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Porcine mandibular defect models are commonly used for the preclinical evaluation of reconstruction techniques. Existing studies vary in technique, complexity, and postoperative outcomes. The procedures are complex and often described without sufficient detail. We describe in detail a simple and reproducible method for creating a critical-size mandibular defect in a porcine model. Seven hemimandibular critical size defects were created in five male Yorkshire-Landrace pigs, three with unilateral defects and two with bilateral defects. A transverse incision was made over the mandibular body. Periosteum was incised and elevated to expose the mandibular body and a critical-size defect of 30 × 20 mm created using an oscillating saw. The implant was inserted and fixed with a titanium reconstruction plate and bicortical locking screws, and the wound closed in layers with resorbable sutures. Intraoral contamination was avoided. Dentition was retained and the mental nerve and its branches preserved. The marginal mandibular nerve was not encountered during dissection. All pigs retained normal masticatory function, and there were no cases of infection, wound breakdown, haematoma, salivary leak, or implant-related complications. The procedure can be performed bilaterally on both hemimandibles without affecting load-bearing function. All pigs survived until the end point of three months. Postoperative computed tomographic scans and histology showed new bone formation, and a three-point bend test showed the restoration of biomechanical strength. Straight-segment mandibulectomy is a simple and reproducible method for the creation of critical-size mandibular defects in a porcine model, simulating a load-bearing situation., (Copyright © 2022 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

We have assessed the accuracy and clinical validation of virtual planning using a surgical template in 16 patients with hemifacial microsomia being treated by mandibular distraction osteogenesis. Virtual planning and simulation were first done on three-dimensional models. Distraction was simulated on the virtual model and the new morphology of the mandible was previewed. Both the position and direction of the distractor were calculated to achieve the optimal morphology. The templates were designed based on the virtual planning, and manufactured using a 3-dimensional printing technique. The template was designed to assist the surgeon to make the osteotomy and predrill the screw-holes to guide the distractor into position. The outcome was evaluated by comparing planned with postoperative outcomes. The osteotomy was made and the distractor implanted successfully under the guidance of the template in all patients. The linear and angular differences for the distractor were measured and reported using the root mean square deviation. There was no difficulty in using the templates. The largest linear root mean square deviation between the planned and the postoperative distractors was 0.93mm in the anteroposterior direction, and the largest in the horizontal plane was 4.64°. We suggest that the preoperative plan can be transferred accurately to a patient using the template., (Copyright © 2018. Published by Elsevier Ltd.)

