Inferior alveolar nerve reconstruction in extensive mandibular resection: Technical notes.

The inferior alveolar nerve (IAN) is a sensitive branch of the mandibular nerve innervating the lower lip, the chin, the buccal mucosa and the teeths. Lesions of the IAN are reported to occur in the 64,4% of maxillo-facial procedures, leading to anesthesia, hypoestesia and/or neurogenic discomfort. An extensive segment of the nerve can be moreover removed during mandibular resection for benign or malignant pathologies. Nervous grafts can be used in these cases to restore the nerve continuity. In order to optimize the procedure and to allow a concomitant mandibular osseous reconstruction, the Authors identified several standardized steps. The technique described allows to perform confortable and safe nervous anastomoses and to reduce the risk of damage and tension during the flap insetting phases.

Piezoelectric Cutting Devices for Osteotomy in Temporomandibular Joint Condylectomy.

Condylar hyperplasia is an alteration in mandibular growth that can cause facial asymmetry and occlusal changes that usually affect the aesthetics and function of patients. To date, condylectomy for its part remains a key part of the treatment. Although there are still controversies regarding the amount of bone to remove and the surgical approach, there are still other concerns, such as finding the benefit in terms of intraoperative safety and postoperative results with different cutting devices, including the use of piezoelectric, which is increasing its use in the maxillofacial field. This is why the main objective of this study is to compare the results found in medical records and databases of condylectomy procedures performed between 2017 and 2019 with different cutting devices.

Fully Automatic Robot-Assisted Surgery for Mandibular Angle Split Osteotomy.

With the development of computer-assisted surgery, preoperational design is detailed in software. However, it is still a challenge for surgeons to realize the surgical plan in the craniofacial surgery. Robot-assisted surgery has advantages of high accuracy and stability. It is suitable for the high-stress procedures like drilling, milling, and cutting. This study aims to verify the feasibility for automatic drilling without soft tissues in model test based on an industrial robot platform.This study chose the data from digital laboratory in Shanghai 9th People's Hospital. The mandibular was reconstructed in software and surgical plan was also designed. Then, the coordinate data was input to the robot's software and matrix conversion was calculated by 4 marked points. The trajectory generation was calculated by inverse kinematics for target coordinates and robot coordinates. The model was fixed and calibrated for automatic drilling. At last, the accuracy was calculated by optic scanning instrument.The installment and preparation cost 10 minutes, the drilling procedure cost 12 minutes. The outside position error was (1.71 ±â€Š0.16) mm, the inside position error was (1.37 ±â€Š0.28) mm, the orientation error was (3.04 ±â€Š1.02)°. Additionally, a total of 5 beagles were tested, with an accuracy error of (2.78 ±â€Š1.52) mm. No postoperative complications occurred.This is the first study reported for robot-assisted automatic surgery in craniofacial surgery. The result shows it is possible to realize the automatic drilling procedure under the condition of no interference like soft tissues. With the development of artificial intelligence and machine vision, robot-assisted surgery may help surgeons to fulfill more automatic procedures for craniofacial surgery.

Is Bilateral Sagittal Split Osteotomy of the Mandible With no Step Possible? A Modification in the Technique.

The mandibular ramus sagittal osteotomy is a usual procedure used to correct deformities of the lower third of the face. Modifications of the procedure will be presented to avoid the presence of palpable gap at mandibular body, easily seen in greater movements.

Clinical Application of Temporary External Fixator for Immediate Mandibular Reconstruction.

