Does the use of intraoperative frozen section of bone marrow from the cut end of the mandible help assess the adequacy of bone margins following mandibulectomy for oral cancer?

BACKGROUND: The adequacy of the cut end of the mandible following a segmental mandibulectomy done for oral cancer intraoperatively is at times assessed using a frozen section (FS) of the bone marrow (BM) at the cut ends. The study aimed to assess its utility to guide the intraoperative decision on the adequacy of bony margins. MATERIALS AND METHODS: All patients with oral squamous cell carcinoma (OSCC) who underwent segmental mandibulectomy from January 2012 to December 2021 at our institute and for whom intraoperative FS of BM was utilized were included. We analyzed the sensitivity, specificity, and positive and negative predictive value (PPV, NPV) of this in predicting positive bone margins. RESULTS: A total of 457 patients were included in the study. The majority of the cases were per premium cases (n = 372, 81.4%). The median age of the cohort was 52 years (range: 22-80 years). Most patients had T4 disease (n = 406, 88.8%). On FS, BM was positive in only 18 patients (3.9%) for whom the bone margin was revised. BM biopsy report in the final histopathology was positive in 12 patients (2.2%). The sensitivity, specificity PPV, and NPV were 52.3%, 98.65%, 64.7%, and 97.7% respectively. No factors predicting BM positivity on FS could be identified in this cohort. CONCLUSIONS: The BM FS was positive in only a small percentage of patients, and it helped in reducing the bone margin positivity rate from 3.9% to 2.2% only. Hence the intraoperative BM FS seems to have limited utility as seen from our study.

Mandibular Body Osteotomy Combined with Sagittal Split Ramus Osteotomy for the Treatment of Severe Skeletal Class â ¢ Malocclusion with Ankylosed Teeth.

This study presents a combination of 2 different surgery procedures performed on the mandible as part of the treatment aiming to improve the facial profile and occlusal function of patients with severe skeletal class Ⅲ malocclusion and bilateral edentulous gaps. The teeth next to the edentulous gaps were found to be ankylosed. Mandibular setback by bilateral sagittal split ramus osteotomies and mandibular body osteotomies, combined with Le Fort Ⅰ level maxillary advancement were performed, since the chief complaint of the patient was a concave profile. As a result, the skeletal class Ⅲ malocclusion had been corrected, a satisfying facial profile had been achieved, and no apparent adverse effect was found. Thus, it has been proved that the combination of sagittal split ramus osteotomy and mandibular body osteotomy is available for correcting skeletal class Ⅲ malocclusion.

Aggressive Late Recurrence of a Calcifying Epithelial Odontogenic Tumor: Surgical Refinements Based on New Technologies.

A calcifying epithelial odontogenic tumor is a rare, benign odontogenic neoplasm. Surgical treatment is the option, and late recurrence is very rare. Radiologically, the lesions are commonly present scattered calcifications. This case report details a 64-year-old female patient with a recurrence of a right mandibular calcifying epithelial odontogenic tumor 2 decades after successful initial surgical removal. A segmental mandibulectomy and immediate reconstruction were performed using a planned vascularized free fibula flap with virtual surgery, custom reconstruction plate, and intraoperative computed tomography. Modifications were made to the design of the reconstruction plate to improve the cervicofacial profile and subsequent rehabilitation with dental implants. Fully guided implant surgery with point-of-care manufacturing protocol was done to improve prosthetically driven implant planning. The case presented highlights the usefulness of new technologies for mandibular reconstruction with the free fibula flap and the concept of point-of-care with technical notes that increase precision and reduce morbidity in implant-supported rehabilitation.

Double Chin Concerns after En Bloc Mandibular U-Shaped Osteotomy: Submental-Cervical Soft Tissue Changes and Anterior Belly of Digastric Muscle Assessment.

