Distraction osteogenesis application in bone defect caused by osteomyelitis following mandibular fracture surgery: a case report and literature review.

BACKGROUND: Osteomyelitis secondary to mandibular fracture surgery is rare and complete surgical debridement of necrotic infected tissues is an optimal treatment for it. Subsequent reconstruction is required for bone defect caused by operation. Autogenous, allograft and synthetic bone graft substitutes have become widespread in bone defect treatment. Distraction osteogenesis (DO) was also applied in bone defect reconstruction, even it wasn't conventional therapy in jaw. CASE PRESENTATION: Here we report a case of a 40-year-old aged man who presented with chronic swelling and pain on the right mandibular masseteric region after mandibular angle and Le Fort II fracture surgery. In six weeks after surgery, CBCT images showed that the fracture ends hadn't heal and the fracture gap had widened significantly. The clinical diagnosis of the patient was right mandibular angle osteomyelitis. After controlling the symptoms of pain and infection with local rinses and systemic antibiotic therapy, the patient underwent segmental resection of the infected bone and DO reconstruction for bone defect simultaneously. Encouragingly, well bone healing and normal occlusion restoration was observed finally. CONCLUSIONS: DO could be a valuable alternative therapy to bone grafts for bone defect, even in the case of infection.

Assessment of the relationship between the three-dimensional precise location of the mandibular third molar and the volume ratio of the impacted mandibular third molar to the mandibular angle, and the patterns of mandibular angle fracture: A retrospective study.

This study aimed to evaluate the relationship between the precise three-dimensional location of the third molar (M3) and mandibular angle fracture (MAF) patterns and to assess the effect of the volume ratio occupied by M3 in the mandibular angle on fracture patterns. The location of M3 was assessed in 218 patients with MAF using computed tomography reconstruction. The bone volume of the mandibular angle and the bone volume occupied by M3 were measured to calculate the volume ratio of M3 to the mandibular angle (M3/MA). MAF patterns were categorized into simple fracture (Type I), displaced fracture (Type II), and comminuted fracture (Type III) based on fracture severity. The results showed that the location of M3 significantly influenced MAF patterns (vertical position: P = .001; horizontal position: P = .002; angulation: P = .027, respectively) and the volume ratio of M3/MA was significantly higher for Type III fracture than Types I and II (P < .001). Regression analysis showed that the horizontal position and angulation of M3 and the volume ratio of M3/MA were the main predictors for comminuted MAF. A larger volume ratio (odds ratio [OR], 1.201; 95% confidence interval [CI], 1.037-1.391; P < .014), Class III position (OR, 7.978; 95% CI, 1.275-49.910; P < .026), and horizontal angulation (OR, 7.212; 95% CI, 1.028-50.581; P < .047) of the M3 were more prone to comminuted MAF than simple fracture. Our findings indicate that the location of M3 significantly affects MAF patterns, and that M3 may weaken the mandibular angle by occupying more bone space, thereby increasing the risk of a comminuted fracture.

An experimental study of a novel external fixator based on universal joints for the rapid initial stabilization of mandibular comminuted fractures.

