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Aims: The purpose of this study is to compare the thickness and elasticity of the masseter muscle before and after orthognathic surgery in patients with class III skeletal deformity and to investigate the relationship between the sonographic changes in the masseter muscle and the amount of mandibular setback., Subjects and Methods: The study group consisted of 14 patients with skeletal class III malocclusions who had orthognathic surgery. The control group consisted of 14 patients who had dental and skeletal class I occlusion. Muscle thickness measurements were performed with B-mode and high-frequency linear scanning probe of the ultrasound device. Elastography feature and muscle hardness ratio were obtained by applying compression and decompression on muscles at rest and during maximum contraction in the transverse plane. Patients were categorized into two groups according to the mandibular setback as <5 mm and ≥5 mm., Results: The masseter muscle thickness after surgery was found statistically increased bilaterally in both at rest and during contraction for the study group (P < 0.05). No difference was found between preoperative orthognathic measurements and postoperative measurements for elasticity index ratio measurements (P > 0.05)., Conclusion: We believe that in the present study important findings have been emphasized for further research aiming to investigate the possible relationship between masticatory alterations and surgical outcomes after orthognathic surgery., Competing Interests: None

The possible negative outcomes of mandibular setback surgery (MSS) on the upper airway (UA) have become an important issue in recent years. The purpose of the present study was to compare the different amounts of MSS and to confirm the accepted maximum amount of mandibular setback by using Computational Fluid Dynamics (CFD) method. An anatomically similar UA model was constructed from magnetic resonance images of a systemically healthy individual. Two out of six models were kept as control models and the remaining four models were created to represent MSS scenarios with different amounts to correct Class III skeletal abnormality. The airflow was assumed laminar, incompressible, and the surrounding soft tissue was assumed to be linear elastic. The sixth model that was representative of 15 mm of MSS showed statistically significant differences from the other models (p < 0.05). No significant differences were observed among other models in terms of all the parameters (p > 0.05). CFD has been recently used in researches by modeling the UA flow; however, to the best of our knowledge, none of the studies have proved the maximum limits of MSS amounts with this technique. Graphical abstract ᅟ.

Objectives: This study examined the changes in temporomandibular joint dysfunction (TMD) symptoms and investigated the variations in the disc position, disc and condylar morphology following sagittal split ramus osteotomy (SSRO) with rigid fixation in patients with mandibular prognathism. Furthermore, the authors examined the correlation between mandibular setback and TMD symptoms., Methods: The study included 24 Japanese patients with jaw deformities who were treated using bilateral SSRO and Le Fort I osteotomy. The clinical and magnetic resonance imaging findings in the temporomandibular joint were evaluated preoperatively and at three and six months postoperatively., Results: The preoperative TMD symptoms were significantly associated with the prevalence of TMD symptoms at six months postoperatively. Anterior disc displacement improved in four joints with slight displacement and with no morphological change. There were no postoperative changes in condylar morphology. There was no significant correlation between mandibular setback and the postoperative TMD symptoms., Conclusion: Postoperative TMD symptoms may be influenced mainly by preoperative TMD symptoms rather than mandibular setback using SSRO with rigid fixation. Therefore, patients with TMD symptoms require physical examination and MRI for appropriate diagnosis preoperatively.

Accurate prediction of hard and soft tissue changes is essential in orthognathic surgery. The aim of the present study was to systematically investigate the relation between soft and hard tissue relocation after mandibular setback surgery. A systematic search was performed, correlation coefficients and ratios were retrieved from the eligible studies, and the risk of bias was assessed. The random effects method was used to combine data. The five eligible studies showed that sagittal changes in pogonion, point B, and incision inferius incisalis are highly correlated with respective soft tissue movements and exhibit ratios ranging from 0.915 to 1.051. Only two studies were classified as having a moderate risk of bias. Although the characteristics of the included data limit the formation of definite conclusions, the soft to hard tissue movement ratios produced constitute initial clinically relevant guidance. Further long-term standardized and well-conducted trials are needed., (Copyright © 2016 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