OBJECTIVE: To assess submental-cervical soft tissue changes after en bloc mandibular U-shaped osteotomy and examine alterations in the anterior belly of digastric muscle (ABDM). METHODS: A retrospective study analyzed 20 patients who underwent en bloc mandibular U-shaped osteotomy from 2018 to 2023. Preoperative (Tp) and long-term follow-up (Tf) CT data were collected for analysis, measuring mandibular volume, soft tissue thickness at menton (Mes) and cervicale (C), and ABDM parameters (length, cross-sectional area (CSA), volume, distance from centroid point to the mandibular margin). Correlation analyses were performed to investigate the connection between soft tissue thickness changes, ABDM changes, and mandibular osteotomy volume. RESULTS: Long-term follow-up revealed a significant increase in soft tissue thickness at the Mes and C points after U-shaped mandibular osteotomy, especially at the C point. The adaptive length of ABDM decreased, CSA increased, and volume decreased, but the ABDM centroid point shifted downward relative to the mandibular margin, indicating drooping protrusion. The increment of soft tissue thickness was moderately positively correlated with the amount of osteotomy, and the decrement of ABDM length and volume were slightly positively correlated with the amount of osteotomy. CONCLUSION: The degree of soft tissue relaxation after U-shaped osteotomy is related to the extent of osteotomy. Notably, the protrusion of ABDM relative to the mandibular margin affects submental-cervical contour aesthetics. Prior to U-shaped osteotomy, it is crucial to assess the soft tissue condition of the patient's lower face, and the individualized design of the osteotomy volume should be carried out cautiously and safely. LEVEL OF EVIDENCE IV: 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 .

Factors affecting unusual postoperative vertical downward movement of mandible after surgery-first approach using intraoral vertical ramus osteotomy.

BACKGROUND: In very rare cases, patients who have undergone surgery-first approach with intraoral vertical ramus osteotomy (IVRO) exhibit unusual downward movements of mandible even up to 1-year post surgery, which makes it difficult for orthodontists to stabilize the occlusion during the postoperative orthodontic period. The aim of this study was to identify factors affecting the unusual downward movement of the mandible 1-year after the surgery-first approach using IVRO, while focusing on cephalometric values. METHODS: This retrospective cohort study sample was divided into two groups based on the amount of vertical movement of the B-point 1-year post surgery (Group S, predictable upward movement; Group U, unpredictable downward movement greater than 2 mm). To evaluate cephalometric changes between the two groups, cephalograms were obtained before surgery, 1 day after surgery, 1 month after surgery, and 1 year after surgery. The data were analyzed using the independent t-test, Mann-Whitney U test with Bonferroni correction, Pearson correlation analysis, and multiple regression analysis. RESULTS: At the initial examination, Group U showed a shallower anterior overbite. The vertical surgical change in the B-point was statistically different between the two groups (p < 0.001), indicating that group U exhibited more upward movement of the mandible during surgery. Group U showed significant downward movement of the mandible 1 month after surgery, and this finding persisted until 1 year postoperatively. Clockwise rotation of the mandible was also observed. Surgical vertical movement of the B-point showed a strong correlation with postoperative vertical movement of mandible (r = -0.674; p < 0.001) along a linear relationship, indicating that the amount of postoperative vertical downward movement of the mandible increased as the amount of surgical upward movement of the B-point increased (R2 = 0.449; p < 0.001). CONCLUSIONS: This study revealed that unusual downward movement of the mandible after a surgery-first approach using IVRO is correlated with the amount of upward movement during the surgery. When planning surgery, in cases in which a significant upward movement of the mandible is anticipated, orthodontists should prepare for the possibility of subsequent unusual downward movement and a tendency for the anterior overjet to decrease during the postoperative orthodontic period.

In regard to Castagnola et al. (doi: 10.1186/s12903-023-03050-7).