PURPOSE: Shaping and assembling contemporary external fixators rapidly for the severe mandibular fractures remains a challenge, especially in emergency circumstance. We designed a novel external fixator that incorporates universal joints to provide the stabilization for mandibular comminuted fractures. This study aims to confirm the efficacy of this novel external fixator through biomechanical tests in vitro and animal experiments. METHODS: In vitro biomechanical tests were conducted using 6 fresh canine with mandibular defect to simulate critical comminuted fractures. Three mandibles were stabilized by the novel external fixator and other mandibles were fixed by 2.5 mm reconstruction plates. All fixed mandibles were subjected to loads of 350 N on the anterior regions of teeth and 550 N on the first molar of the unaffected side. The stability was evaluated based on the maximum displacement and the slope of the load-displacement curve. In animal experiments, 9 beagles with comminuted mandibular fractures were divided into 3 groups, which were treated with the novel external fixation, reconstruction plate, and dental arch bar, respectively. The general observation, the changes in animals' weight, and the surgical duration were recorded and compared among 3 groups. The CT scans were performed at various intervals of 0 day (immediately after the surgery), 3 days, 7 days, 14 days, 21 days, and 28 days to analyze the displacement of feature points on the canine mandible and situation of fracture healing at 28 days. The statistical significance was assessed by the two-way analysis of variance test followed by the Bonferroni test, enabling multiple comparisons for all tests using GraphPad Prism10.1.0 (GraphPad Inc, USA). RESULTS: The outcomes of the biomechanical tests indicated that no statistically significant differences were found in terms of the maximum displacement (p = 0.496, 0.079) and the slope of load displacement curves (p = 0.374, 0.349) under 2 load modes between the external and internal fixation groups. The animal experiment data showed that there were minor displacements of feature points between the external and internal fixation groups without statistic difference, while the arch bar group demonstrated inferior stability. The CT analysis revealed that the best fracture healing happened in the internal fixation group, followed by the external fixation and arch baring at 28 days after fixation. The external fixation group had the shortest fixation duration (25.67 ± 3.79) min compared to internal fixation ((70.67 ± 4.51) min, p < 0.001) and arch baring ((42.00 ± 3.00) min, p = 0.046). CONCLUSION: The conclusion of this study highlighted the efficacy and reliability of this novel external fixator in managing mandibular fractures rapidly, offering a viable option for the initial stabilization of comminuted mandibular fractures in the setting of emergency rescue.

Titanium vs PEO Surface-Modified Magnesium Plate Fixation in a Mandible Bone Healing Model in Sheep.

Titanium plates are the current gold standard for fracture fixation of the mandible. Magnesium alloys such as WE43 are suitable biodegradable alternatives due to their high biocompatibility and elasticity modulus close to those of cortical bone. By surface modification, the reagibility of magnesium and thus hydrogen gas accumulation per time are further reduced, bringing plate fixation with magnesium closer to clinical application. This study aimed to compare bone healing in a monocortical mandibular fracture model in sheep with a human-standard size, magnesium-based, plasma electrolytic-oxidation (PEO) surface modified miniplate fixation system following 4 and 12 weeks. Bone healing was analyzed using micro-computed tomography and histological analysis with Movat's pentachrome and Giemsa staining. For evaluation of the tissue's osteogenic activity, polychrome fluorescent labeling was performed, and vascularization was analyzed using immunohistochemical staining for alpha-smooth muscle actin. Bone density and bone mineralization did not differ significantly between titanium and magnesium (BV/TV: T1: 8.74 ± 2.30%, M1: 6.83 ± 2.89%, p = 0.589 and T2: 71.99 ± 3.13%, M2: 68.58 ± 3.74%, p = 0.394; MinB: T1: 26.16 ± 9.21%, M1: 22.15 ± 7.99%, p = 0.818 and T2: 77.56 ± 3.61%, M2: 79.06 ± 4.46%, p = 0.699). After 12 weeks, minor differences were observed regarding bone microstructure, osteogenic activity, and vascularization. There was significance with regard to bone microstructure (TrTh: T2: 0.08 ± 0.01 mm, M2: 0.06 ± 0.01 mm; p = 0.041). Nevertheless, these differences did not interfere with bone healing. In this study, adequate bone healing was observed in both groups. Only after 12 weeks were some differences detected with larger trabecular spacing and more vessel density in magnesium vs titanium plates. However, a longer observational time with full resorption of the implants should be targeted in future investigations.

Risk factors for postoperative facial nerve injury in retromandibular-approach surgery: A retrospective study including CT measurements of maxillofacial bone structure.

