Bilateral Sagittal Split Osteotomy Setback Research Articles

Assessment of Mandibular Canal Using Cone-Beam Computed Tomography (CBCT) and Its Relevance in Post-Operative Neurosensory Disturbances Following Bilateral Sagittal Split Osteotomy Setback.

Damage to the inferior alveolar nerve (IAN) during bilateral sagittal split osteotomy (BSSO) causesneurosensory disturbances (NSD) of the lower lip and chin. The study aims to investigate the pre-operative position and course of the mandibular canal using cone-beam computed tomography (CBCT) and orthopantomogram (OPG) and compare if there is any difference in NSD following the BSSO setback procedure. This is an observational study. This study was conducted in the Department of Oral and Maxillofacial Surgery, Mar Baselios Dental College, Kothamangalam, from November 2017 to October 2019. Thirty patients undergoing BSSO setbacks are selected based on the inclusion and exclusion criteria and randomly grouped into two groups - group A (15) andstudy group B (15). OPG was done for both groups as it was required during surgical orthodontic evaluation and preoperative assessment of the mandibular canal was done using CBCT in group B. Neurosensory assessment was done in all the patients and compared the results. NSD were reported in all the patients on the first postoperative day. The correlation between subjective and objective evaluation showed absolute coincidence but nearly all the patients returned to their presurgical situation within six months in group B and one year in group A who had NSD problems. From the study, it can be concluded that a CBCT scan is a useful and reliable modality in the pre-operative evaluation of the mandibular canal in patients undergoing BSSO setback procedures, which helps to improve the patient's post-operative care and quality of life.

Three Different Fixation Modalities following Mandibular Setback Surgery with Sagittal Split Ramus Osteotomy: A Comparative Study using Three-dimensional Finite Elements Analysis.

The provision of sufficient stability after maxillofacial surgery is essential for the reduction of complications and disease recurrence. The stabilization of osteotomized pieces results in rapid restoration of normal masticatory function, reduction of skeletal relapse, and uneventful healing at the osteotomy site. We aimed to compare qualitatively stress distribution patterns over a virtual mandible model after bilateral sagittal split osteotomy (BSSO) bridged with three different intraoral fixation techniques. This study was conducted in the Oral and Maxillofacial Surgery Department of Mashhad School of Dentistry, Mashhad, Iran, from March 2021-March 2022. The mandible computed tomography scan of a healthy adult was used to generate a 3D model; thereafter, BSSO with a 3mm setback was simulated. The three following fixation techniques were applied to the model: 1) two bicortical screws, 2) three bicortical screws, and 3) a miniplate. The bilateral second premolars and first molars were placed under mechanical loads of 75, 135, and 600N in order to simulate symmetric occlusal forces. Finite element analysis (FEA) was carried out in Ansys software, and the mechanical strain, stress, and displacement calculations were recorded. The FEA contours revealed that stress was mainly concentrated in the fixation units. Although bicortical screws presented better rigidity than miniplates, they were associated with higher stress and displacement readings. Miniplate fixation demonstrated the most favorable biomechanical performance, followed by fixation with two and three bicortical screws, respectively. Intraoral fixation with miniplates in combination with monocortical screws can serve as an appropriate fixation arrangement and treatment option for skeletal stabilization after BSSO setback surgery.

The Relation Between Mandibular Relapse and the Postoperative Mandibular Ramus Rotation Following BSSO Setback.

