Unilateral Sagittal Split Ramus Osteotomy Research Articles

Positional changes of the mandibular condyle in unilateral sagittal split ramus osteotomy combined with intraoral vertical ramus osteotomy for asymmetric class III malocclusion.

ObjectivesIn the present study, the effects of sagittal split ramus osteotomy (SSRO) combined with intraoral vertical ramus osteotomy (IVRO) for the treatment of asymmetric mandible in class Ⅲ malocclusion patients were assessed and the postoperative stability of the mandibular condyle and the symptoms of temporomandibular joint disorder (TMD) evaluated.Materials and MethodsA total of 82 patients who underwent orthognathic surgery for the treatment of facial asymmetry or mandibular asymmetry at the Department of Oral and Maxillofacial Surgery, Dong-A University Hospital, from 2016 to 2021 were selected. The patients that underwent SSRO with IVRO were assigned to Group I (n=8) and patients that received bilateral SSRO (BSSRO) to Group II (n=10, simple random sampling). Preoperative and postoperative three-dimensional computed tomography (CT) axial images obtained for each group were superimposed. The condylar position changes and degree of rotation on the superimposed images were measured, and the changes in condyle based on the amount of chin movement for each surgical method were statistically analyzed.ResultsGroup I showed a greater amount of postoperative chin movement. For the amount of mediolateral condylar displacement on the deviated side, Groups I and II showed an average lateral displacement of 0.07 mm and 1.62 mm, respectively, and statistically significantly correlated with the amount of chin movement (P=0.004). Most of the TMD symptoms in Group I patients who underwent SSRO with IVRO showed improvement.ConclusionWhen a large amount of mandibular rotation is required to match the menton to the midline of the face, IVRO on the deviated side is considered a technique to prevent condylar torque. In the present study, worsening of TMD symptoms did not occur after orthognathic surgery in any of the 18 patients.

Biomechanical effect of asymmetric mandibular prognathism treated with BSSRO and USSRO on temporomandibular joints: a three-dimensional finite element analysis.

Asymmetric mandibular prognathism is a clinically common skeletal dentomaxillofacial deformity. Unilateral sagittal split ramus osteotomy (USSRO) is an effective alternative procedure to bilateral sagittal split ramus osteotomy (BSSRO) for some patients. However, the biomechanical effect of temporomandibular joint (TMJ) of USSRO has not been fully studied. This study aims to evaluate the stress distribution changes in the TMJ of asymmetric mandibular prognathism treated with BSSRO/USSRO, to validate the clinical feasibility of USSRO. Nineteen patients with mandibular prognathism patients who were treated with BSSRO (n=12) and USSRO (n=7) had preoperative and postoperative computed tomographic scanning. Preoperative and postoperative 3-dimensional finite element analysis (FEA) of functional TMJ movements were made on one BSSRO patient and one USSRO patient. In all patients, the ANB angle and mandibular deviation were significantly improved postoperatively. There was no significant difference in the postoperative ANB angle and mandibular deviation between the BSSRO group and the USSRO group. In two preoperative FEA models, the maximum stresses of non-deviation side TMJ structures were greater than the deviation side during functional movements. The unbalanced stress distribution was corrected postoperatively in both BSSRO/USSRO FE models. Both BSSRO/USSRO can improve the ANB angle and mandibular deviation. The bilateral TMJ structure in patients with asymmetric mandibular prognathism had unbalanced stress, which could be significantly improved with the USSRO as effectively as BSSRO.

Comparison of postoperative condylar changes after unilateral sagittal split ramus osteotomy and bilateral sagittal split ramus osteotomy using 3-dimensional analysis

This study aimed to evaluate postoperative changes in the condyle after unilateral sagittal split ramus osteotomy (USSRO) and to compare them with changes occurring after bilateral sagittal split ramus osteotomy (BSSRO). For 50 condyles from 25 patients, positional and volumetric changes of condyle were analyzed by using computed tomography images taken before, immediately after, and 6 months after surgery and compared between the USRRO and BSSRO groups. The condyle showed lateral and inferior displacement immediately after surgery and medial and superior movement at 6 months after surgery in the USSRO and BSSRO groups. No statistically significant difference was found between the 2 groups in the time-course positional change and rotation of the condyle. In the comparison of bodily shift and rotation between operated and nonoperated sides in USSRO group, there were no significant differences between the 2 sides, except for the perioperative rotation pattern on the coronal plane. At 6 months after surgery, the changed volume relative to preoperative condylar volume was only 5.2% in the USSRO group and 2.7% in the BSSRO group. The findings from this study suggest that USSRO can be used effectively in appropriately selected patients; however, temporomandibular joint (TMJ) problems may arise when condylar displacement is excessive enough to exceed physiologic tolerances.

Unilateral sagittal split ramus osteotomy for facial asymmetry by IIG

Treating cases of facial asymmetry is always a challenge for oral and maxillofacial surgeons especially when the face has minor deformities and patients expectations are very high. Various non surgical and surgical techniques including orthognathic and orthomorphic surgeries with graftings have kept their milestones for treating such cases. This report presents a similar case of achieving fullness on unilateral side of face to accomplish symmetry which was treated using an interpoistional iliac graft in unilateral saggital split osteotomy to correct the disharmony of face.

