Maxillofacial Bone Research Articles

METTL3 Promotes Osteo/Odontogenic Differentiation of Stem Cells by Inhibiting miR-196b-5p Maturation.

Mesenchymal stem cells (MSCs) have been considered a potential method for the regeneration of tooth and maxillofacial bone defects based on the multidirectional differentiation characteristics of MSCs. miRNAs have been found to play a key role in the differentiation of MSCs. However, its effectiveness still needs to be improved, and its internal mechanism is still unclear. In the present study, our data discovered that the knockdown of miR-196b-5p promoted alkaline phosphatase (ALP) activity assay, mineralization in vitro, and expressions of osteo/odontogenic differentiation markers DSPP and OCN and enhanced in vivo osteo/odontogenic differentiation of stem cells of the apical papilla (SCAPs). Mechanistically, the results indicated that METTL3-dependent N6-methyladenosine (m6A) methylation inhibited miR-196b-5p maturation by the microprocessor protein DGCR8. Moreover, miR-196b-5p indirectly negatively regulates METTL3 in SCAPs. Then, METTL3 was found to strengthen the ALP activity assay, mineralization, and expressions of osteo/dentinogenic differentiation markers. Taken together, our findings highlight the critical roles of the METTL3-miR-196b-5p signaling axis in an m6A-dependent manner in osteo/odontogenic differentiation of SCAPs, identifying some potential targets for tooth and maxillofacial bone defects.

RECURRENT ODONTOGENIC FIBROMYXOMA OF SUBMANDIBULAR AND LEFT TEMPORAL REGION: A CASE REPORT

Odontogenic myxofibroma (OM) is a benign odontogenic tumour of maxillofacial bone with locally aggressive behaviour. It is thought to arise from the odontogenic ectomesenchyme of dental pulp or periodontal ligament. Odontogenic myxofibroma typically presents as painless slow growing tumour with high recurrence rates ranges from 10% to 45%. A case of recurrent odontogenic myxofibroma of submandibular, left preauricular and left temporal region presented in this case report. An 11-year-old Malay girl complaint of a painless, gradually progressive firm swelling on the lower left side of the jaw for 6 months duration. On clinical examination revealed firm swelling from the left angle of the mandible to the left parasymphysis area. A dental panoramic radiograph and computed tomography (CT) scan of the head and neck showed expansile lesion at left posterior mandible causing thinning and erosion of the mandibular cortex, multiloculated with tooth germ of 38 within and displaced inferiorly. Histopathological examination revealed stellate to spindle shape cells dispersed in a myxoid background. A final diagnosis of odontogenic myxofibroma has been made. Hence, left segmental mandibulectomy with condyle disarticulation was done via a submandibular approach. Unfortunately, a year later she had recurrence at bilateral submandibular region extending to left preauricular and left temporal region associated with pain and unable to close her mouth. Multiple surgery was carried out beginning with removal of the tumour at the bilateral submandibular region followed by removal of tumour at left temple. The operations were uneventful. However, tumour excision in the left preauricular region is yet to be performed pending magnetic resonance imaging (MRI) investigation to evaluate the soft tissue extension prior to surgical planning.

Clinical Characterization of Oral and Maxillofacial Tumors and Tumor-Like Lesions in Children and Adolescents.

To investigate the clinical characteristics of oral and maxillofacial tumors in children and adolescents. This is a retrospective study of patients who had oral and maxillofacial tumors under the age of 18 years and were treated at the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology from January 1990 to July 2021 (31y). Their general conditions, pathological diagnosis, gender, age, and anatomical location were counted to analyze their morbidity and composition characteristics. This study contained 5405 cases, including 2903 male patients and 2502 female patients, with a median age of 9 years. Peak incidence was observed in the 14 to 18 years age group. The mandible (22.15%), maxilla (11.75%), and tongue (9.25%) were the most common sites of incidence. Malignant and intermediate type tumors accounted for 13.04%, benign tumors and tumor-like lesions for 55.67%, most often occurs in the maxillofacial bone, of which fibro-osseous lesions constitute an important part. Cysts accounted for 31.29%. Among the tumors occurring in the jaws, the most common malignant type was sarcoma, and ameloblastoma was the most common benign tumor. Malignant jaw tumors were mostly treated by resection, 10.64% by fibular flap reconstruction. While benign jaw tumors and tumor-like lesions were mostly treated by resection or curettage. The distribution of anatomical location and pathological types of oral and maxillofacial tumors in children has certain characteristics, so that the selection of their treatment options is different from that of adults due to the consideration of the growth and developmental characteristics of children.