This retrospective study aimed to determine the angulation changes of the proximal segment following bilateral sagittal split osteotomy (BSSO) setback and its correlation with the amount of immediate postoperative surgical movement. The correlation between postoperative relapse of the distal and proximal segment at six months postoperatively was also evaluated. The CBCT-generated lateral cephalometric images of 39 patients who underwent BSSO setback with or without Le Fort I osteotomy were evaluated preoperatively (T0), immediately postoperative (T1), and six months postoperatively (T2). The mean surgical setback was 7.28 ± 4.45mm at B point. The proximal segment's immediate postoperative mean posterior rotation was 2.13 ± 3.59degrees. Six months after the operation, the mean distal segment relapse was 0.89 ± 3.03mm at B point. The proximal segment relapse was 0.81 ± 1.63 degrees. A significant moderate correlation was found (P < 0.05) between the surgical movement and the immediate postoperative proximal segment rotation and between the surgical movement and the distal segment relapse. A significant correlation was found between the distal segment relapse and the average and left proximal segment relapse. There was no significant correlation between immediate postoperative proximal segment rotation and distal segment relapse. The immediate postoperative posterior rotation of the proximal segment had a negligible effect on mandibular relapse. The amount of surgical movement, on the other hand, was more related to distal segment relapse. The intraoperative proximal segment rotation should thus be minimized in cases with a significant surgical setback.

Neurosensory deficit of inferior alveolar nerve after bilateral sagittal split osteotomy, advancement versus setback: An observational study

Aim: The aim of this study was to compare the incidence of inferior alveolar sensory deficits, its association with various intraoperative nerve encounter status and the possible outcome of neurosensory deficits (NSDs) of the bilateral sagittal split osteotomy (BSSO) advancement, and setback procedures. Materials and Methods: This was an observational study among the oral and maxillofacial surgeons of south India who had expertise in the field of orthognathic surgery. A self-administered questionnaire (SAQ) with closed-ended answers was prepared using Google Forms (Google Inc.), pretested, and was sent to the prospective participants selected by convenience sampling through various social media outlets. A total of 1600 participants were included, and the sample size was estimated by the formula = 4pq/d2 and assessed 800 cases each of BSSO setback and advancement surgeries. Since the study focused on the NSD of the inferior alveolar nerve (IAN) post-BSSO, the advancement procedures, setback procedures, and various nerve encounter statuses were considered the variables. All the study procedures were performed as per the ethical guidelines laid down by the Declaration of Helsinki (October 2013) after approval by the Institutions Human Ethics Committee (IHEC), Rajah Muthiah Medical College, Annamalai University. Results: Chi-squared test was used to assess the qualitative variables. The incidence of NSDs was 17.7% in the setback cases and with respect to advancement, the NSD was 15.1%, P < 0.08 indicating no statistically significant difference. When comparing the independent nerve encounter status and NSDs between the groups, the cases where the nerve got transected post osteotomy, necessitating repair as well as those needing dissection due to its presence in the proximal fragment presented with a higher incidence of NSDs which was clinically and statistically significant, P < 0.001. Conclusion: No significant difference was observed in the NSD after mandibular sagittal split advancement and setback procedures. The status of the IAN intraoperatively can influence the incidence of postoperative prolonged IAN NSDs.

Postoperative changes in the pharyngeal airway space through computed tomography evaluation after mandibular setback surgery in skeletal class III patients: 1-year follow-up

BackgroundThis study evaluated the pharyngeal airway space changes up to 1 year after bilateral sagittal split osteotomy mandibular setback surgery and bimaxillary surgery with maxillary posterior impaction through three-dimensional computed tomography analysis.MethodsA total of 37 patients diagnosed with skeletal class III malocclusion underwent bilateral sagittal split osteotomy setback surgery only (group 1, n = 23) or bimaxillary surgery with posterior impaction (group 2, n = 14). Cone-beam computed tomography scans were taken before surgery (T0), 2 months after surgery (T1), 6 months after surgery (T2), and 1 year after surgery (T3). The nasopharynx (Nph), oropharynx (Oph), hypopharynx (Hph) volume, and anteroposterior distance were measured through the InVivo Dental Application version 5.ResultsIn group 1, Oph AP, Oph volume, Hph volume, and whole pharynx volume were significantly decreased after the surgery (T1) and maintained. In group 2, Oph volume and whole pharynx volume were decreased (T2) and relapsed at 1 year postoperatively (T3).ConclusionIn class III malocclusion patients, mandibular setback surgery only showed a greater reduction in pharyngeal airway than bimaxillary surgery at 1 year postoperatively, and bimaxillary surgery was more stable in terms of airway. Therefore, it is important to evaluate the airway before surgery and include it in the surgical plan.