Immediate mandibular reconstruction is always necessary for the patients receiving segmental mandibulectomy to recover the facial contour and function of occlusion. When 3D modeling is unavailable, temporary external fixator is necessary to maintain the occlusion relationship and facial contour. In this study, we introduce the clinical application of temporary external fixator for immediate mandibular reconstruction in patients receiving segmental mandibulectomy, which consists of 2 anchor claws, 2 all-round retentive arms, and 1 central locking structure. From August 2016 to September 2017, temporary external fixator was applied in 13 patients. Clinical data of gender, age, surgical procedure, duration of operation, and clinical outcomes were recorded and analyzed. Among the 13 patients, there were 4 men and nine women whose ages ranged from 21 to 64 (mean 47.7) years old. There were 9 benign and 4 malignant lesions. All lesions expended at the buccal side of mandible. 12 fibular flaps and 1 vascularized iliac bone graft were used. The mandibular defect ranged from 6 to 14 (mean 10) cm. The operation duration of surgery ranged from 5 to 10 (mean 7) hours. All flaps survived with primary healing. The occlusion and facial contour were good, without significant changes of the length of mandibular body and width of mandible before and after surgery. No functional sequelae were noted at the donor sites. From these results, the temporary external fixator is easy to operate; the surgical procedure is simple and time-saving for surgeon when 3D modeling is unavailable. The indication for temporary external fixator usage is the mandibular lesion growing outward to cheek soft tissue.

Contour Restoration of Over-Resected Mandibular Angle and Lower Border by Reduction Mandibuloplasty Using Three-Dimensional Planning and Computer-Aided Design and Manufacturing Custom-Made Titanium Implants.

OBJECTIVE: The purpose of this clinical report was to introduce a new methodology for contour restoration of the over-resected mandible by reduction mandibuloplasty using 3-dimensional (3D) planning and computer-assisted design and manufacturing (CAD-CAM) custom-made titanium implants. PATIENT AND METHOD: A 20-year-old male patient had undergone reduction of the zygoma and mandibular angle and lower border for esthetic reason 1 year ago at a private clinic. However, he was not satisfied with surgical outcome and wanted to restore his original facial volume and contour. To assess the volume and dimension of resected bone, 3D-computed tomography (3D-CT) data at the original stage was superimposed with postsurgical CT. For restoration of the malar prominence, porous polyethylene malar implants with extensions into the lateral malar region (Medpor) were placed and fixed with microscrews. Custom-made titanium implants were fabricated for contour restoration of the mandibular angle and lower border using CAD-CAM technology (iDDA, Daegu, South Korea). Two-piece design per each titanium implant was adopted for easy placement and avoidance of tissue damage during placement. Thin buccal extension was incorporated for placement of screw holes. Location, direction, and length of bicortical screws were planned to avoid damage of the inferior alveolar nerve. RESULT: With the help of 3D planning and CAD-CAM technology, rigid fixation of the custom-made titanium implants into the mandibular angle and lower border successfully restored the contour of over-resected mandible to the original state. CONCLUSION: When over-resection by reduction mandibuloplasty becomes an issue, this method may be an effective treatment option for contour restoration of over-resected mandibular angle and lower border.

Evaluation of Intersegmental Displacement After Mandibular Setback Split Ramus Osteotomy Using Modified L-Shaped Monocortical Plate: Cone-Beam Computed Tomography Superimposition.

PURPOSE: The purpose of the current study is to compare intersegmental displacements after mandibular setback sagittal split ramus osteotomy (SSRO) using 4 types of osteosynthesis methods. PATIENTS AND METHODS: This is a retrospective study of 53 subjects who presented underwent bilateral setback SSRO at Pusan National University Hospital from January 2009 to December 2013. The subjects were divided into 4 groups according to the osteosynthesis method applied: group A-modified L-type monocortical plate; B-conventional miniplate; group C-bicortical screws; group D-metal and absorbable screws. To obtain the intersegmental displacement, the mean of the differences of the 3-dimensional from T0 (2 days after surgery) to T1 (6 months after surgery) was calculated for the right and left condylar heads (condylion, Cd) and the right and left coronoid processes (Cps) using 3-dimensional imaging software (Ondemand 3D; Cybermed Co, Seoul, Korea). RESULTS: For the condylion in the x, y, z coordinate system, in group A, there were significant differences in the y-axis for the right and left Cd; in group B, significant differences in the y-axis for the right Cd and in the y- and z-axes for the left Cd; in group C, no significant differences in the axis for the Cd; and in group D, there were significant differences in the y- and z-axes for the right Cd and in the x- and y-axes for the left Cd. For the Cps, the results are not much different from the condylion movement in all group. CONCLUSION: In the current study, group C manifested the greatest displacement for the healing period. Group A did not show the significant difference to group B. In view of these results, modified L-shaped monocortical plate can be applied for osteosynthesis effectively.