Unilateral condylar hyperplasia is a rare disease that causes facial asymmetry as a result of excessive vertical or horizontal growth, or both, of the mandibular condyle. Investigation should address the patient's concerns, and establish whether the disease is active with the use of single positron emission tomography (PET). Proportional reduction of the condyle arrests active disease and restores mandibular height, and any residual asymmetry can be corrected according to conventional orthognathic principles. We recommend the use of 3-dimensional virtual planning for such complex movements. The rarity of the disease means that, to our knowledge, high-quality evidence is lacking and further research is needed., (Copyright © 2018 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The only cutting technique used for osteotomies in orthognathic surgery for many years has been a saw, but recently piezoelectric surgery has been introduced as a possible alternative. The aim of this study was to find out if piezoelectric surgery can be more comfortable for patients having orthognathic surgery. A total of 25 patients with dentofacial deformities (seven male and 18 female), were treated from January 2016 to September 2017. In 11 patients, osteotomies were made using a conventional saw, while in 14 a piezoelectric device was used. The variables assessed were: operating time, postoperative swelling, postoperative pain, and cutaneous sensitivity of the upper and lower lips. The duration of operation for the piezosurgery group was significantly longer than that for controls, but the patients had less swelling at all follow-up visits, and the difference was significant at the 30-day follow-up (p=0.045). Those who had piezosurgery had significantly less pain at the three-day follow up (p=0.035). There was a significant difference in cutaneous sensitivity only for the right side of the upper lip and only at the one-day follow-up. We conclude that piezoelectric surgery offers some advantages in lessening swelling and the perception of pain after orthognathic surgery, but further investigations are required., (Copyright © 2018 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Genioglossal advancement, which is one of the treatments for obstructive sleep apnoea, can be effective only if it contains enough genial tubercle for an osteotomy. The aim of this study was to establish the position of the genial tubercle and of the optimal osteotomy during genioglossal advancement. Twenty-four adult cadavers with intact bony mandibular structures were included. Five variables were measured: the width and height of the genial tubercle (GTW); the distance from its inferior border to the inferior border of the mandible (IGT-IBM); the distance from the superior border of the genial tubercle to the inferior border of the mandible (SGT-IBM); and the width of the intermental foramen (IMFW). The following mean (SD) (range) measurements were obtained: GTW 7.38 (1.43) (4.5-10.0); GTH 7.94 (1.45) (5.0-10.0); IGT-IBM 7.96 (2.29) (4.0-12.0); SGT-IBM 15.90 (2.29) (12.0-20.0); and IMFW 56.65 (6.44) (43.0-67.0) mm. Of the 24 cadavers, 22 showed evidence of optimal positioning when the osteotomy was placed 2mm higher than the SGT-IBM measured on the inner table. This suggests that an optimal osteotomy, which includes the genial tubercle, may be possible in most patients when the osteotomy is positioned 2mm higher at the SGT-IBM., (Copyright © 2018 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Our aim was to evaluate the efficacy of high condylectomy combined with orthodontic treatment for active unilateral condylar hyperplasia in 25 affected patients, by an analysis of the maxillary and mandibular changes on cone-beam computed tomography (CT). High condylectomy was the sole operative treatment. Variables that reflected the canting of the occlusal plane, the height of the maxillary complex, the buccolingual angulation of the maxillary first molar, the height of the ramus, the total length of the mandible, and the deviation of the chin were measured and compared between the two sides and between time intervals: preoperatively (T1) and the end of treatment (T2). The differences between time intervals in the deviation of the chin (p<0.001) and the canting of the occlusal plane (p<0.001) were significant, but there were no significant differences in the height of the ramus (p=0.476) and the total length of the mandible (p=0.838) between the affected and unaffected sides at T2. There were significant differences between time intervals in the buccolingual angulation on the unaffected side and the height of the maxillary complex on the affected side (p<0.001). Facial asymmetry was corrected and the occlusal plane was improved. In conclusion, high condylectomy as the sole operative treatment combined with orthodontic treatment can provide an alternative method for correction of facial asymmetry associated with active unilateral condylar hyperplasia., (Copyright © 2018 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Mandibular angle osteotomy (MAO) and mandibular angle splitting osteotomy (MASO) are the two main surgical approaches used to correct a square mandible for a desirable aesthetic appearance. However, there are concerns about the safety and accuracy of both procedures as they may lead to unsatisfactory results such as injury to the nerve. To achieve symmetry and security we designed and evaluated a 3-dimensional printed surgical template, which indicates the outer cortex splitting line of the MASO, and the curved cutting line of the MAO. We operated on 11 patients who had been diagnosed with broad mandibles using the assisted template. The mean duration of osteotomy, degree of numbness of the inferior alveolar nerve, and reduction in the width of the mandible (Go-Go) were recorded. The mandibular curve before and after operation was fitted to evaluate its accuracy. The results showed that mean duration of osteotomy and numbness of the nerve were reduced, and there was no significant difference between simulation and postoperatively. The mean (SD) reduction in the mandibular width was 15.2 (1.6)mm. The template facilitated accuracy and safety in both procedures., (Copyright © 2018. Published by Elsevier Ltd.)

Mandibular step osteotomy is a useful technique for large mandibular setbacks. We report a case of a patient who had a mandibular step osteotomy using a CAD/CAM-derived wafer for mandibular setback with reduction of the arch., (Copyright © 2017 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

For a sagittal split ramus osteotomy to be secure, the relation between the outer and inner contours of the cortex at the inferior border of the mandible is critical. The lowest point of the outer contour is not always immediately below that of the inner contour, and the former is placed more lingually than the latter in about a third of all cases. This tendency is much more noticeable in skeletal class I and II malocclusions than class III. It is therefore important to examine the lowest point of the inferior border in every case, and to carry the inferior part of the buccal cut on to the lingual side if necessary., (Copyright © 2017 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