Mandibular unilateral sagittal split osteotomy-case report

Background: Bilateral sagittal split ramus osteotomy is considered a standard technique in mandibular orthognathic surgeries to reduce unexpected bilateral stress in the temporomandibular joints. Unilateral sagittal split ramus osteotomy (USSO) was recently introduced to correct facial asymmetry caused by asymmetric mandibular prognathism and has shown favorable outcomes.

Usefulness of Early Plate Removal in Patients With Occlusal Discrepancies After Sagittal Split Ramus Osteotomy.

The aim of this study was to evaluate the effects of early removal of fixed plates in patients with occlusal discrepancies after sagittal split ramus osteotomy (SSRO) with a focus on the positional relationship of the temporomandibular joint (TMJ). Sagittal split ramus osteotomy with/without Le Fort I osteotomy was performed on 98 patients with mandibular prognathism. Of these 98 patients, 15 with occlusal discrepancies and/or TMJ symptoms underwent early plate removal after SSRO. Finally, 12 consecutive patients were evaluated in this study: 7 underwent bilateral SSRO, 1 underwent unilateral SSRO, and 4 underwent bilateral SSRO with maxillary advancement. The axiolateral TMJ Schuller method was used to evaluate the TMJ position. The authors measured 3 spaces (anterior, superior, and posterior joint spaces) between the condyle and glenoid fossa in the sagittal plane. The anterior and superior joint spaces were significantly larger immediately after the operation than before the operation. After early plate removal, these spaces significantly decreased in size. The posterior joint space increased, but with no significant difference. Three months after SSRO, the size of each of the 3 spaces was closely related to its preoperative size. In conclusion, these results suggest that early removal of fixed plates is 1 treatment option for postoperative occlusal discrepancies after SSRO.

Orthodontic treatment in conjunction with distraction osteogenesis and orthognathic surgery for severe facial asymmetry

Abstract The present case report describes the combination of orthodontic treatment and two-stage surgery used to treat a 16-year-old female with a severe maxillary occlusal cant and a mandibular deviation. The patient was diagnosed with right temporomandibular joint ankylosis six months after suffering a facial injury at five years of age. A unilateral condylectomy was performed 12 months later. A hybrid functional appliance was used between nine and 16 years of age to prevent deterioration of the maxillary occlusal cant. At 16 years and six months, it was determined that the patient required a combination of surgical and orthodontic treatment, the pre-surgical orthodontic phase of which was completed at 19 years. The surgery was performed in two stages, which involved a Le-Fort 1 procedure to intrude the maxilla in the left molar region and to extrude in the right molar region. Distraction osteogenesis was performed to achieve a lengthening of the right mandibular ramus. The second operation was a unilateral sagittal split ramus osteotomy to achieve a forward and upward rotation of the left hemimandible. As a result, the patient’s facial asymmetry and occlusion significantly improved. The improvements were well maintained and the patient remained stable after one year of retention.

Unilateral sagittal split ramus osteotomy: an alternative for some cases of asymmetric mandibular prognathism

The objective of this study was to propose a treatment protocol for patients with lateral prognathism based on the unilateral sagittal split ramus osteotomy (USSRO). This was a prospective study involving 31 patients with lateral prognathism, who required a bilateral sagittal split ramus osteotomy (BSSRO). Two groups were formed using the proposed protocol, with specific inclusion criteria for each group: BSSRO (n=17) and USSRO (n=14). Occlusal parameters (dental midline deviation, overbite, and overjet) were measured preoperatively (T0), at model surgery (T1), 1 month postoperative (T2), and 1year after surgery (T3) and compared. P-values of <0.05 were considered significant. No significant difference was found between the USSRO and BSSRO groups for all occlusal parameters (T0, T1, T2, and T3). In both groups, there was a significant difference between T0 and T1 and no significant difference between T1 and T2 or T1 and T3 in all of the occlusal parameters; the exception was overbite between T1 and T2 in the BSSRO group, which showed a significant difference. No patient in either group showed signs or symptoms of temporomandibular joint dysfunction at T0 or T3. USSRO was found to be a stable alternative in patients with asymmetric mandibular prognathism. At the same time, it reduced the operating time and morbidity when compared to BSSRO.

Unilateral sagittal split mandibular ramus osteotomy: indications and geometry

Small mandibular asymmetries may be corrected by unilateral sagittal split ramus osteotomy (USSO). This study had two objectives: first to define the geometric changes in the mandibular condyle and the lower incisor teeth that result from the rotation of the major segment (n=26), and secondly to examine in a clinical study the temporomandibular joints (TMJ) of 23 patients after correction of mandibular asymmetry by USSO to find out if there were any long-term adverse effects. Small mandibular asymmetries (<5mm) can be corrected by USSO. Secondary anteroposterior changes as a result of setback or advancement on the operated side should be taken into account during the planning of treatment. The small rotational changes of the condyle did not adversely affect the TMJ.