Osteotomy Site Grafting in Bilateral Sagittal Split Surgery With Bioactive Glass S53P4 for Skeletal Stability.

In orthognathic surgery, the aim of the treatment is to achieve a good occlusion and a satisfying aesthetic outcome. In large mandibular advancements insufficient healing at the mandibular inferior border may lead to loss of support for the overlaying tissue at the osteotomy site. Augmentation can be performed to improve stability, bone regeneration, and the aesthetic outcome. The purpose of this prospective clinical study was to evaluate the use of a novel material for this indication; granules of the antibacterial, osteoconductive, and slowly resorbing bioactive glass S53P4 as filling material in large mandibular advancement in bilateral sagittal split osteotomies. The authors treated 25 patients who underwent bilateral sagittal split osteotomies due to class II dentoskeletal deformities. The mandibular osteotomy site defects (8-15 mm) were augmented with bioactive glass S53P4. The average clinical follow-up was 33 months and the average radiological follow-up with cone beam computerized tomography was 24 months. The clinical and radiological results were good with regard to healing, bone regeneration, and stability of the osteotomy sites. The recontouring of the inferior mandibular border provided a good soft tissue support followed by an excellent aesthetic outcome in 96% of the osteotomy sites. The occlusion was stable in 88% of the patients. The authors' results show that bioactive glass S53P4 is a safe grafting material for osteotomy site defects in significant mandibular advancements with reliable bone regeneration, providing long-term stability at the osteotomy site and at the inferior mandibular border.

Robot-Assisted Surgery for Mandibular Angle Split Osteotomy Using Augmented Reality: Preliminary Results on Clinical Animal Experiment.

Mandibular angle split osteotomy (MASO) is a procedure widely used for prominent mandibular angles. However, conventional mandibular plastic surgery is invasive and high risk. It may induce postoperative neurosensory disturbance of the inferior alveolar nerve, fractures and infection due to the complexity of the anatomical structure and the narrow surgical field of view. The success rate of MASO surgery usually depends on the clinical experience and skills of the surgeon. To evaluate the performance of inexperienced plastic surgeons conducting this surgery, a self-developed and constructed robot system based on augmented reality is used. This robot system provides for sufficient accuracy and safety within the clinical environment. To evaluate the accuracy and safety of MASO surgery, an animal study using this robot was performed in the clinical room, and the results were then evaluated. Four osteotomy planes were successfully performed on two dogs; that is, twenty tunnels (each dog drilled on bilaterally) were drilled in the dogs' mandible bones. Errors at entrance and target points were 1.04 ± 0.19 and 1.22 ± 0.24 mm, respectively. The angular error between the planned and drilled tunnels was 6.69° ± 1.05°. None of the dogs experienced severe complications. Therefore, this technique can be regarded as a useful approach for training inexperienced plastic surgeons on the various aspects of plastic surgery. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Is the piezoelectric device the new standard for facial osteotomies?

Piezoelectric devices are commonly used in all areas of maxillofacial surgery. Initially applied in preprosthetic surgery, they have steadily become a common practice in major surgery of the facial skeleton, including maxillary and mandibular osteotomies, temporomandibular joint surgery, orbital surgery, craniofacial procedures and rhinoplasty. We will review the current medical literature and establish the "state of the art" of piezosurgery in orthognathic surgery, TMJ surgery and rhinoplasty.

Commissurotomy.

This step-by-step feature provides a pictorial description of the commissurotomy procedure. Commissurotomy can be performed to increase surgical access to the caudal oral cavity for procedures such as total mandibulectomy, caudal mandibulectomy, and surgical access to the mandibular ramus.

Finite Element Evaluation of Different Osteosynthesis Variations That Used After Segmental Mandibular Resection.

