Mandibular Angle Osteotomy Research Articles

Automated Preoperative Planning Algorithm for Mandibular Angle Osteotomy Based on Anatomical Landmarks Detection: A Retrospective Study.

The aim of the study was to develop and evaluate an automated preoperative planning algorithm based on anatomical landmark point recognition for enhancing the efficiency and intelligence of preoperative planning for mandibular angle osteotomy. A retrospective cohort of 34 patients underwent preoperative planning with this algorithm. The present algorithm was developed using a method based on anatomical marker point recognition. The efficiency, symmetry, and safety of the automated preoperative planning and esthetics were statistically analyzed by paired t test and χ2 test. The results showed that the automated planning algorithm was able to achieve a great improvement in preoperative planning efficiency as well as safety and symmetry. A prospective case report of 2 patients is then reported, illustrating the safety and esthetics of the algorithm with 1-year postoperative follow-up and postoperative esthetic scores. This algorithm can help to improve the efficiency of preoperative planning for surgeons while ensuring safety and esthetics and can be further applied to other craniomaxillofacial personalized design surgeries in the preoperative design in the future.

Morphological Changes of the Temporomandibular Joint and Masseter Muscle After Mandibular Angle Osteotomy.

Mandibular angle osteotomy with outer cortex grinding is an effective cosmetic procedure for correcting square faces. However, morphological changes in the mandible may also cause temporomandibular joint (TMJ) disorders. This retrospective study aimed to investigate the morphological stabilization of the TMJ and changes in masseter muscle thickness after mandibular angle osteotomy to evaluate the safety of the procedure. Data from patients who underwent mandibular angle osteotomy with outer cortex grinding between January 2016 and January 2019 were retrospectively reviewed. Preoperative and long-term follow-up (~1 y) computed tomography data were collected from these patients, and morphological changes in the TMJ and masseter muscle were analyzed. The results from the computed tomography data showed that the condylar length and condylar height were significantly reduced 1 year after the operation ( P < 0.05). In addition, the morphology of the TMJ was stable, and the distance between the mandibular condyle and the glenoid fossa did not change significantly. No significant difference was observed in masseter muscle thickness before and after the operation. After mandibular angle osteotomy with outer cortex grinding, the length and height of the mandibular condyle were functionally restored without any disorders of the TMJ. Moreover, the masseter muscle exhibited stable function. In conclusion, the procedure is safe for occlusal function and suitable for popularization.

Inferior Alveolar Nerve Repositioning With the Computer-Aided Design in Hemimandibular Hyperplasia.

A 34-year-old man presented with facial asymmetry and was diagnosed with left-sided hemimandibular hyperplasia. Orthognathic surgery and mandibular angle osteotomy combined with inferior alveolar nerve repositioning were performed with computer-aided design. The facial asymmetry was successfully corrected with acceptable cosmetic results. Inferior alveolar nerve repositioning provided sufficient space for the osteotomy of the affected side with the abnormal mandibular canal. Inferior alveolar nerve repositioning with computer-aided design can be used as an effective and reliable technique for hemimandibular hyperplasia.

Correcting facial asymmetry through guided plate assisted mandibular angle osteotomy.

Asian women prefer a smooth and narrowed mandibular appearance. The purpose of the retrospective cohort study is to evaluate guide plate-assisted mandibular angle ostectomy (MAO) in improving mandibular symmetry for Asian female patients with mandibular angle hypertrophy (MAH) with normal occlusal relationship. We retrospectively examined 11 patients with asymmetry MAH with normal occlusal relationship who received MAO at Shanghai Ninth People's Hospital between September, 2020, and January, 2022. Preoperative plans were designed based on CT data and executed using metal guide plate during the operation. Preoperative and one-week postoperative CT scans were used to assess measurements including Height_Go, Divergence_Go, ∠ZyZy-GoGo, and osteotomy volume, to evaluate symmetry. For precision, compare the postoperative CT with the preoperative design, assessing osteotomy distance, angle, and volume error. Patient satisfacation was evaluated with Likert Scale in 6-month follow-up. Secondary lipofilling procedures were given as appropriate. Statistical analysis was performed using paired t-tests in SPSS. The mean age of the 11 patients was 28.5 years (range 23-34 years). 2 of these underwent lipofilling procedures. No complications were observed during the following-up. Postoperative results were not statistically different from the design, demonstrating a precision of within 2 mm. Height_Go disparity within 5 mm get corrected notably, reducing asymmetry from 15.09% preoperatively to 2.74% postoperatively. Patients satisfaction was rated at 4.5 out of 5 in 6 month follow-up. Guide plate-assisted mandibular angle osteotomies achieve effective and precise surgery. This approach demonstrates a safe option for correction for mandibular asymmetry, achieving patient satisfaction.