Polyetheretherketone (PEEK) as a Potential Material for the Repair of Maxillofacial Defect Compared with E-poly(tetrafluoroethylene) (e-PTFE) and Silicone.

Silicone and e-poly(tetrafluoroethylene) (e-PTFE) are the most commonly used artificial materials for repairing maxillofacial bone defects caused by facial trauma and tumors. However, their use is limited by poor histocompatibility, unsatisfactory support, and high infection rates. Polyetheretherketone (PEEK) has excellent mechanical strength and biocompatibility, but its application to the repair of maxillofacial bone defects lacks a theoretical basis. The microstructure and mechanical properties of e-PTFE, silicone, and PEEK were evaluated by electron microscopy, BOSE machine, and Fourier transformed infrared spectroscopy. Mouse fibroblast L929 cells were incubated on the surface of the three materials to assess cytotoxicity and adhesion. The three materials were implanted onto the left femoral surface of 90 male mice, and samples of the implants and surrounding soft tissues were evaluated histologically at 1, 2, 4, 8, and 12 weeks post-surgery. PEEK had a much higher Young's modulus than either e-PTFE or silicone (p < 0.05 each), and maintained high stiffness without degradation long after implantation. Both PEEK and e-PTFE facilitated L929 cell adhesion, with PEEK having lower cytotoxicity than e-PTFE and silicone (p < 0.05 each). All three materials similarly hindered the motor function of mice 12 weeks after implantation (p > 0.05 each). Connective tissue ingrowth was observed in PEEK and e-PTFE, whereas a fibrotic peri-prosthetic capsule was observed on the surface of silicone. The postoperative infection rate was significantly lower for both PEEK and silicone than for e-PTFE (p < 0.05 each). PEEK shows excellent biocompatibility and mechanical stability, suggesting that it can be effective as a novel implant to repair maxillofacial bone defects.

3D‐printed degradable hydroxyapatite bioactive ceramics for skull regeneration

AbstractHydroxyapatite (HA) bioceramics have been extensively employed as bone tissue scaffolds owing to their biodegradability and osteoinductivity. In our work, HA, a significant component of natural bone tissue used as the raw material to produce porous scaffolds employing three‐dimensional (3D)‐printing technology. Physical and chemical properties, porosity, and compression resistance of the scaffolds were investigated in vitro. The scaffold was confirmed to have a large number of interconnected pore structures on the surface and inside HA scaffolds showed good cell compatibility and cell adhesion in cell text. To analyze the effect of the scaffold on bone repair and regeneration in vivo, the large‐size defect of beagle skull was repaired with a 3D printing group and an autologous bone group (ABG) for 8 months. Images and histological analysis of the 3D printing group indicated better integration with adjacent tissues. However, there were obvious gaps in the ABG, which indicates weak bone regeneration ability of this group due to unmatched implant dimension. Immunohistochemistry and immunofluorescence results showed that 3D‐printed scaffolds had a highly vascularized structure. This study indicates that 3D‐printed bioceramics scaffolds that are osteoinductivity and biodegradable have great potential in maxillofacial bone regeneration.

Deep learning for detection and 3D segmentation of maxillofacial bone lesions in cone beam CT.

