identify risk factors. This single-centre, retrospective study was performed between January 2018 and November 2020, in the Maxillofacial Surgery Department, Centre Hospitalier Universitaire, Caen. Patients who underwent BSSO advancement and had cone beam computed tomography (CBCT) scans obtained preoperatively, immediately postoperative (within 1 week), and late postoperative (≥1 year) were included. Measurements were made on the CBCT images. A total of 113 patients (226 operated sides) were enrolled. Mean age at the time of surgery was 17 years; 66.4% of patients were female and 33.6% were male. MLBN was observed on 35 operated sides (15.5% of sides). Advanced age (P = 0.002) and the degree of mandibular advancement (P = 0.008) were determined to be risk factors for developing MLBN. Sex, the operated side, third molar removal, and genioplasty were not associated with an increased occurrence of MLBN. Older patient age at the time of surgery and the requirement for a large advancement should be taken into consideration by the surgeon in order to reduce the risk of MLBN by using a modified BSSO procedure or bone grafting.

Management of A Bad Split Complication: A Systematic Review

Introduction: Bad split is one of the well-known intra-operative complications that occur during the bilateral sagittal split osteotomy (BSSO) procedure, which is a rehabilitation procedure for patients with mandibular deformities. The prevention of further post-surgery complications required sufficient management of bad split complications. Objective: This study aimed to analyze the management of bad split complications during a BSSO procedure. Methods: The literature review was conducted in the form of library research in the field of bad split complications' management by a BSSO based on the Preferred Reporting Items for Systematic Reviews (PRISMA). Related studies were found through using a manual search using Pubmed, ScienceDirect, Ebscohost, Scopus, Medline, Embase, and Web of Science, among other search engines. The inception of incorporation standards, the process of data extraction, and the determination of the risk of bias were carried out by the authors. The process of data screening was conducted by applying the inclusion and exclusion criteria. Results: This paper systematically reviewed seven related studies, four of which were case series and two of which were cross-sectional. The utilization of additional osteosynthetic plates was revealed throughout the extraction process as the most acquainted course of action to manage the bad split complications during the BSSO procedure. Conclusion: The osteosynthetic plate and miniplate application with bicortical or monocortical screws were exposed as the most used treatment for bad split complications.

Jawline Contouring Through an Intraoral Approach in the Context of Bilateral Sagittal Split Osteotomy: A Proof-of-Concept Report

This report describes a technique to suspend the submandibular space (SS) through an intraoral approach in the context of a bilateral sagittal split osteotomy (BSSO), thus improving the jawline contour and achieving a neck-rejuvenating effect. A sample of 6 consecutive patients referred for orthognathic surgery who also sought neck rejuvenation and contouring surgery was selected to implement the technique. The following measurements were used to evaluate the procedure: patient satisfaction with a visual analog scale, photographic assessment, additional operative time, and complications related to the procedure. The average patient age was 47years (range, 38 to 57yr). Three patients were women and 3 were men. All patients were highly satisfied with the results achieved at the jawline. No surgical complications occurred in any case. There was an average increase of only 5minutes in total operative time for each side. Suspension of the SS through an intraoral approach is an effective, well-tolerated, and technically straightforward method for neck contouring in patients in whom a BSSO procedure is foreseen.

Piezosurgery for Sagittal Split Osteotomy: Procedure Duration and Postoperative Sensory Perturbation