The purpose of this retrospective study was to identify risks of postoperative facial nerve injury (FNI) in mandibular condylar fractures. A total of 59 consecutive cases of condyle fracture or plate removal with a retromandibular transparotid approach (RMTA) were divided into FNI and non-FNI groups that were evaluated for associations with age, sex, laterality, fracture type, height, weight, body mass index (BMI), and maxillofacial bone height and width diameters on computed tomography (CT). FNI occurred in 11 of 59 patients (18.64%), all of them female (p = 0.0011). Other statistically significant factors on univariate analysis for FNI included a short height (156.95 ± 8.16 cm vs. 164.29 ± 9.89 cm, p = 0.04), low weight (46.08 ± 8.03 kg vs. 58.94 ± 11.79 kg, p = 0.003), low BMI (18.64 ± 2.63 kg/m2 21.68 ± 3.02 kg/m2, p = 0.007), short condylion-anterior fracture distance (19.34 ± 3.15 mm vs. 22.26 ± 3.96 mm, p = 0.04) and short condylion-posterior fracture distance (20.12 ± 3.98 mm vs. 25.45 ± 5.02 mm, p = 0.009). Our retrospective study suggested that FNI with RMTA surgery occurs particularly in female patients and may occur more frequently in patients who are short, lean or have high condyle fractures.

Clinical results of two different three-dimensional plate types for the treatment of mandibular angle fractures: a retrospective analysis.

OBJECTIVES: The purpose of this study was to compare two different designs of three-dimensional osteosynthesis plates for their suitability in the treatment of mandibular angle fractures in terms of sufficient fracture healing and concomitant complications. MATERIALS AND METHODS: Retrospectively a total of 54 patients with 56 mandibular angle fractures were evaluated. Two different types of three-dimensional plates from the Medartis Trilock system were analyzed: (A) Square design plate (☐-plate) with a thickness of 1.0 mm, and (B) triangular-shaped 3D-plate (△-plate) with a thickness of 1.3 mm. Patient demographics, fracture mechanism and intraoperative details were recorded during an average follow-up period of 1 year. RESULTS: The utilization of △-plates was observed to entail a considerably lengthier surgical time in contrast to ☐-plate systems (P = 0.037). The application of △-plate showed a tendency of higher incidence of major complications than ☐-plate (P = 0.06), as evidenced by the occurrence of non-union in 2 out of 22 cases, resulting in higher surgical revision rate for △-plate (P = 0.027). CONCLUSION: Sufficient treatment of mandibular angle fractures is feasible by using 1.0 mm thick, square shaped three-dimensional plate systems. The use of thicker three-dimensional osteosynthesis plates seems to significantly increase the operating time and complication rates, whereby the geometry of the plate seems to have an influence. CLINICAL RELEVANCE: The plate design could have an impact on treatment outcomes of mandibular angle fractures. TRIAL REGISTRATION NUMBER: Not applicable.

Characteristics, Treatment, and Prognosis of Pediatric Symphyseal/Parasymphyseal-Condylar Fractures.

BACKGROUND: Pediatric condylar fractures combined with symphyseal or parasymphyseal fractures are common but challenging to manage. The authors present fracture characteristics, propose a treatment algorithm, and evaluate the treatment prognosis of pediatric symphyseal/parasymphyseal-condylar fractures. METHODS: A retrospective review was conducted on pediatric patients who underwent treatment for symphyseal/parasymphyseal-condylar fractures in a trauma center between January of 2006 and January of 2021. Demographic and fracture characteristics were recorded. Complications and functional evaluations, including maximum interincisal opening, Helkimo anamnestic index, and clinical dysfunction index, were assessed after at least 1 year of follow-up. RESULTS: After screening, 104 participants met the inclusion criteria. Among them, 50.96% received open reduction and internal fixation for symphyseal/parasymphyseal fractures and closed treatment for condylar fractures, 45.19% were treated by liquid diet and functional exercise, and the remaining 3.85% with severe malocclusion were treated with the assistance of orthodontic appliances. During follow-up, the average maximum interincisal opening of the patients increased from 17 ± 6.29 mm to 41.64 ± 6.33 mm. No subjective symptoms were observed in 86.54% of the patients and 79.81% showed no or mild clinical symptoms. Except for 1 patient who developed temporomandibular joint ankylosis, no other severe complication was reported. Postfracture remodeling of the nonfractured condyle was noted in 3 cases. CONCLUSIONS: Pediatric symphyseal/parasymphyseal-condylar fractures present unique biomechanical and anatomic challenges that require special consideration during management. In this study, satisfactory functional prognosis was achieved following implementation of the treatment algorithm. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Relationship between mandibular third molars and mandibular angle and condylar fractures.

