Fracture patterns of two sagittal split ramus osteotomy techniques: a cadaveric study.

Context: Using a reliable fixation method after ramus sagittal split osteotomy in order to reduce the chances of treatment relapse and condyle changes is still one of the most noteworthy issues discussed among maxillofacial surgeons. In this study, the results of the up-to-date papers were collected, which identify the eects of the fixation method on the post-operative results, to give the reader a comprehensive view of the new concepts. Evidence Acquisition: The most frequent mandibular surgeries, setbacks, and advancements via the bilateral sagittal split os- teotomy technique were used for a literature search due to the abundance of related articles. Consequently, the following keywords were applied: sagittal split ramus osteotomy, orthognathic surgery, rigid fixation, non-rigid fixation, postoperative relapse, and postoperative stability. Results: The articles were classified according to the surgery procedure: mandibular advancement surgery or mandibular setback surgery. The relapse pattern can be divided into two categories: an early relapse, which is strongly related to the surgery proce- dure, and a late relapse, which can be attributed to the physiologic changes, such as a growth map. The contributing factors can be considered to be the following: a change in ramus in inclination, the mandibular plane, and the fixation type. Conclusions: Using rigid fixation techniques after bilateral sagittal split ramus osteotomy will optimize the stability, but this sta- bility is not influenced by the method of this rigid fixation; although the most commonly suggested technique, bicortical screws, is in the inverted-L position

The purpose of this study was to investigate the changes in tongue-palatal contact patterns using electropalatography (EPG) before and after sagittal split ramus osteotomy (SSRO) in patients with mandibular prognathism. Nine clients who underwent SSRO for mandibular setback and seven control subjects were participated in this study. Tongue-palatal contact patterns for /t/, /s/ and /k/ production were investigated using EPG before surgery and 3 months after surgery. The mean value of whole total of palate contact (WT) in the maximum contact frame was examined before and after SSRO. The correlation quantity between the change of center of gravity (COG) value and the amount of mandibular setback was also evaluated. The mean value of WT for /t/ and /s/ significantly increased after SSRO, and the EPG pattern became normal. However, a remarkable change in WT for /k/ was not observed, and the mean value was significantly larger in the SSRO group before and after surgery than in the control group. A negative correlation between COG variation and the amount of mandibular setback for /t/ and positive correlation for /s/ was observed. This study demonstrated that tongue-palatal contact patterns for /t/ and /s/ articulation improved clearly after SSRO. There was a significant correlation between COG variation and the amount of mandibular setback. However, no significant change was detected through perceptual assessment before and after SSRO. Further investigation is needed to determine whether these results will change over time.

The sagittal split ramus osteotomy is a well-established procedure, and many authors have attempted various modifications of the surgical technique. Nowadays, it is widely acknowledged that people in Korea, Japan, and China prefer an oval face, the lower part of which is slender. Therefore, among facial contouring procedures, the mandible reduction procedure is the most popular procedure in these countries. It is quite difficult for patients to undergo two different procedures on almost the same region separately. For patients who underwent sagittal split ramus osteotomy on their mandible for various reasons, the authors performed mandible reduction at the same time if necessary. In the event that two procedures are performed simultaneously, the risk would be higher regarding postoperative stability, but there was no significant problem in achieving stable occlusion after surgery through a rigid fixation technique and 2 weeks of rigid intermaxillary fixation. The authors attained satisfactory aesthetic results and good postoperative stability by performing sagittal split ramus osteotomy and mandible reduction at the same time. This procedure is thought to be useful for patients who are to undergo sagittal split ramus osteotomy for various reasons and want to have a slender lower face.

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

Effect of bone quality and position of the inferior alveolar nerve canal in continuous, long-term, neurosensory disturbance after sagittal split ramus osteotomy

BackgroundFibula free flap mandible reconstruction is the standard procedure after wide resection of the mandible. Establishment and maintenance of normal occlusion are important in mandible reconstruction both intraoperatively and after surgery. However, scar formation on the surgical site can cause severe fibrosis and atrophy of soft tissue in the head and neck region.Case presentationHere, we report a case of severe soft tissue atrophy that appeared along with scar formation after mandibular reconstruction through the fibular free flap procedure. This led to normal occlusion collapse after it was established, and the midline of the mandible became severely deviated to the affected side that was replaced with the fibula free flap, leading to facial asymmetry. We corrected the malocclusion with a secondary operation: a sagittal split ramus osteotomy on the unaffected side and a sliding osteotomy on the previous fibula graft. After a healing time of 3 months, implants were placed on the fibula graft for additional occlusal stability.ConclusionWe report satisfactory results from the correction of malocclusion after fibula reconstruction using sliding fibula osteotomy and sagittal split ramus osteotomy. The midline of the mandible returned to its original position and the degree of facial asymmetry was reduced. The implants reduced difficulties that the patient experienced with masticatory function.