Are we able to predict airway dimensional changes in isolated mandibular setback?

The goal of this study was to determine whether a relationship exists between the amount of mandibular setback and the amount of airway dimensional changes. Records and cone beam computed tomography (CBCT) of patients who had undergone isolated bilateral sagittal split osteotomy setback between January 1, 2013 and March 16, 2020 at a single institution were reviewed retrospectively. The primary outcome variable was upper airway volume dimension change, and the predictor variable was the magnitude of mandibular setback as measured by six different methods. Thirty-one patients were included in the study, with a mean mandibular setback ranging from 1.41 mm to 6.11 mm. None of the predictor variables showed an association with oropharyngeal (P = 0.54) or hypopharyngeal (P = 0.33) volume. Stepwise regression analysis failed to show any significant relationships. Similarly, there was no statistically significant association between any of the predictor variables and oropharyngeal (P = 0.44) or hypopharyngeal (P = 0.74) minimum axial area. The results showed that no correlation exists between the magnitude of mandibular setback and the amount of static airway dimensional changes; therefore, it may not be possible to predict whether obstructive sleep apnea will develop following mild to moderate mandibular setback based upon CBCT measurements.

Evaluation of Cephalometric Changes and Its Relation to Changes in Patients' Quality of Life After Mandibular Setback Surgery.

To find out if a relationship exists between the different cephalometric changes and the perception of patients before and after Bilateral Sagittal Split Osteotomy (BSSO) setback surgery. Sample consisted of 28 patients (mean age 23.78 ± 1.36years), Male:Female = 1:1.3, with a median follow-up of 10 ± 1.8months, with skeletal class III malocclusion treated with BSSO setback surgery. Pre- and post-surgery lateral cephalograms were analysed. The Oral Health Impact Profile (OHIP) questionnaire was used to assess the patients' quality of life after surgery. Cephalometric data were then correlated with the questionnaire results. The psychological and social aspects of OHIP questionnaire were most affected. The most significant correlation between OHIP score change and cephalometric parameters was found with reduction of 'lower lip protrusion'; and significantly positive correlations were with increase in ANB angle and reduction in values of SND angle, N-B distance, lower lip length, lower facial height, mentolabial angle and angle of facial convexity. A significant relationship exists between the subjective and objective parameters which should be considered while planning for orthognathic surgery. Results of this study could be beneficial, helping the clinicians, to emphasise on specific cephalometric variable with the patient-specific expectations.

Treatment effect of combined surgical maxillary expansion and mandibular setback in skeletal class III

The purpose of this case report is to describe and discuss a combined surgical and orthodontic technique for the management of transverse maxillary deficiency and mandibular prognathism in the treatment of skeletal Class III malocclusion in a mature patient. Skeletal Class III malocclusion can present with maxillary deficiency or retrognathism, mandibular excess or prognathism, or a combination. The maxillary arch is narrow and often requires expansion. A 25-year-old patient presented with a constricted maxilla, a skeletal Class III malocclusion with a large mandible, Angle's Class III malocclusion, retroclined lower incisors, proclined upper incisors, crowding of maxillary and mandibular teeth, and bilateral posterior crossbite. The case report shows that an adult patient with Class III malocclusion (constricted maxilla and large mandible) can be treated with rapid maxillary expansion accompanied by bilateral maxillary osteotomies, followed by a reduction bilateral sagittal split osteotomy (BSSO). As the patient was 25 years old with a bilateral crossbite, a surgically assisted rapid maxillary expansion procedure was performed. As the diastema space was available at the end of expansion, it proved to be beneficial for the presurgical decompensation of Class III, thus creating a negative overjet, followed by which a BSSO setback was done.