We are grateful to the authors of the study by Castagnola et al., which sought to ascertain the prevalence of tooth necrosis in patients undergoing mandibulotomy or mandibulectomy for head and neck cancer. In order to prevent surgical problems, the researchers suggested doing root canal therapy on the teeth next to the surgical site prior to surgery. Although the results offer insightful information about tooth necrosis in patients with head and neck cancer who have had mandibulotomies or mandibulectomy, we would like to voice our concerns about the reported data in order to give a stronger basis for future studies in this field.

In reply to the letter to the editor regarding "Clinical outcomes of teeth adjacent to the site of mandibulotomy or mandibulectomy in patients with head and neck cancer: results from a multidisciplinary mono-institutional head and neck tumor board".

This paper aims to reply to Somay et al., regarding their comment to a previous paper from our group, titled "Clinical outcomes of teeth adjacent to the site of mandibulotomy or mandibulectomy in patients with head and neck cancer: results from a multidisciplinary mono-institutional head and neck tumor board".The following concerns were addressed: 1) Within the limits of a case series, mandibulectomy might be considered a risk factor for the loss of tooth vitality as well as mandibulotomy. 2) Root canal therapy before surgery on the teeth adjacent to the surgical site could be an appropriate strategy, although in some cased it may involve teeth which are not destinate to have endodontic complications. 3) Dose-volume data of the included teeth were provided: the impact of radiotherapy (RT) as a confounding factor seems not to be as relevant as Somay et al. have pointed out.

Impact of Mandibular Angle Osteotomy Using a Geometric Mathematical Design on the Aesthetic Osteotomy Line: A Retrospective Observational Study.

BACKGROUND: Mandibular angle osteotomy (MAO) is a frequently described technique in Eastern females. The success hinges on the precise positioning of the osteotomy line. The geometric mathematical method is viable. Therefore, we explored the impact of mandibular angle osteotomy using aesthetic standards and printed digital osteotomy templates (DOTs) on the aesthetic osteotomy line. METHODS: This retrospective observational study included female patients with prominent mandibular angle (PMA) who underwent MAO at our hospital between January 2020 and March 2021. Thirty-three female patients were included, 22 in the DOTs group using new DOTs, and 11 in the traditional group using traditional free-hand techniques. RESULTS: Regarding the width of the excised bone, the postoperative deviation from the preoperative plan was not significant in the DOTs group (0.5 ± 0.3 mm, P > 0.05), while the deviation was significant for the traditional group (2.5 ± 1.2 mm, P<0.05). The preparation time was longer in the DOTs group than in the traditional group (82 ± 11 vs. 53±4 min, P < 0.001). The osteotomy time and the operation time were shorter in the DOTs group than in the traditional group (osteotomy: 54 ± 5 vs. 73 ± 6 min; preparation: 124 ± 10 vs. 169 ± 13 min; both P < 0.001). The Likert (4.0 ± 0.5 vs. 1.0 ± 0.6, P = 0.006) and FACE-Q scores (17.5 ± 1.7 vs. 15.6 ± 1.3, P = 0.029) were higher in the DOTs group. CONCLUSIONS: The new method of positioning the new aesthetic osteotomy line based on geometric analysis might provide a possible osteotomy method that strongly suggests effectiveness, safety, individualization, and accuracy, with a shorter operation and higher patient satisfaction. LEVEL OF EVIDENCE IV: 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 .

Redefining Mandibular Sub-units: The "ABC" Classification and Surgical Strategies for Lower Face Contouring.