To evaluate piezosurgery for bilateral sagittal split osteotomy (BSSO) for its duration and inferior alveolar nerve (IAN) perturbation. In this prospective randomized study, the authors evaluated 100 BSSO procedures in 50 patients. Piezoelectric (group I) and conventional (group II) osteotomies were carried out on each side of the mandible of a patient by 2 specialists. The surgeons had at least 1year of experience using piezosurgery. The period from incision to complete splitting of the mandibular bone was recorded (ie, procedure duration). The intraoperative status (visibility and relocation) of the IAN also was recorded. The neurosensory function of the IAN was measured by the 2-point discrimination threshold and static light touch methods before surgery and postoperatively (1, 3, and 6weeks and 6 and 12months). Parameters were compared between the test groups by the paired t, nonparametric Wilcoxon, or χ2 test. Intergroup comparison showed the mean duration of osteotomy was significantly shorter for group I (17±6 vs 25±9minutes; P<.001). The rate of intraoperative exposures of the IAN was slightly lower for group I (68%) compared with group II (81%). However, the difference was not relevant. Neurosensory disturbance and recovery of the IAN did not differ between groups. Piezoelectric osteotomy requires considerably less time than conventional mechanical approaches, but shows no advantage in preventing neurosensory perturbation.

Intraoperative Computed Tomography in Bilateral Sagittal Split Osteotomy.

The objective of the study was to show the importance of intraoperative computed tomography as an aid for ensuring inferior alveolar nerve safety during bilateral sagittal split osteotomy. This study included ten patients who underwent bilateral sagittal split osteotomy procedure. All patients were treated for orthognathic reasons. The unerupted lower third molars, if present, were removed at least 6months prior to Sagittal Split Osteotomy. The Sagittal Split Osteotomy surgical technique was previously described in detail. Each patient underwent computed tomography with an Artis Zeego multi-axis system (Siemens AG, Healthcare Sector, Henkestrasse 127 D-91052 Erlangen, Germany) at the beginning of the operation and immediately after placement of the osteosynthesis plates and screws. The neurosensory tests consisted of a light touch test using the 5.07/10-g Semmes Weinstein monofilament (Stoelting Co, Wood Dale, IL), and patient self-reporting. Eight (80%) patients presented with hypoesthesia of lower lip at 6weeks follow up. At 6month follow up only two patients (20%) presented with diminished sensation in the lower lip. Labial sensibility was normal in all patients at the last follow-up visit. Intraoperative computed tomography enables immediate assessment of treatment and the option to modify the treatment if necessary. Our results indicate that intra-operative computed tomography would be a helpful procedure during orthognathic surgery to improve the postoperative health of the inferior alveolar nerve.

Attachment Rate of the Inferior Alveolar Nerve to Buccal Plate During Bilateral Sagittal Split Osteotomy Influences Self-Reported Sensory Impairment

This study was aimed to investigate a modified buccal osteotomy technique and whether the integrity of the lingual part of the lower border influences the attachment of the neurovascular bundle to the proximal segment of the mandible during a sagittal split osteotomy without increasing the number of bad splits. The presence of self-reported sensibility disturbance in the lower lip at the last follow-up visit was assessed. This study included 220 and 133 patients with bilateral sagittal split osteotomy undergoing the classical and the new modified buccal osteotomy techniques, respectively. In the new technique, the lower border is divided into a lingual fragment that remains incorporated in the tooth-bearing fragment and a buccal fragment that comes with the proximal fragment (buccal plate). In the classical technique, the inferior alveolar nerve was attached to the proximal segment of the mandible in more than one third of operation sites (36.36% on the right and 40.91% on the left) compared with less than one fourth of the operation sites using the new technique (9.73% on the right and 23.01% on the left). The overall figure of self-reported changed sensibility was 09.40% (12/128) in the new technique compared to 15.12% in the classical technique. We present a suitable improvement to the classical buccal osteotomy technique that allows less manipulation and injury of the inferior alveolar nerve with consequent reduction in self-reported postoperative changes in lower lip sensation

Skeletal stability after mandibular advancement in bilateral sagittal split osteotomies during adolescence

Bilateral sagittal split osteotomy (BSSO) is the most frequently performed surgery for correcting mandibular retrognathia. Few studies have reported the use of BSSO in young patients, as growth may cause relapse. The aim of the present study was to determine the amount of relapse after performing BSSO in patients aged less than 18 years. Patients who had a mandibular advancement by BSSO surgery between January 2003 and June 2008 were evaluated. Eighteen patients were treated before the age of 18 years and compared with patients treated at 20–24 years of age. Cephalometric radiographs were used to determine the amount of relapse. For patients aged less than 18 years, the mean horizontal relapse after 1 year was 0.5 mm, (10.9% of perioperative advancement). For patients aged 20–24 years, the mean relapse was 0.9 mm, (16.4% of perioperative advancement). There were no significant differences between the age groups (p > 0.05). In conclusion, the BSSO procedure is a relatively stable procedure, even during adolescence.