Interdisiplinary collaboration of orthodontics and oral and maxillofacial surgery for the correction of severe class III skeletal pattern in an adult male with an hapsburg jaw - A case report on surgical orthodontics

This case report, aims to present a combined orthodontic and surgical approach in the treatment of an adult male patient with skeletal class III malocclusion with an Hapsburg jaw. The malocclusion was decompensated by pre-surgical orthodontic treatment and then normal jaw relationship was achieved by Bilateral Sagittal Split Osteotomy Setback followed by debonding after 4 months. The treatment lasted for over 14months, it improved facial esthetics and profile of the patient significantly and resulted in a normal occlusion, overjet, and overbite and a pleasant smile.

Management of Skeletal Class III Malocclusion due to Mandibular Prognathism Coexisting with Vertical Maxillary Excess

This case report describes combined orthodontic and orthognathic management of skeletal Class III malocclusion in a female patient presenting with prognathic mandible, increased maxillary height, severe hyperdivergence, gummy smile, and upper anterior proclination. Presurgical orthodontics involved extraction of maxillary first premolars and decompensating the proclined upper incisors. Orthognathic surgery involving differential maxillary impaction, mandibular bilateral sagittal split osteotomy setback, and sliding genioplasty. Postsurgical orthodontics was initiated one month after the surgery to finish the case in Class II molar relationship and Class I canine relationship with proper intercuspation. The outcome had acceptable results with good esthetics and occlusion.

Residents' journal review

Residents' journal review

Quality of Life Treatment Outcomes of Class III Skeletal Patients after Bimaxillary Osteotomies

Introduction: Bimaxillary osteotomies are commonly done to correct dentofacial deformities. Osteotomy at the LeFort I level and bilateral sagittal split osteotomy (BSSO) are commonly used in combination to treat patients with Class III skeletal dentofacial deformities. However, few studies are available which assess the treatment outcome measured in terms of quality of life (QoL) of Class III skeletal patients after bimaxillary osteotomies. This study aims to evaluate the long-term benefits of bimaxillary osteotomies, measured in terms of QoL outcomes of Class III skeletal patients at two (2) years post-surgery. Methods: This study was conducted at the National Dental Centre Singapore and selected patients were given 2 questionnaires each based on Oral Health Impact Profile (OHIP-14) and Orthognathic Quality of Life Questionnaire (OQLQ). The patients were told to report each question using a Likert-type scale and their perception for each question before and after surgery. Results: A total of 41 patients were recruited in this study, of which 23 were males and 18 were females. Their age ranged from 17 to 32 years old at the time of surgery and the median age was 20 years 2 months. All the patients in this study were Chinese. All the patients underwent LeFort I maxillary procedure in addition to BSSO setback surgery. The Wilcoxon Signed Rank test was used for evaluation of the statistics. There were significant changes to both OHIP-14 and OQLQ scores (p&lt;0.001) two-years post-operatively. All the OHIP-14 domains, functional limitation (p&lt;0.001), physical pain (p&lt;0.001), psychological discomfort (p&lt;0.001), physical disability (p=0.001), social disability (p&lt;0.001) and handicap (p&lt;0.001), were significantly decreased when compared to pre-surgical scores. The OQLQ domain scores, social aspects of deformity (p&lt;0.001), facial aesthetics (p&lt;0.001), oral function (p&lt;0.001), and awareness of facial deformity (p=0.013), were also significantly lower two-years post-operatively. Conclusion: Treatment outcomes measured in terms of QoL were significantly improved in Class III skeletal patients after bimaxillary osteotomies. The function, psychosocial and facial aesthetics improved significantly after surgery and these aspects continued well into two-years post-surgery. The inclusion of QoL as a routine treatment outcome measure in orthognathic surgery would be beneficial in clinical profiling of patients, decision making and evaluating the efficacy of the procedure. It could potentially be used to evaluate surgical complications, arising from orthognathic surgery, and its impact on QoL in patients. More studies would be required to establish its correlation in the future.