BACKGROUND: In east Asia, lower face contouring surgeries including reduction mandibuloplasty and genioplasty are the most popular aesthetic craniofacial surgeries. Conventional selection of surgical strategies mainly relied on the visual judgment of the mandibular angle, without overall assessment of the mandibular sub-units. Furthermore, only a few studies offered quantitative assessment of the mandibular shape. METHODS: From 2010 to 2021, 1241 patients diagnosed with square faces and received customized lower face contouring surgeries by the senior author were reviewed and analyzed to propose an "ABC" classification system for facilitating surgical planning. RESULTS: Among them, 998 (80.42%) received bilateral mandible reshaping, 155 (12.49%) underwent bilateral mandible reshaping combined with genioplasty, and 88 (7.09%) received asymmetric mandible reshaping. A modified classification system composed of three critical parameters (height, morphology/thickness, divergence) in three aesthetic zones (mandibular angle, mandibular body, chin) was proposed based on quantitative summarization of the CT database and the senior author's 12-year experience. The way to facilitate surgical planning with this classification was demonstrated. CONCLUSIONS: This modified classification system ushered a decision-making process that prioritized several critical measurements and proposed an operative planning form. Meanwhile, it can also be cooperated into the three-dimensional virtual surgical plan. LEVEL OF EVIDENCE IV: 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 http://www.springer.com/00266 .

Aesthetic Enhancement of the Gonial Angle and Inferior Mandibular Border in the Chinese Population.

BACKGROUND: The current absence of a standardized mandibular body osteotomy design poses challenges in surgical planning. Traditional approaches may not suit patients with wider anterior mandibles, potentially resulting in unsatisfactory outcomes. Addressing this issue requires a rational design that combines mandibular angle and body osteotomies for improved clinical practice. OBJECTIVES: In this retrospective cohort study we aimed to analyze mandibular computed tomography (CT) data with digital methods. The goal was to establish an integrated osteotomy design for both mandibular angle and body procedures and classify prevalent mandibular types in the Chinese Han population for surgical guidance. METHODS: Included were 89 patients who underwent mandibular angle osteotomy without genioplasty between 2016 and 2022 at Peking University Third Hospital. Mimics 21.0 software facilitated CT data reconstruction and osteotomy planning. Postoperative effects were assessed through imaging, complications, and surveys, leading to mandibular type classification. RESULTS: Mandibular angles were categorized by 3 types, based on osteotomy range. Type I involved mandibular body osteotomy only, type II mandibular angle osteotomy only, and type III both mandibular angle and body osteotomies. Distribution within the cohort was 2.25%, 8.99%, and 88.76% for types I, II, and III respectively. Patient satisfaction was high, with minor and major complications at 47.19% and 1.12% by Clavien-Dindo classification. CONCLUSIONS: Utilizing Mimics software, we established an integrated osteotomy design and categorized mandibular types. Findings offer valuable guidance for mandibular angle surgery and contribute to understanding of Asian mandibular morphology.

Expanded Transoral Microvascular Mandibular Reconstruction: A Scar-Free Approach.

PURPOSE: We present our experience with transoral segmental mandibulectomy, in conjunction with vascularized osseous mandibular reconstruction, utilizing an intraoral anastomosis and free of extraoral incisions. Virtual surgical planning and intraoperative navigation were used to help achieve this minimally invasive and scar-free approach. METHODS: A retrospective study was performed on 9 patients who underwent transoral segmental mandibulectomy followed by vascularized osseous reconstruction using an intraoral anastomosis between January 2018 and October 2018. The anastomotic recipient vessels were the facial artery and vein. The outcome variable was defined as the flap survival. Postoperative panoramic radiographs and computed tomography images were obtained for assessment of the neo-mandible. In addition, we performed a cadaver dissection to highlight relevant anatomic details of the facial artery and vein. RESULTS: Successful transoral segmental mandibulectomy was achieved in 9 patients, with an intraoral anastomosis successfully achieved in 8 patients. In one patient, an extraoral anastomosis was required because of challenging facial vein anatomy. Both recipient and donor sites healed uneventfully with a 100% successful rate of flap survival. In all cases, a well-positioned neo-mandible with good occlusion was demonstrated on postoperative imaging and examination. A symmetric facial appearance with no restrictions in mouth opening was also achieved in each case. In our cadaver dissection, we describe the anatomical course of the facial artery and vein. An average angle of 30° between these vessels is identified. CONCLUSIONS: Transoral segmental mandibulectomy combined with intraoral microvascular mandibular reconstruction is a surgically achievable technique with the benefit of being scar free.