Impact of the mandibular divergence on the position of the inferior alveolar nerve and mylohyoid nerve: a computed tomography study and its relevance to bilateral sagittal split osteotomy

Bilateral sagittal split osteotomy (BSSO) is the most common procedure used to treat mandibular deformities. BSSO procedures include the Epker technique and the Dal Pont technique which are the most frequently used. Because of the intramandibular pathway of the inferior alveolar nerve (IAN), neurosensory disturbance of the lower lip and chin is the most common complication of BSSO. This study performed quantitative measurements from computed tomographic (CT) data obtained on dry human mandibles. The main aim of the study was to evaluate if mandibular divergence can predict the position of the IAN and the mylohyoid nerve (MHN) to prevent nerve injury. After CT and 3D reconstruction of 65 dry mandibles, 30 measurements were made on 3 planes for each hemi-mandible. This allowed analysis of the IAN and MHN pathways. Three groups of hemi-mandibles were created depending on their divergence, and a statistical analysis was performed. Eight out of the 30 measurements showed a significant difference among the 3 groups. There was no significant difference for the remaining 22 measurements. The IAN seems to have a more superior position in the groups of mandibular hypo- and hyper-divergence. Orthognathic surgeons should use a more superficial retromolar bone incision in these cases. Finally, the Epker technique would be safer for preserving the MHN in normo- and hypo-divergent patients.

Neurosensory disturbances one year after bilateral sagittal split osteotomy of the mandibula performed with separators: A multi-centre prospective study

Bilateral sagittal split osteotomy (BSSO) is an effective and commonly used treatment to correct mandibular hypo- and hyperplasia. Hypoesthesia of the inferior alveolar nerve (IAN) is a common complication of this surgical procedure. This prospective multi-centre study aimed to determine the incidence of neurosensory disturbances of the IAN after BSSO procedures performed without the use of chisels. Our study group comprised 158 patients, with a follow-up period of 1 year, who underwent BSSO (with or without Le Fort I) that incorporated the use of sagittal split separators and splitters but no chisels. The percentage of BSSO split procedures that resulted in IAN damage was 5.1%. The percentage of patients (without genioplasty) who experienced IAN damage was 8.9%. The concomitant genioplasty in combination with BSSO was significantly associated with hypoesthesia. Peri-operative removal of the wisdom tooth or a Le Fort I procedure did not influence post-operative hypoesthesia. We believe that the use of splitting forceps and elevators without chisels leads to a lower incidence of persistent post-operative hypoesthesia 1 year after BSSO of the mandible, without increasing the risk of a bad split.

Comparative Evaluation of Vertical Body Osteotomy and Sagittal Split Osteotomy for Mandibular Corpus Distraction: Is There a Rationale for the New Technique?

Comparative Evaluation of Vertical Body Osteotomy and Sagittal Split Osteotomy for Mandibular Corpus Distraction: Is There a Rationale for the New Technique?

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Regression models for patient-reported measures having ordered categories recorded on multiple occasions

The article reviews proportional and partial proportional odds regression for ordered categorical outcomes, such as patient-reported measures, that are frequently used in clinical research in dentistry. The proportional odds regression model for ordinal data is a generalization of ordinary logistic regression for dichotomous responses. When the proportional odds assumption holds for some but not all of the covariates, the lesser known partial proportional odds model is shown to provide a useful extension. The ordinal data models are illustrated for the analysis of repeated ordinal outcomes to determine whether the burden associated with sensory alteration following a bilateral sagittal split osteotomy procedure differed for those patients who were given opening exercises only following surgery and those who received sensory retraining exercises in conjunction with standard opening exercises. Proportional and partial proportional odds models are broadly applicable to the analysis of cross-sectional and longitudinal ordinal data in dental research.