An innovative mixed reality approach for maxillofacial osteotomies and repositioning

Craniomaxillofacial surgeries are performed using custom-made physical cutting guides and resin dental splints that present several drawbacks (e.g. time and cost required for their design and production). The literature commonly provides augmented/mixed reality (AR/MR) solutions for assisting maxillofacial osteotomies and repositioning without any interactive guide. This work proposes a new MR application, useful for osteotomy and repositioning, providing interactive, fast, and intuitive feedback to the surgeon, who is then supported in performing the bone fragment resection and replacement frame by frame. The proposed application speeds up the surgery and reduces under/overshooting errors. Moreover, the idea of integrating osteotomy and repositioning assistance in the same MR application is rarely found in the literature. It is an entirely novel approach to craniomaxillofacial surgery. The MR application has been designed with a three-button menu. The “App Start” calibrates the app, the “Osteotomy Mode” visualises the holograms of the cutting lines and drilling points, and the “Repositioning Mode” visualises the step-by-step real-time feedback to precisely support the surgeon placing the osteotomised bone fragment towards the final pre-planned position. The MR app has been developed in Unity and deployed on Microsoft HoloLens V2. A laboratory test bench was realised to validate the accuracy of the proposed MR-based approach. The validation protocol consists of two tasks to test the osteotomy and repositioning modes using a 3D-printed skull phantom. For osteotomy, the accuracy is 0.89 mm (genioplasty), 1.24 mm (maxillary osteotomy), 1.33 mm (orthognathic surgery), and 2.89 mm (mandibular angle osteotomy). For repositioning, the accuracy is 0.6 mm (anteroposterior deviation), 0.7 mm (mediolateral deviation), and 0.6° (angular deviation).

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

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. 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. 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. 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. 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.

The Feasibility of Electromagnetic Navigation Technique to Achieve Preoperative Plan in Mandibular Angle Osteotomy

In contrast to the most commonly used optical navigation system, electromagnetic navigation has huge potential in operations with a narrow field. The purpose of this experiment was to test and confirm whether the electromagnetic navigation method the authors developed for mandibular angle osteotomy (MAO) met clinical requirements. Using a dental splint that could be repeatedly mounted on teeth, registration between surgical plan and actual field was performed automatically. Navigation of MAO was first performed on 10 mandibular models. The position precision measured using a coordinate measuring machine was 1.30±0.61 mm. Then, a navigation experiment was performed on 4 patients. Accuracy in actual operation measured by the NDI pointing sensor was 1.89±0.76 mm. Our noninvasive automatic registration process reduced the surgical exposure time and eliminated the bias of the manual selection of registration points. This preliminary study confirmed the feasibility of the electromagnetic navigation technique in terms of both applicability and accuracy in MAO surgery.

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

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. 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. 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. 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.

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. (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). 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. 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. 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.

Masticatory muscle tendon-aponeurosis hyperplasia: clinical presentation and management

Introduction: Masseter muscle enlargement accompanied by hypertrophy of Mandibular angle can significantly affect the appearance and quality of life. The treatment methods can be varied, and, in the present study, osteotomy of Mandibular angle and treatment of Masseter muscle with Botulinum toxin was carried out. Observation: In this case study, a 19-year-old female patient was admitted with inadequate mouth opening for three years. Clinical examination and Cone-Beam Computed Tomography scan revealed bilateral well-developed Masseter muscles and hypertrophy of mandibular angle on both sides. Osteotomy of mandibular angle was performed. Additionally, 25 units of Botulinum toxin were administered. This improved the aesthetic appearance and increased the mouth opening from 21 mm to 38 mm in one year after surgery. Conclusion: Oral and maxillofacial surgeons should consider Masticatory muscle tendon-aponeurosis hyperplasia as a differential diagnosis when the patient's chief complaint is inadequate mouth-opening with a square mandible. Osteotomy of mandibular angle in conjunction with, Botulinum toxin is efficient in cases of Masseter muscle hypertrophy and an enlargement of the Mandibular angle.