BACKGROUND: Assess the correlation between the position of the third molar (M3) and fractures of the mandibular angle and condyle using panoramic radiographs to offer valuable data references for oral clinical research. MATERIAL AND METHODS: A retrospective cross-sectional study was undertaken, involving the collection of 409 cases of mandibular fracture in the Yanbian University Hospital. The case records and panoramic radiographs of mandibular angle fracture (78 cases) and condylar fracture (106 cases) were evaluated. RESULTS: In the comparative analysis between the mandibular angle fracture group and the condylar fracture group, statistical significance was observed in the variables of M3 existence (P = 0.002), eruption of M3 from the alveolar cavity (P = 0.003), P&G position classification (P = 0.001), deep impactions (Classes IC, IIC, IIIB, and IIIC) (P < 0.001), and the presence of impacted M3 in both groups (P < 0.001).Regarding M3 roots, the mandibular angle fracture group exhibited the highest prevalence of multiple roots at 75.4%, surpassing the 64.6% observed in the condylar fracture group. The prevalence of proximal angles in the mandibular angle group and the condyle group was the highest, accounting for 64.6% and 61.5%, respectively. The percentage of M3 in the two groups was 80% and 43.1%, respectively, with a significant difference (P < 0.001). CONCLUSIONS: Impacted mandibular third molars (M3) elevate the risk of mandibular angle fractures, while their absence or normal eruption reduces this risk and protects against condylar process fractures. The fracture risk is influenced by the M3's position: P&G Class II and Class B impactions, where M3s emerge partially from the alveolar bone, are significantly associated with mandibular angle fractures. In contrast, the absence of M3 or its placement in P&G Class I and Class A positions tends to correlate with a higher incidence of condylar process fractures.

Transoral endoscopic assisted reduction and internal fixation of mandibular condylar neck fractures with short condylar segment.

This study aimed to assess the reliability and safety of transoral endoscopic-assisted reduction internal fixation (TERIF) for treating short-segment condylar neck fractures (CNF), including hardware removal. Patients with displaced CNF and short condylar segments treated using TERIF were included in the study. Clinical evaluation covered dental occlusion, range of mouth opening, deviation during mouth opening, protrusion, laterotrusion, pain, and chewing. Radiological evaluation was used to assess fracture displacement, angulation, head dislocation, postoperative reduction, fixation stability, and bone healing. The same technique was used to treat 15 patients with 18 CNF and short condylar segments. Hardware removal was performed for nine fractures in eight patients after fracture healing using the same approach. All patients regained satisfactory, pain-free mouth opening with no deviation and complete bone healing. Computed tomographic images displayed adequate reduction and stable fixation during the follow-up period for all patients. No temporary or permanent facial nerve impairment occurred in any of the patients. TERIF is a reliable and safe treatment for CNF with short condylar segments, even in the presence of head dislocation, medial override, and malunited fractures; hardware can be safely removed after healing using the same approach.

Isolated fracture of the coronoid process following a molar extraction: A rare case report.

Isolated coronoid process fractures are uncommon, and iatrogenic isolated fractures are extremely rare. This case describes a displaced fracture of an isolated coronoid process thought to be due to excessive force applied by a dentist that had been overlooked and left untreated for about a month. The patient was a woman in her late 50's and she had undergone a molar extraction. Her dentist had confused her symptoms of trismus, pain, and facial oedema with the complex tooth extraction procedure. Following a cone-beam computed tomography (CBCT) scan we showed that the mandibular coronoid process on her right side had suffered a longitudinal fracture, and the fractured fragment had rotated upwards and inwards. Following successful surgical elimination of the fragmented coronoid process, the patient received targeted physiotherapy sessions that yielded excellent results. At the five-month follow-up, the ability of the patient to open her mouth had improved enormously, and her facial appearance almost recovered to its original state.