Computed tomography assessment of mandibular morphologic changes and the inferior mandibular border defect after sagittal split ramus osteotomy

Three-dimensional finite element assessment of grid-type plate in 2 different designs of sagittal split osteotomy of the mandibular ramus.

Neurosensory disturbance after sagittal split and intraoral vertical ramus osteotomy: as reported in questionnaires and patients’ records

The existence of cancellous bone between buccal and lingual cortical plates provides guidance for the desired split plane through the osteotomy lines and interruptions increase the risk of unfavorable fractures during sagittal split ramus osteotomy (SSRO). The aim of this study is to present a rare case of SSRO in the absence of cancellous bone concerning the osteotomy sites, a conservative approach using piezosurgery and bone separators to avoid complications.

Retrospective study of changes in the sensitivity of the oral mucosa: sagittal split ramus osteotomy (SSRO) versus intraoral vertical ramus osteotomy (IVRO)

To determine whether the condylar rotation is affected by asymmetric setback in patients undergoing sagittal split ramus osteotomy. Thirty patients who underwent bilateral sagittal split ramus osteotomy setback surgery were divided into the two groups, symmetric setback and asymmetric setback, according to the right/left difference of setback amount (<2.0, ≥2.0 mm). Condylar long axis changes were evaluated using the three-dimensional superimposition of before and immediately after surgery cone-beam computed tomography volume images. Evaluations were performed separately in lesser setback and greater setback side in patients undergoing asymmetric setback, whereas both side condyles were evaluated together in patients undergoing symmetric setback. Condylar axis changes on axial view were correlated with setback amount or right/left setback difference using Pearson correlation analysis. In general, the condylar axis change occurred in a pattern of inward rotation. The condyles in patients undergoing symmetric setback showed 3.4° rotation in average. In case of asymmetric setback, the lesser setback side showed larger value (4.3°) than the greater setback side (2.3°) with a statistical significance. In the correlation analysis, setback amount showed no significant correlation with the condylar axis changes in both groups. However, correlation with right/left setback difference showed a positive correlation in lesser setback side of patients undergoing asymmetric setback. The findings of this study indicate that large amount of setback alone does not contribute to the change in condylar long axis, but asymmetric setback might cause a change in condylar long axis, particularly on the lesser setback side.

An In Vitro Evaluation of Rigid Internal Fixation Techniques for Sagittal Split Ramus Osteotomies: Setback Surgery

Purpose: The purpose of present study was to review the literature regarding the postoperative skeletal stability in the treatment of mandibular prognathism after isolated sagittal split ramus osteotomy (SSRO) or intraoral vertical ramus osteotomy (IVRO). Materials and Methods: The articles were selected from 1980 to 2020 in the English published databases (PubMed, Web of Science and Cochrane Library). The articles meeting the searching strategy were evaluated based on the eligibility criteria, especially at least 30 patients. Results: Based on the eligibility criteria, 9 articles (5 in SSRO and 4 in IVRO) were examined. The amounts of mandibular setback (B point, Pog, and Me) were ranged from 5.53–9.07 mm in SSRO and 6.7–12.4 mm in IVRO, respectively. In 1-year follow-up, SSRO showed the relapse (anterior displacement: 0.2 to 2.26 mm) By contrast, IVRO revealed the posterior drift (posterior displacement: 0.1 to 1.2 mm). In 2-year follow-up, both of SSRO and IVRO presented the relapse with a range from 0.9 to 1.63 mm and 1 to 1.3 mm respectively. Conclusion: In 1-year follow-up, SSRO presented the relapse (anterior displacement) and IVRO posterior drift (posterior displacement). In 2-year follow-up, both of SSRO and IVRO showed the similar relapse distances.

Sagittal split ramus osteotomy (SSRO) with large mandibular advancements is a common surgical procedure and could be indicated for patients with sleep apnoea. As a large variety of fixation methods is used for the stabilisation of SSRO, a biomechanical test model was used to analyse which fixation technique was most stable. For this in vitro study, 80 polyurethane hemimandibles with a prefabricated SSRO were used as substrates. Loads in Newtons were recorded at displacements of the mandibular incisive edge at 1mm, 3mm and 5mm. The samples were divided into two groups: mandibular advancements of 10mm and 15mm. In both groups, four fixation techniques were used: (A) one four-hole miniplate; (B) two four-hole miniplates; (C) one four-hole miniplate plus one bicortical screw; and (D) three bicortical screws in an inverted-L arrangement. In group 1, three bicortical screws resulted in the best stability, and in group 2, two miniplates resulted in the best stability. The use of two miniplates did not show significant differences between both groups. Other fixation methods showed more stability with 10mm advancements. This study therefore suggests that in SSRO with advancements exceeding 10mm, the use of two miniplates is the optimal means of providing rigid fixation.