A simple method with a sterilized surgical glove for removal of stripped screw

In oral and maxillofacial surgery such as orthognathic surgery and open treatment of maxillofacial fracture, plate fixation is commonly performed. Although the removal of titanium miniplates is controversial, the plates are removed routinely or symptomatically. By excessive torque during the screw removal, stripping or breaking of screw heads may occur. Although miniplates and screws are used with angled screwdrivers for osteosynthesis in bilateral sagittal split osteotomy (BSSO) or open treatment of mandibular angle or subcondylar fracture, the removal of a damaged screw, especially with the angled screwdriver, is very difficult. Therefore, we report a simple method with a sterilized surgical glove for removal of the stripped screw.

Relationship Between Masticatory Muscle Size and Bone Regeneration After Mandibular Angle Osteotomy.

Mandibular angle osteotomy with outer cortex grinding has become the preferred cosmetic procedure for correcting square faces. After surgery, bone hyperplasia at the mandibular angle affects the operation result. This study evaluated the effect of the masticatory muscles on bone repair. From January 2016 to January 2019, patients who underwent mandibular angle osteotomy with outer cortex grinding were retrospectively reviewed. Computed tomography data of these patients were collected, and the bone volume of the mandibular angle changes and its correlation with masticatory muscle morphology were analyzed. Computed tomography data measurement results showed that a large amount of bone in the mandibular angle area was removed by the operation; however, the long-term follow-up results showed that there was bone hyperplasia in the mandibular angle areas. Compared with the immediate postoperative bone volume, the difference was statistically significant (P < 0.01). The thickness and cross-sectional area of the masseter muscle were significantly related to bone regeneration (P < 0.01). This study suggests that mandibular angle osteotomy with outer cortex grinding could ablate the symptoms of a prominent mandibular angle; however, muscle-related bone hyperplasia in the mandibular angle area after surgery was a non-negligible event, which may significantly compromise surgical outcomes.

Robot-assisted mandibular angle osteotomy using electromagnetic navigation.

To explore the potential of electromagnetic (EM) navigation technology in the field of robot-assisted surgery, we set up a maxillofacial surgical robotic system (MSRS) guided by an EM navigation tool. Mandibular angle osteotomy was used to analyze the feasibility in confined surgical areas. Model and animal experiments were implemented to validate the system precision. Before the experiment, a customized dental splint was made and then fixed with a standard navigation part. An accurate 3D surgical plan was designed based on the preoperative CT scan. During the experiment, the splint was rigidly mounted on teeth for navigation registration, so the robot could position a specially designed template to guide the accurate osteotomy according to the preoperative plan. For the model experiment, a Coordinate Measuring Machine was used to measure the template's position and angle. For the animal experiment, surgeons completed the surgery by moving a saw along the template, while a postoperative CT scan was carried out to calculate the precision. All procedures were successfully completed, with no complications in any of the experimental animals. In the model experiment, the accuracy of the navigation position and angle was 0.44±0.19 mm and 3.5°±2.1°, respectively. In the animal experiment, the lateral osteotomy line error was 0.83±0.62 mm, the interior error was 1.06±1.03 mm, and the angle between the actual cutting plane and preoperative planning plane was 5.9°±4.7°. Robot-assisted surgery with EM navigation resulted feasible in the real operating environment. Moreover, this system's precision could meet clinical needs, while the proposed procedure was safe and easy on animals. Consequently, this approach has the potential to be applied to clinical craniomaxillofacial practice in the near future.

Simultaneous Surgery for Contouring the Prominent Zygoma and Mandibular Angles With Facelift in Middle-Aged Patients.