Evaluation of residual bone mass of the mandibular third molar and the risk of mandibular fracture.

BACKGROUND: A quantification of the residual bone mass of the mandible (B/A) was utilized in this study to examine the correlation between mandibular fracture and residual bone mass. To improve the clinical utilization rate and reduce the incidence of iatrogenic mandibular fractures, the B/A ratio calculation should be simplified. MATERIAL AND METHODS: Data were collected from the Yanbian University Hospital on 175 cases of mandibular fracture with third molar (M3), 67 normal cases without fractures and 20 cases of impacted teeth extraction. Twenty cases of iatrogenic mandibular fracture were collected, and the case records and panoramic radiographs of the patients were recorded. RESULTS: The average B/A ratio of mandibular angle fracture group was 0.61±0.10.The value of B/A was found to be statistically significant in terms of whether M3 emerged from alveolar bone (P = 0.001), location (horizontal P < 0.001, vertical P < 0.001), the degree of impaction (P < 0.001), the number of roots (P < 0.001), the difference in impaction (P < 0.001), and the fracture type (P = 0.002). The average B/A ratio of normal group was 0.62±0.10. In the statistical results of the B/A value of normal patients, M3 involving alveolar bone (P < 0.001), position classification (P < 0.05), degree of impaction (P < 0.001) and presence or absence of a root (P < 0.05) were statistically significant. The average B/A ratio of iatrogenic mandibular angle fracture group was 0.28±0.08. The average B/A ratio of the extraction group for impacted teeth was 0.62 ± 0.09. CONCLUSIONS: There is a high risk of mandibular angle fracture when the (B/A) value of the residual bone height (B) in the mandibular M3 area compared to the mandibular bone height (A) in the M3 area is less than 0.4.

Detection and classification of mandibular fractures in panoramic radiography using artificial intelligence.

OBJECTIVES: This study evaluated the performance of the YOLOv5 deep learning model in detecting different mandibular fracture types in panoramic images. METHODS: The dataset of panoramic radiographs with mandibular fractures was divided into training, validation, and testing sets, with 60%, 20%, and 20% of the images, respectively. An equal number of control images without fractures were also distributed among the datasets. The YOLOv5 algorithm was trained to detect six mandibular fracture types based on the anatomical location including symphysis, body, angle, ramus, condylar neck, and condylar head. Performance metrics of accuracy, precision, sensitivity (recall), specificity, dice coefficient (F1 score), and area under the curve (AUC) were calculated for each class. RESULTS: A total of 498 panoramic images containing 673 fractures were collected. The accuracy was highest in detecting body (96.21%) and symphysis (95.87%), and was lowest in angle (90.51%) fractures. The highest and lowest precision values were observed in detecting symphysis (95.45%) and condylar head (63.16%) fractures, respectively. The sensitivity was highest in the body (96.67%) fractures and was lowest in the condylar head (80.00%) and condylar neck (81.25%) fractures. The highest specificity was noted in symphysis (98.96%), body (96.08%), and ramus (96.04%) fractures, respectively. The dice coefficient and AUC were highest in detecting body fractures (0.921 and 0.942, respectively), and were lowest in detecting condylar head fractures (0.706 and 0.812, respectively). CONCLUSION: The trained algorithm achieved promising results in detecting most fracture types, particularly in body and symphysis regions indicating machine learning potential as a diagnostic aid for clinicians.

Management of Mandibular Condylar Sagittal Fracture Accompanied by Lateral Condylar Crest Defect.