We describe the use of anterior mandibular subapical setback osteotomy combined with bilateral sagittal split osteotomy in the treatment of selected patients with obstructive sleep apnoea (OSA). The technique enables maximal mandibular advancement, it alleviates pharyngeal narrowing, and minimises the alteration to the mid facial profile that is associated with traditional maxillomandibular advancement., (Copyright © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The aim of this study was to estimate skeletal and dental stability after maxillomandibular osteotomy with physiological positioning. Ten patients (7 men and 3 women) with skeletal mandibular prognathism were treated by conventional Le Fort I osteotomy for the maxilla and unfixed short lingual osteotomy for the mandible together with physiological positioning. We used cephalometric analysis to evaluate the skeletal and dental stability preoperatively, immediately after maxillomandibular osteotomy, and more than 1 year later. The immediately postoperative measurements for the SNA and the SN-palatal planes were 0.15° (p=0.67) and 1.0° (p=0.17), respectively. The positions of the anterior nasal spine, posterior nasal spine, and A point showed minimal changes 1 year postoperatively. The postoperative difference for SNB was 0.76° (p=0.04). Dental stability was apparent postoperatively. We conclude that reliable stability of both the maxilla and the mandible was achieved after maxillomandibular osteotomy with physiological positioning in patients with mandibular prognathism., (Copyright © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The aim of this study was to evaluate the postoperative stability of the surgery-first approach using intraoral vertical ramus osteotomy (IVRO). We retrospectively studied a sample derived from the patients who were treated by the surgery-first approach using a LeFort I osteotomy and IVRO for correction of class III dentofacial deformity from 2008 to 2012. Lateral cephalograms taken preoperatively and 2 days, 6 months, and 12 months postoperatively were traced, and the skeletal and dental variables at different time points were analysed. The study sample comprised 37 subjects, mean (SD) age 23 (4) years. The mean (SD) total duration of treatment including postoperative orthodontics was 14 (6) months, and surgical movement of the maxillary A point was 0.75 (1.3)mm anteriorly, and 0.21 (1.79)mm superiorly. The surgical change in the position of the maxillary first molar was 1.01 (1.57)mm superiorly. The mean (SD) movement of mandible was 11.15 (5.4)mm posteriorly at pogonion and 1.02 (1.79)mm inferiorly at menton. There were no significant change in maxillary skeletal variables during the first year postoperative period. The surgical relapse of mandible at pogonion was 0.63 (2.31) mm anteriorly (p=0.01), however, the relapse in superior direction at menton was 2.86 (1.39) mm with statistical significance (p=0.01). The total duration of orthodontic treatment with surgery-first was roughly 5 months shorter than conventional preoperative and postoperative orthodontic treatment. The surgery-first approach using IVRO is effective and predictable, and shortens the overall duration of treatment. Anterior relapse of the mandible was less than 1mm, and increased superior relapse can be compensated for with appropriate preoperative planning to provide a reliable outcome. This study was limited to 12 months' follow-up, and a long term follow-up study is indicated., (Copyright © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

In this randomised controlled clinical trial, 2 homogeneous groups of patients with facial asymmetry (n=10 in each) were treated by either classic or computer-assisted orthognathic corrective surgery. Differences between the 2 groups in the alignment of the lower interincisal point (p=0.03), mandibular sagittal plane (p=0.01), and centering of the dental midlines (p=0.03) were significant, with the digital planning group being more accurate., (Copyright © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Our aim was to investigate the effectiveness of piezoelectric surgery, where the osteotomy is made using ultrasonic vibration, in reducing surgical complications after bilateral sagittal split osteotomy (BSSO). Fifty-nine patients with skeletal mandibular prognathism who had mandibular setback with BSSO between January 2009 and April 2011 were included in the study. Piezosurgery was used in 29 cases, and the bone was split using a separator. In the remaining 30 cases, a Lindeman bur was used for the osteotomy and a chisel was used to split the bone. The amount of intraoperative bleeding and the Semmes Weinstein test scores were used as objective variables to evaluate the degree of neurosensory disturbance, and sex, age, use of piezosurgery, degree of setback, operating time, and method of fixation were used as explanatory variables. We used analysis of covariance (ANCOVA) to assess the significance of differences. Intraoperative bleeding was significantly less with age (p=0.003), and longer when operating time was prolonged (p=0.017), and was not influenced by the use of piezosurgery. The Semmes Weinstein test score significantly increased with age (p=0.01), and was significantly greater when piezoelectric surgery was used (p=0.008), and at 3 months, there were signs of more neurosensory disturbance in older patients and those who had had piezoelectric surgery. In this retrospective non-random study piezoelectric surgery reduced neither blood loss nor the incidence of neurosensory disturbance in BSSO., (Copyright © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