Residents' journal review

Residents' journal review

Differences in three-dimensional soft tissue changes after upper, lower, or both jaw orthognathic surgery in skeletal class III patients

The decision is not always straightforward as to which orthognathic procedure is best for a good aesthetic result; three-dimensional imaging has brought new insight into this topic. The aim of this prospective study was to verify objectively whether postoperative changes occur within those regions not directly affected by surgical movements of the underlying jaw bones. The study included 83 young adults with skeletal class III deformities. They were classified into three groups according to the type of surgery: bilateral sagittal split osteotomy set-back of the mandible (BSSO), Le Fort I advancement of the maxilla, or a combination of both. Pre- and postoperative optical scans were registered as regional best-fits on the areas of the foreheads and both orbits. The shell to shell differences were measured and the average distances between the observed regions were calculated. As expected, changes were greatest in the regions where the underlying bones had been moved, but regardless of the operation performed, changes were found over the whole face. Changes in the nose, cheek, and upper lip regions in the BSSO group and in the lower lip and chin region in the Le Fort I group confirmed the concept of the facial soft tissue mask acting as one unit.

Three-dimensional analysis of pharyngeal airway change of skeletal class III patients in cone beam computed tomography after bimaxillary surgery

Introduction: To evaluate the 3-dimensional changes in the pharyngeal airway of skeletal class III patients after bimaxillary surgery. Materials and Methods: The study sample consisted of 18 Korean patients that had undergone maxillary setback or posterosuperior movement and mandibular bilateral sagittal split osteotomy setback surgery due to skeletal class III malocclusion (8 males, 10 females; mean age of 28.7). Cone beam computed tomography was taken 1 month before and 6 months after orthognathic surgery. Preoperative and postoperative volumes of the nasopharyngeal, oropharyngeal, and laryngopharyngeal airways and minimum axial areas of the oropharyngeal and laryngopharyngeal spaces were measured. Moreover, the pharyngeal airway volume of the patient group that had received genioplasty advancement was compared with the other group that had not. Results: The nasopharyngeal and laryngopharyngeal spaces did not show significant differences before or after surgery. However, the oropharyngeal space volume and total volume of pharyngeal airway decreased significantly (P Conclusion: The results indicate that bimaxillary surgery decreased the volume and the minimum axial area of the oropharyngeal space. Advanced genioplasty did not seem to have a significant effect on the volumes of the oropharyngeal and laryngopharyngeal spaces.

The impact of Le Fort I advancement and bilateral sagittal split osteotomy setback on ventilation during sleep

The impact of orthognathic surgery for class III malocclusion on ventilation during sleep was examined using a comparison of pre- and post-surgical respiratory parameters. 21 patients with both maxillary hypoplasia and mandibular excess underwent Le Fort I osteotomy and advancement together with bilateral sagittal split osteotomy (BSSO) setback. Respiratory parameters, ECG and position of the body were monitored before surgery and postoperatively after the fixation removal (mean 8.5 months). Average Le Fort I advancement was 4.44 mm, BSSO setback was 4.96 mm. Generally, the orthognathic procedure worsened breathing function during sleep, as reflected in significant increase of index of flow limitations and decrease in oxygen saturation. The posterior airways space decreased to 75% of its original volume, the distance between mandibular plane and hyoid bone increased to 133%. The results indicate that bimaxillary surgery for class III malocclusion increased upper airway resistance. A young person would probably be able to balance such a decline in respiratory function using different adaptive mechanisms, but the potential impact of orthognathic surgery on the upper airways should be incorporated in a treatment plan.