PURPOSE: The purpose of this study was to evaluate the effect of different reconstruction plates and screw combinations on stress distribution of segmental resected mandibles using finite element analysis. METHODS: Lateral (L) and lateral-central (LC) defects were simulated by a computer aided design modeling. The straight (s) and angular (a) titanium locking reconstruction plates of 2.5 mm (12 holes for L defects and 16 holes for LC defects) were modeled. Each screw was 2.5 mm in diameter and 10 mm in length. A total of 20 different screw placement combinations were created. The bite force used in the present model was a unilateral molar clench. The data obtained from finite element analysis were recorded as von Mises, maximum principle and minimum principle stress values. RESULTS: It was observed that stress values on neck of screw were higher for screws close to the resection area. When the first screw was loosened, the stress on the plate body and the remaining screws increased. Principle stress values were within the tolerance limits of the bone. CONCLUSION: The highest stress is observed in the screws nearest to the resection edge. Therefore, it is very important to place a screw adjacent to the resection edge.

Transoral Fixation of Bicortical Screws Is Safe and Feasible for Lower Jaw Osteotomies.

PURPOSE: Transoral placement of bicortical screws is a rigid fixation method in orthognathic surgery that is used less often than transbuccal placement. The aim of this study was to examine the postoperative outcome of transoral bicortical screw insertion during orthognathic surgery and to compare it with the more common transbuccal fixation technique. MATERIALS AND METHODS: A retrospective cohort study was conducted. Clinical files of orthognathic surgery patients operated on from January 2010 through December 2012 were reviewed. Screw insertion approach (transoral vs transbuccal) was examined as a predictive variable for postoperative complications (hardware removal and infection). Type of surgery, fibrin sealant, preoperative third molar removal, and patient age and gender were analyzed as potential risk factors. Descriptive and bivariate statistics and regression analyses were performed. RESULTS: Of the 606 patients whose cases were reviewed, 509 patients (185 men; mean age, 26.3 ± 11.1 yr) met the inclusion criteria. Most presented with a Class II malocclusion (84.5%). A transbuccal approach was used in 27.5% of cases, leading to a screw-related infection of 6.3%. Patients treated with a transoral technique (72.5%) had fewer infections (3.5%), but this was not statistically relevant. Screw removal was indicated in 3.3% of patients. Screw placement using the transoral and transbuccal approaches was performed in 3.0 and 4.2% of patients, respectively. Infection and screw removal rates did not differ significantly between fixation techniques (P = .16 and P = .49, respectively). CONCLUSION: The present findings showed an overall low rate of screw removal and infection secondary to bicortical screw insertion during orthognathic surgery. The postoperative outcome was similar for the transoral and transbuccal approaches.

Bone healing after biodegradable mini-plate fixation.

PURPOSE: To compare bone healing in mandibular vertical body osteotomies (MVBO) after fixation with a resorbable 2.0mm-profile fixation system in the first and third postoperative months in rabbits. METHODS: Twenty hemimandibles of ten rabbits were divided into two groups according to duration of resorbable fixation-one or three months. The MVBOs were performed and one four-hole, resorbable, 2.0mm mini-plate fixation system was used on each side. The computed tomography (CT) scans, scanning electron microscopy (SEM), and histomorphometric outcomes of groups I and II were compared. RESULTS: Significant differences were found between the one- and three- month assessments in terms of newly formed bone ratio values (p<0.05). There was more new bone formation at the third month on both the CT and histomorphometric examinations. A better adaptation of the bone tissues to the resorbable mini-plate and screws was observed on SEM at three months. CONCLUSION: The resorbable mini-plates provided a fixation stable enough to allow immediate oral alimentation and callus formation in both groups.

Bone healing after biodegradable mini-plate fixation

ABSTRACT PURPOSE: To compare bone healing in mandibular vertical body osteotomies (MVBO) after fixation with a resorbable 2.0mm-profile fixation system in the first and third postoperative months in rabbits. METHODS: Twenty hemimandibles of ten rabbits were divided into two groups according to duration of resorbable fixation-one or three months. The MVBOs were performed and one four-hole, resorbable, 2.0mm mini-plate fixation system was used on each side. The computed tomography (CT) scans, scanning electron microscopy (SEM), and histomorphometric outcomes of groups I and II were compared. RESULTS: Significant differences were found between the one- and three- month assessments in terms of newly formed bone ratio values (p<0.05). There was more new bone formation at the third month on both the CT and histomorphometric examinations. A better adaptation of the bone tissues to the resorbable mini-plate and screws was observed on SEM at three months. CONCLUSION: The resorbable mini-plates provided a fixation stable enough to allow immediate oral alimentation and callus formation in both groups.