The aims of this study were to analyze possible contributing factors to intraoperative clockwise rotation (CWR) of the proximal segment (PS), which is known to be a primary factor for relapse after mandibular setback with sagittal split ramus osteotomy (SSRO) and to evaluate the correlation between the CWR of the PS and relapse tendency. The sample was comprised of 47 patients who underwent SSRO for mandibular setback. Lateral cephalograms were analyzed. The vertical difference between the inferior borders of the PS and the distal segment at the vertical osteotomy line for SSRO after setback of the distal segment (vertical bony step, VBS) was the most predictable factor for CWR of the PS (p < 0.001), and it correlated significantly with the gonial angle, the surgical change in SNB, and the downward movement of the maxilla (p < 0.05). Patients with large CWR of the PS showed a greater tendency in horizontal relapse than patients with small CWR of the PS (p < 0.05). Such relapse patterns could be prevented with adequate surgical planning designed to reduce the VBS, such as maxillary posterior impaction or the intentional guidance of the PS to maintain the original position of the PS without CWR., (Copyright © 2013 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

Aesthetic outcome has gained in importance in the treatment of patients with orthognathic problems. Historically, Class III malocclusions have historically been treated by isolated mandibular setback and maxillary advancement, whereas bimaxillary procedures have recently become the more common option. Functional outcome and stability have been discussed previously. The aim of this observational study was to evaluate the effect of mandibular setback (BSSO) on the cervical region. We studied 38 Class III patients (20 women and 18 men, mean (SD) age 25 (0.8) years) who we identified from our clinical records and who were treated between 1 January 2002 and 30 December 2012 with mandibular setback procedures and followed up for 6 months. To study the effect of the amount of mandibular setback on the aesthetic outcome we have distinguished between patients with less than 5mm setback and those with 5mm or more. In patients whose mandibular setback was less than 5mm there was no significant change in cervical length. However, it decreased significantly in patients in whom the movement was 5mm or more. Postoperatively the lip-chin-throat angle (p=0.02), the length of the lower lip (p=0.002), and the length of the upper lip (p=0.003) from the aesthetic line also differed significantly between the 2 groups. Our observations strongly suggest that all these relations should be considered when treatment is being planned to avoid an unpleasant aesthetic impact on the chin region., (Copyright © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Objectives: This study examined the changes in temporomandibular joint dysfunction (TMD) symptoms and investigated the variations in the disc position, disc and condylar morphology following sagittal split ramus osteotomy (SSRO) with rigid fixation in patients with mandibular prognathism. Furthermore, the authors examined the correlation between mandibular setback and TMD symptoms.Methods: The study included 24 Japanese patients with jaw deformities who were treated using bilateral SSRO and Le Fort I osteotomy. The clinical and magnetic resonance imaging findings in the temporomandibular joint were evaluated preoperatively and at three and six months postoperatively.Results: The preoperative TMD symptoms were significantly associated with the prevalence of TMD symptoms at six months postoperatively. Anterior disc displacement improved in four joints with slight displacement and with no morphological change. There were no postoperative changes in condylar morphology. There was no significant correlation between mandibular setback and the postoperative TMD symptoms.Conclusion: Postoperative TMD symptoms may be influenced mainly by preoperative TMD symptoms rather than mandibular setback using SSRO with rigid fixation. Therefore, patients with TMD symptoms require physical examination and MRI for appropriate diagnosis preoperatively. [ABSTRACT FROM AUTHOR]