As the pursuit of higher self-attractiveness grows, an increasing number of middle-aged people are unsatisfied with their facial contour and required osteotomy. However, for these patients, performing osteotomy only would accelerate the aging process. Herein, the authors put forward simultaneous surgery for contouring the prominent zygoma and mandible with facelift for elderly patients. Patients were divided into 3 groups: group A with prominent mandible, group B with protruding zygoma, and group C with prominent mandible and zygoma. By implementing intraoral incision, outer cortex grinding, mandibular angle curved osteotomy, and reduction malarplasty were performed. Through facelift incision, the zygomatic arch was reduced and facelift was conducted. Patients were followed up for at least 12 months and were asked to evaluate their experience. From March 2009 to January 2018, a total of 55 patients received the surgery: 17 patients received mandibular angle osteotomy and facelift, 22 received malarplasty and facelift, and 16 underwent mandible and zygoma contouring and facelift. The recovery process was uneventful, with only 2 patients in group A and 1 patient in group C who suffered from a hematoma, which relieved without surgical intervene. The postoperative images showed smoother facial contours. Patients were satisfied with surgical outcomes. Significant improvements were seen comparing pre- and postoperative photos. Conducting osteotomy and rhytidectomy concurrently results in smooth facial contour and youthful appearance which improves patients' self-image and contributes to high patients' satisfaction. With a low complication rate and no long-term complication, the surgery is safe to perform. Level IV, the case study.

WITHDRAWN: The application of three-dimensional reconstruction of mandibular neural tube in osteotomy of mandibular angle

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The influence of different eating ways on the postoperative rehabilitation of female patients with the operation of mandibular angle osteotomy of inside oral cavity

Objective Researching the influence on patients with different eating ways after the operation of mandibular angle osteotomy of inside oral cavity. Method By using the method of convenience sampling, 50 patients were chosen who had operation of mandibular angle osteotomy of inside oral cavity in orthopedic surgery department of our hospital from January 2017 to December 2017 and the number was arranged according to the order of hospitalization. Patients with singular member were divided into the month feeding group (liquid diet were fed with the injection syringe which linked leather hose of 4-5cm after 6 hours awakening after general anesthesia in operation); patients with even number were divided into the nasal feeding group (stomach tube was put in the operation and nasal feeding was provided after 6 hours awakening after general anesthesia in operation and 5 hours after the operation). In every group, there were 25 patients. Observation scale which was made by themselves was used to evaluate the patients in the two groups and comparison for difference was made in the two groups, including weight change, wound drainage amount, oral wound secretion, the aspects of choke and cough, and the comfortable sensation of eating. Results For weight, in nasal feeding group, (2.19±0.48) kg were reduced and in month feeding group, (5.78±0.58) kg were reduced; the difference had the statistical significance (t=23.870, P 0.05). Conclusion The nasal feeding way can improve recovery level for patients after the operation of mandibular angle osteotomy of inside oral cavity and it is worthy of promotion in clinic application. Key words: Eating way; Inside oral cavity way; Mandibular angle osteotomy; Postoperative rehabilitation

Parapharyngeal Hemangiopericytoma: the Role for Mandibular Proximal Segment Replantation-Review of Literature.

Pharyngeal hemangiopericytoma is a rare tumor .Surgical access to space has been selected based on the location of the tumor in this space, size, and type of pathology. Hemangiopericytoma requires extracapsular dissection. Hemorrhagic nature and tight attachment to adjacent tissues are the other reasons for choosing the surgical approach with the best access. The patient was a 55-year-old female with left-sided facial swelling and dumbbell-shaped lesion involving buccal and lateral pharyngeal space. Brisk hemorrhage happened during biopsy. Submandibular incision, osteotomy of mandibular angle, and temporary proximal segment removal were done. Extracapsular dissection of the lesion performed under direct vision. Proximal segment was returned to the original location and internally fixed with miniplate. Postoperative course was without complication. Mandibular proximal segment replantation technique should be used to treat parapharyngeal tumors with a hemorrhagic tendency.