BACKGROUND: The sagittal fracture of the mandibular condyle can be fixed with absorbable long screws. Absorbable long screws are generally inserted from the lateral crest of the condyle and are as close as possible to the medial pole of the condyle to obtain sufficient retention force. However, in clinical practice, patients with locally comminuted condylar fractures and partial defects in the lateral crest are often encountered. We validated the use of absorbable plates and long screws to fix mandibular condylar fractures with lateral crest defects, and postoperative follow-up showed good results. METHODS: The preoperative design indicated that if conventional long screws were used, more soft tissue need to be pulled downward to achieve the appropriate drilling angle. If an absorbable plate was used, the degree of downward pulling of soft tissue was smaller, which can better protect the parotid gland tissue and facial nerve. The surgery was performed according to the preoperative design, using an absorbable plate scheme. RESULTS AND DISCUSSION: Postoperative CT confirmed a stable anatomical reduction of condyle. Four-month follow-up showed that the patient's facial shape, occlusion, and mouth opening were all good. Follow-up CT showed good fracture healing. It is feasible to use absorbable plates and long absorbable screws to fix mandibular condylar sagittal fracture accompanied by lateral condylar crest defect.

Ultrasound-guided arthrocentesis for condylar head fracture: a technical report.

OBJECTIVES: Double puncture arthrocentesis (DPA) of the temporomandibular joint (TMD) is considered an effective preservative option for managing mandibular condylar head fractures. However, the procedure is commonly performed by a traditional "blind" method using anatomical characteristics. In the present study, an ultrasonography (US) device was applied for the treatment of a case with a fractured mandibular condyle. METHODS: A 79-year-old female was diagnosed right side condylar head fracture complaining pain of right TMD and reduced mouth opening range: inter-incisor distance of 20 mm. Since the fracture position was high and inoperable, the decision was made to perform DPA of the TMD. The US probe was positioned parallel and slightly oblique to the major axis of the mandibular ramus. Both the posterior and anterior insertions into the joint space were performed according to the axis mentioned above, which enabled the operator to visualize the entirety of the needle. RESULTS: The device offered safety and ensured accuracy by providing real-time visual aid to the surgeon. The procedure provided an early increase in the inter-incisor distance (31 mm) and pain relief. CONCLUSIONS: Hence, for the preservative treatment of mandibular condylar head fractures, based on the present study, we recommend US-guided arthrocentesis as a safe, feasible, and effective therapeutic option instead of the conventional "blind" method.

Postoperative Intermaxillary Elastic Traction Contributes to the Stability of Absorbable Plates Fixation for Bilateral Mandibular Fracture.

The use of absorbable plates can be challenging for mandibular fractures involving bilateral dentition. Chewing and mouth opening movements may cause loosening or breakage of absorbable materials, leading to displacement of bone segments and resulting in malocclusion. The use of absorbable materials for bilateral mandibular fracture surgery itself raises concerns for surgeons. Timely intermaxillary elastic traction is essential for these patients after surgery to maintain correct occlusion. The surgical approaches were performed with intraoral mandibular sulcus incisions. During the surgery, intermaxillary fixation screws were implanted and steel wires were used for intermaxillary ligation and fixation to restore the occlusal. After the fractured segments were sequentially reduced, they were fixed with inion 2.0 absorbable plates. The patient underwent intermaxillary elastic traction for 1 week. Elastic mask was used to assist in stabilizing the position of the jawbone and maintaining occlusion. After discharge, the patient continued traction at home for 3 weeks before removing the intermaxillary fixation screws. The patient recovered well after surgery without any complications. The postoperative occlusal relationship is good. Postoperative CT showed good reduction of the fractured segments. For the case reported in this article, elastic traction was promptly implemented after surgery. We emphasize that restoring occlusion is always the treatment goal for jawbone fractures. We believe that keeping the intermaxillary fixation screws for a month is a wise choice to be prepared for unexpected needs.

Bone quality assessment in patients with healing mandibular fracture sites: a computed tomography investigation.