Posterior Mandibular Segmental Split Osteotomy: A Novel Technique for Edentulous Space Reconstruction in Patients With Skeletal Class III Malocclusion.

ABSTRACT: This study presents an innovative surgery that successfully improved the facial profile and occlusal function of a patient with a skeletal Class III malocclusion and posterior hypodontia. The patient had chief complaints of missing teeth and a protrudedjaw. A novel 1-stage surgery referred to as posterior mandibular segmental split osteotomy combined with Le Fort i osteotomy and BSSRO was used because the patient wanted to save time and was worried about periodontal complications associated with other treatment methods. As a result, a satisfying facial profile and a Class I occlusion with a normal position of the posterior dentoalveolar segment of the mandible were achieved with no adverse effects. Thus, posterior mandibular segmental split osteotomy can be considered an effective treatment for skeletal Class III malocclusion with posterior hypodontia.

Application of Segmented Template in Three-Dimensionally Guided Mandibular Angle Osteotomy.

BACKGROUND: The procedure of mandibular angle osteotomy (MAO) via an intraoral approach is challenging and experience-dependent due to the limited field of view and inadequate operational space. Uncertainty about the osteotomy line and plane can lead to severe complications. A three-dimensional printed guidance template based on a computer-assisted preoperative simulation is a potential solution to this problem. The current study aims to retrospectively investigate the feasibility and accuracy of using a custom-made segmented template to guide the osteotomy plane during the procedure. METHODS: Sixty patients who had segmented template-guided MAO were included in the study. Preoperative simulation using the custom-designed template and postoperative computed tomography were collected and parameters, including mandibular angle, gonion distance, and the mandibular plane angle were measured. A paired t tests and intraclass correlation coefficients (ICCs) were used to evaluate the efficacy, accuracy, and symmetry of the results. All complications were reviewed. RESULTS: The patients had a significantly larger mandibular angle and narrower gonion distance postoperatively. Preoperative simulations and postoperative outcomes were compared; ICCs were larger than 95% indicating significant agreement. Bilateral postoperative comparisons of the mandible also demonstrated excellent agreement (ICC > 95%). Numbness in the chin area was the most frequent complication but all recovered by 3 months postoperatively. CONCLUSIONS: The custom-made template can guide the osteotomy plane during the MAO procedure and achieve favorable accuracy and symmetry. Direct contact of the saw with the guidance template not only facilitates control of the osteotomy line but also the oblique angle of the osteotomy plane. This methodology may be a feasible and effective tool for mandibular contouring.

Assessment of an Artificial Intelligence Mandibular Osteotomy Design System: A Retrospective Study.