Stability After Bilateral Sagittal Split Osteotomy Setback Surgery With Rigid Internal Fixation: A Systematic Review

The purpose of this systematic review was to evaluate relapse and its causes in bilateral sagittal split setback osteotomy with rigid internal fixation. Literature research was done in databases such as PubMed, Ovid, the Cochrane Library, and Google Scholar Beta. From the original 488 articles identified, 14 articles were finally included. Only 5 studies were prospective and 9 retrospective. The range of postoperative study records was from 6 weeks to 12.7 years. The horizontal short-term relapse was between 9.9% and 62.1% at point B and between 15.7% and 91.3% at pogonion. Long-term relapse was between 14.9% and 28.0% at point B and between 11.5% and 25.4% at pogonion. Neither large increase nor decrease of relapse was seen when short-term values were compared with long-term. Bilateral sagittal split osteotomy for mandibular setback in combination with orthodontics is an effective treatment of skeletal Class III and a stable procedure in the short- and long-term. The etiology of relapse is multifactorial: the proper seating of the condyles, the amount of setback, the soft tissue and muscles, remaining growth and remodeling, and gender were identified. Age did not show any correlations. To obtain reliable scientific evidence, further short- and long-term research of bilateral sagittal split osteotomy setback with rigid internal fixation should exclude additional surgery, ie, genioplasty or maxillary surgery, and include correlation statistics.

Stability of Soft Tissue Profile After Mandibular Setback in Sagittal Split Osteotomies: A Longitudinal and Long-Term Follow-Up Study

The aim of the study was to conduct a long-term prospective follow-up on the stability of soft tissues after bilateral sagittal split osteotomy (BSSO) with rigid internal fixation to set back the mandible. Seventeen consecutive patients (6 females, 11 males) were re-examined 12.7 years (T5) after surgery. The precedent follow-ups included: before surgery (T1), 5 days (T2) after surgery, 6.6 months (T3) after surgery, and 14.4 months after (T4) surgery. Lateral cephalograms were traced by hand, digitized, and evaluated with the Dentofacial Planner program (Dentofacial Software, Toronto, Canada). The x-axis for the system of coordinates ran through Sella (point 0) and the line NSL -7 degrees. The net effect of the soft tissue chin (soft tissue pogonion) was 79% of the setback at pogonion. At the lower lip (labrale inferior) it was 100% of the setback at lower incisor position. Point B' followed point B to 99%. Labrale inferior and menton' also showed a significant backward, as well as a downward, movement (T5 to T2). Gender correlated significantly (P = .004) with the anterior displacement of point B' and pogonion' (P = .012). The soft tissue relapse 12.7 years after BSSO setback surgery at point B' was 3% and 13% at pogonion'. Among the reasons for 3-dimensional long-term soft tissue changes of shape, the surgical technique, the normal process of human aging, the initial growth direction, and remodeling processes must be considered. Growth direction positively influenced the long-term outcome of setback surgery in female compared with male patients because further posterior movement of the mandibular soft tissue occurred.

Trigeminal nerve hypesthesia after sagittal split osteotomy in setback cases: correlation of postoperative computed tomography and long-term trigeminal somatosensory evoked potentials

Purpose: We sought to assess the relationship of the inferior alveolar nerve to the osteotomy site after bilateral sagittal split osteotomy (BSSO) and to correlate the nerve osteotomy relationship as the cause of long-term postoperative hypesthesia. Patients and Methods: The subjects consisted of 28 patients with mandibular prognathism who underwent BSSO setback surgery. The distance between the ostectomized surface of the mandibular ramus and mandibular canal was measured and scored on a computed tomograph (CT). The relationship between this distance and the presence and degree or absence of trigeminal nerve hypesthesia was objectively evaluated by latency delay of the trigeminal somatosensory evoked potential (TSEP) records. Results: Five of the 56 sides (8.9%) showed latency delays more than 1 year after the operations. Scored CT points between the canal and the split surface strongly correlated with TSEP latency recovery ( Y = 1.716 X + 41.2). Conclusions: This relationship between the canal and the osteotomy site is related to long-term hypesthesia in BSSO postoperatively.