Semirigid Fixation of Mandible and Maxilla in Orthognathic Surgery

Although the use of rigid fixation of bony segments in orthognathic surgery has become a standard of care, the question remains, 'With use of rigid fixation has stability of common orthognathic surgical procedures improved?' Because of the problems with various methods of osteosynthesis for the osteotomies commonly used in orthognathic surgery, we have developed our own way of semirigid fixation method to stabilize the osteotomized fragments for bone healing with enough flexibility to avoid the problems arising from absolute rigid fixation. The purpose of this article is to review the existing data to determine whether our method of semirigid fixation yields enough short-term and long-term stability after orthognathic surgery procedures. The study was designed as a retrospective trial. A total of 23 patients with double jaw surgery and 12 patients with mandibular set back surgery were reviewed. Preoperative lateral cephalometric radiographs obtained 1 month before the surgery, early postoperative cephalometric radiographs obtained after intermaxillary fixation was opened and late postoperative cephalometric radiographs were evaluated. Pog-McNamara vertical (mm) was used to measure the anteroposterior movement of mandible. Facial axis (degrees) was used to measure the vertical movement of the anterior part of the mandible. A-McNamara vertical (mm) was used to measure the anteroposterior movement of maxilla. Maxillary height (degrees) was used to measure rotational movement of the osteotomized maxillary segment in vertical dimension. The raw data obtained from cephalometric analysis were evaluated by using the computerized statistical program SPSS version 11.5 for Windows. The differences in linear and angular measurements between time intervals were tested for statistical significance, using repeated measures analysis of variance. A value of P < 0.05 was considered significant. None of the patients had infection at maxillary osteotomy side. Unilateral local infection at osteotomy side was seen in only one patient after double jaw surgery. Condylar malpositioning was not observed in any of the patients. Although postoperative maxillaomandibular fixation with elastics was applied routinely to all patients for 15 days, none of the patients had complaint related with temporomandibular joint discomfort, such as pain, restricted joint motion, etc. There is significant difference in anteroposterior movement of mandible in all time intervals. In terms of facial axis, the differences at T1 and T2 and at T2 and T3 are significant, while the difference at T1 and T3 is not significant. There is significant difference in anteroposterior movement of maxilla in all time intervals. In terms of maxillary height, the differences at T1 and T2 and at T2 and T3 are significant, while the difference at T1 and T3 is not significant. Method of semirigid fixation with 2 plates for maxillary fixation and 2 screws for mandibular fixation provide enough stability after LeFort I and bilateral sagittal split osteotomy procedures where mainly anteroposterior linear displacements were performed. There was no significant clinical short-term or long-term relapse. Stability in rotational movements needs to be further evaluated.

The Medial Surface of the Mandible as an Alternative Source of Bone Grafts in Orthognathic Surgery

A technique of harvesting bone grafts from the medial surface of the angle of the mandible during a bilateral sagittal split osteotomy procedure is described. In 20 patients who underwent mandibular setback for the correction of class III dentofacial deformities, bone grafts were harvested from the medial mandibular angle and used for simultaneous augmentation of the midface or for interpositioning and stabilization of the maxilla after LeFort I maxillary anterior or inferior repositioning. The mean postoperative follow-up was 6 months (range, 3-12 months). No complications occurred, and postoperative morbidity was similar to that encountered by patients who undergo sagittal split osteotomy without bone harvest. The technique described shows that the medial mandibular angle is a suitable donor site for membranous bone grafts in patients who undergo sagittal split osteotomy.