BACKGROUND: In this study, an AI osteotomy software was developed to design the presurgical plan of mandibular angle osteotomy, which is followed by the comparison between the software-designed presurgical plan and the traditional manual presurgical plan, thus assessing the practicability of applying the AI osteotomy software in clinical practices. METHODS: (1) Develop an AI osteotomy software: design an algorithm based on convolutional neural networks capable of learning feature point and processing clustering segmentation; then, select 2296 cases of successful 3D mandibular angle osteotomy presurgical plans, followed by using those 2296 cases to train the deep learning algorithm; (2) compare the osteotomy presurgical plan of AI osteotomy software and that of manual: first step: randomly selecting 80 cases of typical female head 3D CTs, and designing those 80 cases by means of AI osteotomy software designing (group A) and manually designing (group B), respectively; second step: comparing several indexes of group A and those of group B, including the efficiency index (time from input original CT data to osteotomy presurgical plan output), the safety index (the minimum distance from the osteotomy plane to the mandibular canal), the symmetry indexes (bilateral difference of mandibular angle, mandibular ramus height and mandibular valgus angle) and aesthetic indexes (width ratio between middle and lower faces (M/L), mandibular angle and mandibular valgus angle). RESULTS: The efficiency index: the design time of group A is 1.768 ± 0.768 min and that of group B is 26.108 ± 1.137 min, with P = 0.000; the safety index: The minimum distances from the osteotomy plane to the mandibular canal are 3.908 ± 0.361mm and 3.651 ± 0.437mm, p = 0.117 in groups A and B, respectively; The symmetry indexes: Bilateral differences of mandibular angle are 1.824 ± 1.834° and 1.567 ± 1.059° in groups A and B, respectively, with P = 0.278; bilateral differences of mandibular ramus height are 2.083 ± 1.263 and 2.965 ± 1.433, respectively, with P = 0.119 in groups A and B; Aesthetic indexes: M/L in groups A and B is 1.364 ± 0.074 and 1.371 ± 0.067, respectively, with P = 0.793; mandibular angles in groups A and B are 127.724 ± 5.800° and 127.242 ± 5.545°, respectively, with P = 0.681; Valgus angles in groups A and B are 11.474 ± 5.380 and 9.743 ± 4.620, respectively, with P = 0.273. CONCLUSIONS: With high efficiency, as well as safety, symmetry and aesthetics equivalent to those of a manual design, the AI osteotomy software designing can be used as an alternative method for manual osteotomy designing. LEVEL OF EVIDENCE IV: 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.

Reduction Mandibuloplasty Along with Partial Masseter Muscle Resection: Masseter Muscle Response and Bone Regeneration.

OBJECTIVE: To compare the masseter muscle changes and bone regeneration between reduction mandibuloplasty along with partial masseter muscle resection and reduction mandibuloplasty alone. METHODS: Forty-seven patients who complained of prominent mandibular angle and hypertrophy masseter muscles (MMH) were divided into group 1 treated with reduction mandibuloplasty along with partial masseter muscle resection, and group 2 treated with reduction mandibuloplasty alone. Pre-5 days and long-term postoperative computed tomography data were collected, and the masseter muscle volume, hemi-mandible volume, and unilateral lower face width were measured. Patient satisfaction and complication were also evaluated. RESULTS: At long-term follow-up, group 1 showed a greater decrease in masseter volume (p < 0.001), and lower face width (p < 0.001), and less bone regeneration (p < 0.001) than group 2. Furthermore, patients in group 1 had higher satisfaction with the surgical outcome (p < 0.05). CONCLUSION: Reduction mandibuloplasty along with partial masseter muscle resection can achieve a slender frontal appearance and significantly decrease bone generation. For patients with MMH, reduction mandibuloplasty along with partial masseter muscle resection is an effective and predictable lower face reshaping surgery. LEVEL OF EVIDENCE IV: 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 Table of Contents or online Instructions to Authors www.springer.com/00266 .

Determining the optimal osteotomy distance with the fibula free flap in mandibular reconstruction.

OBJECTIVE: Fibula free tissue transfer is a common and reliable method for mandibular reconstruction. Functional outcomes from this procedure are dependent on the successful union of the osseous segments postoperatively. This study was conducted to define the maximum gap-size criteria for osseous union to occur at osteotomy sites in fibula free flap reconstruction of the mandible. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary care academic center. SUBJECTS AND METHODS: A retrospective chart review of computed tomography and medical records was conducted on patients who underwent fibula free flap surgery and had imaging of the mandible at <3 months and >6 months after surgery. Distances between osteotomies were measured and evaluated for interval healing. Secondary data included subject age, sex, smoking status, diabetes, number of osteotomies, complications, and adjuvant therapy. RESULTS: Thirty-eight osteotomy sites were analyzed from thirteen subjects and a total of 190 measurements were made. The mean gap size at the first scan that demonstrated union by the second scan interval was 1.31 mm and mean gap size demonstrating non-union was 2.55 mm (p < 0.01). Complication rate, number of osetotomies, adjuvant therapy, or medical co-morbidities did not significantly affect rates of union. CONCLUSIONS: In this study, osseous union was achieved with a mean osteotomy gap size of 1.31 mm. The data suggests that distances between ossesous segments >2 .55mm have a higher risk of non-union. We believe the information from this study will help augment current and future techniques in the field of mandible reconstruction.