Background Mandibular setback used to be the traditional treatment of choice for correcting mandibular prognathism. Nowadays, bimaxillary surgery is preferred. Several authors have asserted that mandibular setback causes a relative narrowing of the upper airway (UA) that could trigger obstructive sleep apnoea (OSA); however, its potential role in OSA development is still much debated. Another controversial subject is whether changes in airway space caused by the procedure are permanent. Objectives To ascertain the consequences for UA size and shape of mandibular setback surgery in comparison with bimaxillary surgery (maxillary advancement with Le Fort I and mandibular setback), and to analyse the changes in oximetric indices and their relationship with OSA. Search methods A systematic review was made of the bibliography in 4 databases: Medline, Scopus, Embase and Cochrane. Selection criteria Systematic reviews, meta-analyses, clinical trials and cohort and case–control studies of adults published in the past 15 years were included. Data collection and analysis The initial search yielded 668 articles, of which 498 were eliminated because of duplication and 123 on the basis of their titles and abstracts or summaries. The remaining 47 papers were read in their entirety, and 14 were included in the final selection. Results According to our observations, the nasopharyngeal space does not undergo significant changes after either of the two surgical procedures. In the oropharynx and hypopharynx, none of the measurements changed significantly with maxillary advancement; however, persistent and significant decreases in the area, horizontal linear dimensions, and volume of these spaces are encountered after mandibular setback alone. No long-term changes in oximetric indices were found. Conclusions Morphological changes are more pronounced following exclusively mandibular surgery. A decrease in the UA does take place but appears not to affect the patient's sleep quality. This study found no evidence to confirm that bimaxillary or mandibular orthognathic surgery predisposes to obstructive sleep apnoea development. [ABSTRACT FROM AUTHOR]

Objective: To determine the changes in articular disk position and the temporomandibular joint (TMJ) structure in patients who had an asymmetric setback of the mandible performed by a bilateral sagittal split ramus osteotomy with manual positioning of the condyle. Materials and Methods: Twenty-two patients with skeletal Class III malocclusion being treated at Nara Medical University Hospital were evaluated using clinical examination and pre- and post-operative magnetic resonance images of their TMJs. Results: Changes in articular disk position after asymmetric setback surgery were not statistically significant, although a tendency of anterior displacement in the fossa was noted. The anterior and posterior joint spaces did not show significant changes, whereas the condyle head of the deviated or contralateral side tended to be positioned downward. Conclusion: The asymmetric setback of the mandible with intraoperative manual positioning of the condyle does not significantly change the disk position in the fossa. [ABSTRACT FROM AUTHOR]

Short- and long-term skeletal changes after mandibular setback were analyzed using bilateral sagittal split ramus osteotomy. Twelve patients who had undergone mandibular setback surgery between 1986 and 1990 were available for long-term cephalography on average 12 years after primary surgery. The mean amount of surgical setback had been 6.4?mm. After the first postoperative year, there was skeletal relapse of 1?mm at the B-point and pogonion (Pg), amounting to 14% of the initial skeletal setback. In contrast to condylar displacement and proximal segment rotation, osteotomy slippage was associated with positional changes at the B-point and Pg. From 1 to 12 years postoperatively, the B-point and Pg remained stable. Mandibular ramus and corpus length decreased 2.1?mm and 1.3?mm, respectively, indicating remodeling at the osteotomy sites and probably condylar resorption. [ABSTRACT FROM AUTHOR]

Summary: Introduction: The purpose of this study was to determine long-term changes in hyoid bone position and pharyngeal airway size after mandibular setback osteotomies. Material and methods: Serial cephalograms of 12 patients who underwent mandibular setback surgery were evaluated preoperatively, at 1 week, 6 months, and 14 months postoperatively, and finally after an average of 12 years. Results: A mean setback of 5.6mm was associated with a posterior and inferior movement of the hyoid bone. At long-term follow-up, the hyoid bone adapted horizontally to a position about 1.6mm more posterior than its preoperative location. Immediately after surgery, the length of suprahyoid muscles correlated significantly with skeletal movements: suprahyoid muscles shortened by 4mm but started lengthening after 1 year. Thereafter, it tended to correlate with the change of hyoid bone position rather than with skeletal relapse. Following the initial decrease after surgery, the size of the lower pharyngeal airway remained almost unchanged. The upper and middle pharyngeal airway sizes continued to decrease over the postoperative period of 12 years, and ultimately were smaller than their preoperative sizes by about 1.5 and 3mm, respectively. [Copyright &y& Elsevier]