Application of three-dimensional printing technology in osteotomy for chin width and prominent mandibular angle

Objective To explore the applied value of computer-aided design and three-dimensional printing technology in osteotomy for chin width and prominent mandibular angle. Methods Sixteen patients with chin width and prominent mandibular angle were admitted to the Plastic Surgery Ward of the Second Affiliated Hospital of Zhengzhou University. All patients underwent preoperative computer-aided design, three-dimensional reconstruction of head and face, reconstruction of mandibular nerve canal, intelligent osteotomy line design of chin and mandible, simulation of chin and mandibular angle osteotomy, 3-D printing of surgical template to complete osteotomy, and internal fixation of chin osteotomy plate. The mandibular angle (Co-Go-Me), mandibular ramus height (Co-Go), mandibular body length (Go-Me), subfacial width (Go-Go’), chin nodule width (Ge-Ge’) and face height (N-Me) were measured preoperation, before surgical simulation and postoperation. Co-Go-Me, Co-Go/Go-Me, Go-Go’/N-Me and Ge-Ge’/N-Me were compared and analyzed in preoperation, before surgical simulation and postoperation. Results All the patients were satisfied with their facial shape. The mandible was almost symmetrical after operation. No complications such as nerve injury and infection occurred after operation, which fully met the preoperative design requirements. The mandibular angles in the left and right sides of patients before operation were significantly less than those after operation (t=2.890, 2.886, P 0.05). The average mandibular angles after operation were (123.9±3.0)°. Co-Go/Go-Me in the left and right sides of patients before operation was significantly higher than that after operation (t=3.607, 2.860, P 0.05). The ratio of the length of the left and right mandibular body to the height of the ascending ramus was close to 2: 1. Preoperative Go-Go’/N-Me was significantly higher than that post-operation (t=3.102, P 0.05). Preoperative Ge-Ge’/N-Me was significantly higher than that post-operation (t=3.010, P 0.05) . Conclusion The application of computer-aided design and three-dimensional printing technology in osteotomy for large chin and hypertrophic mandibular angle can significantly improve the accuracy of operation, reduce the difficulty of operation, improve the cosmetic effect, and reduce the occurrence of complications such as infection and injury of important nerves and blood vessels. Key words: Chin width; Prominent mandibular angle; Computer-aided design; Surgical template; Three-dimensional printing technology

Application of computer-assisted navigation in mandibular angle osteotomy

ObjectiveTo compare the effectiveness, accuracy, and surgical safety of a navigation technique with those of a traditional technique for intraoperative mandibular angle osteotomy.MethodsForty-three postsurgical patients with mandibular angle hypertrophy who were admitted to our Department from June 2014 to June 2017 were retrospectively reviewed. Of these patients, 23 underwent mandibular angle osteotomy using computer-assisted navigation (navigation group), and 20 underwent osteotomy using a traditional technique (traditional group). Postoperative computed tomography images were analyzed by three-dimensional software. Each patient’s facial proportion indices were measured using Mimics 19.0 software, and statistical comparisons and analyses were performed preoperatively and postoperatively.ResultsThe postoperative facial contour morphology and facial proportion were improved in both groups; the navigation group showed greater improvement. The difference between the predicted and postoperative values was smaller in the navigation group than traditional group. The postoperative shape of the mandibular angle sample was similar to the preoperative predicted shape in the navigation group. No complications occurred in the navigation group, but paresthesia occurred in 17% of patients in the traditional group.ConclusionsMandibular angle osteotomy aided with computer-assisted navigation is more effective, accurate, and safe than the traditional technique and represents a promising clinical approach.

Clinical effects of platelet rich fibrin in prevention of bleeding and swelling after mandibular angle reduction

Objective To observe the clinical effect of platelet- rich fibrin (PRF) on prevention of postoperative hemorrhage and facial traumatic swelling in patients with mandibular angle osteotomy. Methods Twenty-five patients with mandibular angle hypertrophy were included in this study from January 2014 to November 2015. Split face comparative study was carried out to use the left and right sides as the experimental side and the control side, respectively. The PRF in the experimental side was placed in the mandibular osteotomy, while the control side was placed in platelet- poor plasma (PPP). After operation, the drainage volume and facial swelling degree were measured. Results The drainage volume of the experimental group (PRF group) was (20.35±7.40) ml, the control group (PPP group) was (43.23±11.96) ml, and the difference was statistically significant (P<0.05). There was no such case without swelling in postoperative third day. The facial swelling score on the experimental side was (1.19±0.40), the control side was (2.62±0.64), and two groups of postoperative facial swelling scores were significantly different (P<0.05). Conclusions The PRF can reduce postoperative bleeding and facial swelling after mandibular angle osteotomy. Key words: Mandibular angle reduction; Platelet- rich fibrin; Postoperative hemorrhage; Facial traumatic swelling