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.

Clinical anatomy of the accessory mandibular foramen: application to mandibular ramus osteotomy.

PURPOSE: An accessory foramen around the mandibular foramen is called an accessory mandibular foramen (AMF). The clinical anatomy of the AMF has not been well described. The aim of this study was to reveal the clinical anatomy of the AMF for a better understanding of its implication during ramus surgeries. METHODS: Twenty-two sides fresh-frozen cadaveric heads with a mean age of 76.2 ± 14.4 years at death underwent dissection. The neurovascular bundles passing through the AMF were observed. Additionally, a hemi-face of a latex injected embalmed cadaver was dissected medially to laterally and the neurovascular bundles of the AMF investigated. RESULTS: A unilateral foramen, bilateral foramina, and absence of foramina were found in 45.4%, 18.2%, and 36.4%, respectively. The origin of the neurovascular bundle entering the AMF was a branch of the maxillary artery in 20% and a tributary of the inferior alveolar vein in 80%. In the latex embalmed cadaver, the AMF was found to contain a branch from the maxillary artery and a tributary of the maxillary vein. CONCLUSION: Given the practical meaning of the specific AMF located in the operative field of the ramus osteotomy, we suggest these be named "foramina for ramus osteotomy."

Surgical implications of the anatomic situation of the mandibular canal for mandibular osteotomies: a cone beam computed tomographic study.

PURPOSE: In bilateral sagittal split osteotomy (BSSO), the risk of lesion of the inferior alveolar nerve (IAN) is important. The aim of this study was to investigate the situation of the IAN in the area of the BSSO in preoperative 158 CBCT. METHODS: The situation of the mandibular canal (MC) has been studied in six coronal sections (one section each 4 mm) from the proximal root of the second mandibular molar. The height of the MC related to the height of the mandible, and the horizontal distance between the MC and the lateral cortical plate related to the mandibular width have been determined in each section. The cancellous bone width has been measured allowing to determine a cancellous bone ratio. RESULTS: The variability of the MC was high, depending mainly on the cancellous bone ratio which was higher when the IAN was deep. When a third molar was present, the MC was lower in the area of the third molar. CONCLUSIONS: To decrease the risk of injuring the IAN in BSSO, the evaluation of the cancellous bone ratio by a preoperative CBCT may be proposed to adapt the surgical technique to the anatomy.

Non-Autogenous Innovative Reconstruction Method Following Mandibulectomy.

BACKGROUND: Plexiform ameloblastoma is a locally aggressive odontogenic tumor, rare in the anterior mandible. The treatment of choice is resection with 1-3 cm free margins. In most of reported cases, the affected mandible is reconstructed by autogenic bone graft or osseocutaneous microvascular free flap in order to return function and esthetics. CASE DESCRIPTION: A 2 cm diameter exophytic ameloblastoma, located in the anterior mandible of a 50-year-old male was resected and reconstructed in a unique manner-allogenic bone block, recombinant human bone morphogenetic protein (rhBMP) and xenograft particles via transcutaneous submental approach. After bone maturation, dental implants were placed and restored by fixed prosthetics. PRACTICAL IMPLICATIONS: Mandible reconstruction modalities have a crucial influence on patient quality of life, function and esthetics. Allogenic bone block combined with rhBMP and xenograft particles can replace the traditional autogenous bone in certain circumstances. A submental transcutaneous "tent pole" approach can improve the success rate of the reconstruction procedure.