The objective of this retrospective study was to assess the bone quality of healing mandibular fracture sites by measuring the Hounsfield units (HU) on computed tomographic (CT) images obtained presurgery and postsurgery in patients treated with rigid internal fixation (RIF). The HU values of healing fracture sites were compared to those of corresponding nonfractured (control) sites on the opposing side and cervical vertebrae sites in the same patients. In total, 31 patients with 45 mandibular fractures treated with RIF underwent presurgical and postsurgical CT examinations. The scans performed after surgery (1, 3, 6, 12, or 18 months) were taken only when there was a need for radiographic evaluation due to a complaint of discomfort from the patient or when the surgeon needed to verify the postsurgical outcome, and each patient underwent only a single postsurgical CT. At the presurgical CT examination, the HU values were lower in the fracture sites than in the control sites. At 3 months postsurgery, the HU values in the fracture sites had increased as the mandibular bone healed. At 6 months postsurgery, the HU values in the fracture sites were higher than those of the control sites. At 12 and 18 months postsurgery, the HU values of both sites were similar. The HU values of the cervical vertebrae remained constant with time. These results suggest that, in patients who have been treated with RIF for mandibular bone fracture, HU values measured by CT vary across time, expressing the physiologic bone healing process.

A single-centre retrospective 10-year experience of the rhombic 3D condylar fracture plate for open reduction and internal fixation of condylar neck and base fractures.

Fractures of the mandibular condyle account for a significant proportion of mandibular fractures. The specific functional loads require particular specifications for the implant design used for open reduction and internal fixation of such fractures. The clinical and radiographic outcomes in patients treated using a single rhombic 3D condylar fracture plate for open reduction and internal fixation at a single institution, and who fulfilled the inclusion and exclusion criteria, are presented. The primary outcome variables were: occlusion, maximum interincisal distance and mandibular excursion at 1, 3, and 6 months postoperatively, and radiographic measurements for mandibular height and gonion angle. In total, 263 patients were included, of whom 173 (65.8%) were male and 90 (34.2%) female. The mean age was 40.4 ± 18.9 years. There was satisfactory occlusion in 98.9% of patients at the 6-month follow-up, and a significant improvement in all parameters for mandibular excursion (p < 0.001), with a reduced ramus height and an increase in the gonion angle on the fractured side. Excellent clinical and radiographic results were achieved using the rhombic-shaped implant, deeming it appropriate for the osteosynthesis of mandibular condyle fractures.

M3YOLOv5: Feature enhanced YOLOv5 model for mandibular fracture detection.

BACKGROUND: It is very important to detect mandibular fracture region. However, the size of mandibular fracture region is different due to different anatomical positions, different sites and different degrees of force. It is difficult to locate and recognize fracture region accurately. METHODS: To solve these problems, M3YOLOv5 model is proposed in this paper. Three feature enhancement strategies are designed, which improve the ability of model to locate and recognize mandibular fracture region. Firstly, Global-Local Feature Extraction Module (GLFEM) is designed. By effectively combining Convolutional Neural Network (CNN) and Transformer, the problem of insufficient global information extraction ability of CNN is complemented, and the positioning ability of the model to the fracture region is improved. Secondly, in order to improve the interaction ability of context information, Deep-Shallow Feature Interaction Module (DSFIM) is designed. In this module, the spatial information in the shallow feature layer is embedded to the deep feature layer by the spatial attention mechanism, and the semantic information in the deep feature layer is embedded to the shallow feature layer by the channel attention mechanism. The fracture region recognition ability of the model is improved. Finally, Multi-scale Multi receptive-field Feature Mixing Module (MMFMM) is designed. Deep separate convolution chains are used in this modal, which is composed by multiple layers of different scales and different dilation coefficients. This method provides richer receptive field for the model, and the ability to detect fracture region of different scales is improved. RESULTS: The precision rate, mAP value, recall rate and F1 value of M3YOLOv5 model on mandibular fracture CT data set are 97.18%, 96.86%, 94.42% and 95.58% respectively. The experimental results show that there is better performance about M3YOLOv5 model than the mainstream detection models. CONCLUSION: The M3YOLOv5 model can effectively recognize and locate the mandibular fracture region, which is of great significance for doctors' clinical diagnosis.