Surgical Treatment of Hemimandibular Hyperplasia Leading to Unilateral Overdevelopment of the Face

Introduction:: Hemimandibular hyperplasia is a facial deformity which may develop in any age and includes a unilateral enlarged mandibular condylar head, deviation of mandible and chins, elongated condylar neck or ramus, and an occlusal cant with open bite. Different surgical treatments are proposed in the literature from simple low or high condylectomy to more complex procedures combining osteotomies in different sites of the mandible. Surgical procedure is defined by the clinical evaluation and scintigraphic diagnosis of activity or inactivity in the center of condylar growth. Case Presentation:: This case report describes a 30-year-old female patient with left hemimandibular hyperplasia with activity of condylar growth, that was successfully treated with low condylectomy, asymmetric lefort I osteotomy and inferior border ostectomy on the affected side, and associated with a unilateral sagittal split ramus osteotomy on the contra-lateral side. Discussion:: The innovation on nerve dissection by removing the overlying buccal bone and performing inferior ostectomy under direct visualization of the nerve, proved to be a safe technique with a low risk of nerve damage.

Changes in the lip-line in asymmetrical cases treated with isolated mandibular surgery

The aim of this study was to investigate changes in the lip-line in asymmetrical cases treated with mandibular osteotomy alone. Retrospective study. Hiroshima University Institute of Biomedical & Health Sciences, Hiroshima, Japan The subjects in this study consisted of 30 patients with an altered lip-line inclination who underwent isolated mandibular osteotomy (bilateral or unilateral sagittal split ramus osteotomy or intraoral vertical ramus osteotomy) as part of their surgical correction. Frontal cephalograms and facial photographs, taken at the first examination and after treatment, were used to measure changes in the inclination of the lip-line and cant of the occlusal plane, as well as the lateral deviations of hard and soft tissue Menton. Inclination of the lip-line after active treatment was significantly improved compared with that before treatment. Menton on the hard and soft tissues after active treatment also experienced a significant improvement compared with its position at first examination. One-jaw mandibular osteotomy is able to improve the inclination of the lip-line even in the presence of an occlusal cant. The inclination of the lip-line is corrected in association with sufficient lateral movements of Menton on the mandible.

Reinforced bioresorbable implants for craniomaxillofacial osteosynthesis in pigs

Our aim was to design a new bioresorbable fixation device for craniomaxillofacial surgery based on reinforcement of fibres between 2 different polymers. The final device, the 2.8mm polyglycolide fibre-reinforced-poly-l-lactide screw (PGA FR-PLLA; PLLA/PGA: 70%:30%), was evaluated for its mechanical properties and compared with a commercial resorbable device that was not reinforced with fibre. To model clinical conditions, a unilateral sagittal split ramus osteotomy fixation model in pigs was then used to compare the clinical effectiveness of the resorbable screw with that of a titanium screw in vivo, followed by 3-dimensional reconstructive imaging and histological analysis. Finally, an ex vivo biomechanical test was completed to investigate the immediate fixation stability of the newly designed screws. The PGA FR-PLLA screw resulted in clinical healing that was comparable to that of the titanium screw and was mechanically superior to the commercial device, indicating that the newly-developed screws have a potential clinical application.

Distraction osteogenesis of the mandibular ramus in hemifacial microsomia

To study the application of distraction osteogenesis (DO) of the mandibular ramus in hemifacial microsomia. From 1999 to 2006, 15 patients with hemifacial microsomia were treated with DO of the ramus, including 12 cases of children and juveniles, 3 cases of grown-ups. Maxillary Le Fort I osteotomy, unilateral sagittal split ramus osteotomy, genioplasty and free scapular flaps were selected to perform on the first or secondary stage of treatment. Successful distraction was achieved in all patients with an average distraction distance of 21.25 mm. The distractor was removed after consolidation proved by clinical examination and X-ray. Facial appearance and and occlusal relationship were improved greatly. The occlusal plane was almost normal. There was no infection, malunion or permanent injury of inferior alveolar nerve. DO of the ramus is very effective for the correction of severe hemifacial microsomia. It has much better therapeutic effect than traditional orthognathic procedures.

Surgical Correction of Mandibular Asymmetry by Unilateral Sagittal Split Ramus Osteotomy Combined with Contra-Lateral Vertical Ramus Osteotomy

In the surgical correction of mandibular deformities by mandibular retrusion, there is little difference in usefullness between sagittal split and vertical ramus osteotomies.However, vertical ramus osteotomy causes less rotational displcement of the proximal segment in asymmetric retrusion. Sagittal split ramus osteotomy is easier in the intraoral rigid internal fixation.Then unilateral sagittal split ramus osteotomy combined with contralateral intraoral vertical ramus osteotomy was done with these advantages for the surgical correction of mandibular asymmetry.The intermaxillary fixation between 1 and 2 weeks was sufficient in these osteotomies and good postoperative stability was naturally observed.The many preoperative symptoms and signs of temporomandibular joints were also improved after the correction of mandibular asymmetry by this technique. Never new symptoms of temporomandibular joints were observed following the treatment by this technique.