We describe the strategy of physiological positioning, which we regard as a new alternative treatment to conventional orthognathic operations, and treated 18 patients with skeletal mandibular prognathism using it. The positions of SNB, FMA, and Me were measured postoperatively to assess skeletal stability, changes in the angle and perpendicular length of the upper and lower central incisors were measured to assess dental stability, and we confirmed that both skeletal and dental stability were excellent. The width to which the jaw could be opened recovered early, and we saw only one case of disorder of the temporomandibular joint. Short lingual osteotomy with physiological positioning is an effective new approach to the treatment of deformities of the mandible., (Copyright © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Some cases in orthognathic surgery present with large discrepancies between the skeletal pattern and the occlusion. If there is little or no sagittal dental discrepancy, but the mandibular basal bone is prognathic, surgical correction can be critical. We describe a two-step procedure to treat these patients. The first step is to adapt the lower alveolar bone to the position of the chin. Distraction osteogenesis in the anterior dentoalveolar mandibular region carries the lower incisors to the same level as the chin. A one-tooth space is opened in the distraction area to obtain a full negative over-jet. Bimaxillary osteotomy can be used to correct class III dentoskeletal malocclusion. Five patients aged 20-40 years have been operated on during the last 2 years. The first step creates harmony between the chin and lower lip, together with a negative over-jet and a true prognathic profile. The class III malocclusion is corrected with a bimaxillary osteotomy. Our two-step plan achieves good occlusion and profile in patients with severe discrepancies between their occlusion and the position of the chin. Dental implants can then be inserted into the gaps left by distraction, which results in a third bicuspid on each side of the mandible., (Copyright © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Our aim was to evaluate the postoperative stability associated with differing degrees of mandibular setback and their relations after intraoral vertical ramus osteotomy (IVRO). We planned a retrospective cohort study of 94 patients (mean age (range) 23 (18-46) years) selected from a larger group who had been diagnosed with mandibular prognathism with or without facial asymmetry and who had mandibular setback by IVR osteotomy from 2004 to 2009. The preoperative, 7-day, and 12-month postoperative lateral cephalographs were measured to find out the degree of movement, and the vertical and horizontal positions of menton and pogonion were compared at different time points to measure stability. The mean (SD) setback was 10.5 (5.1) mm, with 0.8 (1.1) posterior relapse at 12 months. The mean surgical change of menton vertically was 3.0 (3.0) mm superiorly, with an additional 1.3 (1.05) mm at 12 months. The amount of posterior relapse was less as the amount of setback increased but not significantly so. The amount of setback therefore has minimal effects on anterior relapse, and cannot be considered singly as a variant that affects the degree of stability. The risk of anterior relapse is low even with a substantial degree of mandibular setback, so overcorrection is not necessary with the IVR osteotomy., (Copyright © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

The aim of this study was to evaluate postoperative changes in proximal segments and condyles on the transverse plane after intraoral vertical ramus osteotomy. This is a retrospective study that included 200 subjects operated on, from 2003 to 2010, from whom we compared preoperative and postoperative (7 days, and 1, 3, 6, and 12 months) submentovertex radiographs. Postoperative positional changes in the condyles showed a mean (SD) of 15.05 (8.97)° lateral rotation, which slowly returned towards the original position. However, 4.53 (6.03)° lateral rotation remained on the postoperative radiographs at 1 year. There were no remarkable differences in intercondylar distance at any given time interval, which showed pure rotation of condyles without any bodily shift. The length of horizontal overlapping was also increased after operation, and was later decreased by 48% on postoperative radiographs at 1 year through the remodelling process. Condyles had rotated laterally without a lateral shifting movement only after intraoral vertical ramus osteotomy. Further studies to evaluate the physiological effects of rotational movement of the condyles after the operation in patients with symptoms in the temporomandibular joint are indicated., (Copyright © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Mandibular setback reduces space in the pharyngeal airway, and it has been suggested that it might induce sleep-disordered breathing. We report on its effects on space in the pharyngeal airway and respiratory function during sleep. We studied 78 patients (29 men and 49 women) in whom skeletal class III malocclusions had been corrected. The mean (range) age at operation was 24 (16-38) years and body mass index (BMI) 21.4 (16.1-30 .9)kg/m(2). Morphological changes were evaluated on lateral cephalograms taken three times: preoperatively, a few days postoperatively, and more than 6 months postoperatively. Overnight arterial oxygen saturation (SpO2) was measured by pulse oximetry 6 times: preoperatively, and on days 1, 3, 5, and 7, and 6 months postoperatively; oximetric indices were calculated. Those immediately after mandibular setback were significantly worse than those preoperatively, although they gradually improved. There were positive correlations between BMI and oximetric indices, and little association between changes in mandibular position and oximetric indices. There was no evidence of sleep-disordered breathing 6 months after mandibular setback because most patients adapt to the new environment for respiratory function during sleep. However, some (particularly obese) patients may develop sleep-disordered breathing just after mandibular setback. In such patients attention should be paid to respiratory function during sleep in the immediate postoperative period, and careful postoperative follow-up is needed., (Copyright © 2012 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)