[Orthognathic surgery: surgical failures and complications]. / Chirurgie orthognathique : échecs chirurgicaux et complications∗.

Orthognathic surgery procedures mark the endpoint of lengthy orthodontic-surgical preparations and herald the completion of treatment for patients and their families. The main types of procedure are full maxillary Le Fort I osteotomies, mandibular osteotomies and chin surgery. To ensure a successful outcome, all require a favorable environment and extreme technical skill. But, like all surgical operations, they are also subject to peri- and post-operative complications resulting from treatment hazards or errors. Whatever the cause, surgical complications can entail failures in the management of the malformation. By seeking to understand and analyzing these complications, we can already help to prevent and reduce the contingent risks of failure.

Accuracy of experimental mandibular osteotomy using the image-guided sagittal saw.

The aim of this study was to perform an objective assessment of the accuracy of mandibular osteotomy simulations performed using an image-guided sagittal saw. A total of 16 image-guided mandibular osteotomies were performed on four prefabricated anatomical models according to the virtual plan. Postoperative computed tomography (CT) image data were fused with the preoperative CT scan allowing an objective comparison of the results of the osteotomy executed with the virtual plan. For each operation, the following parameters were analyzed and compared independently twice by two observers: resected bone volume, osteotomy trajectory angle, and marginal point positions. The mean target registration error was 0.95±0.19mm. For all osteotomies performed, the mean difference between the planned and actual bone resection volumes was 8.55±5.51%, the mean angular deviation between planned and actual osteotomy trajectory was 8.08±5.50°, and the mean difference between the preoperative and the postoperative marginal point positions was 2.63±1.27mm. In conclusion, despite the initial stages of the research, encouraging results were obtained. The current limitations of the navigated saw are discussed, as well as the improvements in technology that should increase its predictability and efficiency, making it a reliable method for improving the surgical outcomes of maxillofacial operations.

Biomechanical Evaluation of Different Fixation Methods for Mandibular Anterior Segmental Osteotomy Using Finite Element Analysis, Part One: Superior Repositioning Surgery.

The aim of the current study was to comparatively evaluate the mechanical behavior of 3 different fixation methods following various amounts of superior repositioning of mandibular anterior segment. In this study, 3 different rigid fixation configurations comprising double right L, double left L, or double I miniplates with monocortical screws were compared under vertical, horizontal, and oblique load conditions by means of finite element analysis. A three-dimensional finite element model of a fully dentate mandible was generated. A 3 and 5 mm superior repositioning of mandibular anterior segmental osteotomy were simulated. Three different finite element models corresponding to different fixation configurations were created for each superior repositioning. The von Mises stress values on fixation appliances and principal maximum stresses (Pmax) on bony structures were predicted by finite element analysis. The results have demonstrated that double right L configuration provides better stability with less stress fields in comparison with other fixation configurations used in this study.

Biomechanical Evaluation of Different Fixation Methods for Mandibular Anterior Segmental Osteotomy Using Finite Element Analysis, Part Two: Superior Repositioning Surgery With Bone Allograft.

In this study, the biomechanical behavior of different fixation methods used to fix the mandibular anterior segment following various amounts of superior repositioning was evaluated by using Finite Element Analysis (FEA). The three-dimensional finite element models representing 3 and 5 mm superior repositioning were generated. The gap in between segments was assumed to be filled by block bone allograft and resignated to be in perfect contact with the mandible and segmented bone. Six different finite element models with 2 distinct mobilization rate including 3 different fixation configurations, double right L (DRL), double left L (DLL), or double I (DI) miniplates with monocortical screws, correspondingly were created. A comparative evaluation has been made under vertical, horizontal and oblique loads. The von Mises and principal maximum stress (Pmax) values were calculated by finite element solver programme. The first part of our ongoing Finite Element Analysis research has been addressed to the mechanical behavior of the same fixation configurations in nongrafted models. In comparison with the findings of the first part of the study, it was concluded that bone graft offers superior mechanical stability without any limitation of mobilization and less stress on the fixative appliances as well as in the bone.