To develop an automated deep-learning algorithm for detection and 3D segmentation of incidental bone lesions in maxillofacial CBCT scans. The dataset included 82 cone beam CT (CBCT) scans, 41 with histologically confirmed benign bone lesions (BL) and 41 control scans (without lesions), obtained using three CBCT devices with diverse imaging protocols. Lesions were marked in all axial slices by experienced maxillofacial radiologists. All cases were divided into sub-datasets: training (20,214 axial images), validation (4530 axial images), and testing (6795 axial images). A Mask-RCNN algorithm segmented the bone lesions in each axial slice. Analysis of sequential slices was used for improving the Mask-RCNN performance and classifying each CBCT scan as containing bone lesions or not. Finally, the algorithm generated 3D segmentations of the lesions and calculated their volumes. The algorithm correctly classified all CBCT cases as containing bone lesions or not, with an accuracy of 100%. The algorithm detected the bone lesion in axial images with high sensitivity (95.9%) and high precision (98.9%) with an average dice coefficient of 83.5%. The developed algorithm detected and segmented bone lesions in CBCT scans with high accuracy and may serve as a computerized tool for detecting incidental bone lesions in CBCT imaging. Our novel deep-learning algorithm detects incidental hypodense bone lesions in cone beam CT scans, using various imaging devices and protocols. This algorithm may reduce patients' morbidity and mortality, particularly since currently, cone beam CT interpretation is not always preformed. • A deep learning algorithm was developed for automatic detection and 3D segmentation of various maxillofacial bone lesions in CBCT scans, irrespective of the CBCT device or the scanning protocol. • The developed algorithm can detect incidental jaw lesions with high accuracy, generates a 3D segmentation of the lesion, and calculates the lesion volume.

Prominent osteolysis in the maxilla: case report of an odontogenic fibroma mimicking a cyst

BackgroundOdontogenic fibroma (OF) is a rare benign odontogenic tumor of ectomesenchymal origin, mostly affecting the tooth-bearing portions of the jaws in middle-aged patients. Whilst small lesions tend to be clinically asymptomatic, varying unspecific clinical symptoms occur with an increase in size and may mimic odontogenic or other maxillofacial bone tumors, cysts, or fibro-osseous lesions of the jaws.Case presentationA 31-year-old female patient presented with a hard, non-fluctuating protrusion in the vestibule of the upper right maxilla. It was visualized on cone beam computed tomography (CBCT) as space-occupying osteolysis with the displacement of the floor and facial wall of the maxillary sinus, mimicking a cyst-like lesion. The tissue was surgically removed and identified as an OF in the histopathological examination. One year after the surgery, restitution of regular sinus anatomy and physiological intraoral findings were observed.ConclusionsThis case report emphasizes that rare entities, like the maxillary OF presented, often demonstrate nonspecific clinical and radiological findings. Nevertheless, clinicians need to consider rare entities as possible differential diagnoses and plan the treatment accordingly. Histopathological examination is essential to conclude the diagnosis. OF rarely recur after proper enucleation.

Research progress on autologous vascularized graft bone implant repair for maxillofacial bone defect

Maxillofacial bone defect can seriously affect the patient's appearance, mastication, deglutition and speech function. At present, autologous bone grafting combined with implant repair is an effective method for reconstruction of maxillofacial bone defects. Due to the differences in density, nutrition, immunity and other aspects of bone graft at different donor sites, there may be a potential impact on implant repair. In this paper, the biological characteristics of vascularized autologous bone used in maxillofacial bone defect repair were reviewed, and the risk factors of implantation on the bone graft were discussed. It provides support for clinicians in the selection of bone graft donor site and the design of prosthesis.

Head and Neck Tumor Histopathological Image Representation with Pr with Pre- Trained Conv ained Convolutional Neur olutional Neural Network and Vision al Network and Vision Transformer

Image representation via machine learning is an approach to quantitatively represent histopathological images of head and neck tumors for future applications of artificial intelligence-assisted pathological diagnosis systems. Objective: This study compares image representations produced by a pre-trained convolutional neural network (VGG16) to those produced by a vision transformer (ViT-L/14) in terms of the classification performance of head and neck tumors. Methods: Whole-slide images of five oral tumor categories (n = 319 cases) were analyzed. Image patches were created from manually annotated regions at 4096, 2048, and 1024 pixels and rescaled to 256 pixels. Image representations were classified by logistic regression or multiclass Support Vector Machines for binary or multiclass classifications, respectively. Results: VGG16 with 1024 pixels performed best for benign and malignant salivary gland tumors (BSGT and MSGT) (F1 = 0.703 and 0.803). VGG16 outperformed ViT for BSGT and MSGT with all magnification levels. However, ViT outperformed VGG16 for maxillofacial bone tumors (MBTs), odontogenic cysts (OCs), and odontogenic tumors (OTs) with all magnification levels (F1 = 0.780; 0.874; 0.751). Conclusion: Being more texture-biased, VGG16 performs better in representing BSGT and MSGT

Uremic Leontiasis Ossea Secondary to Hyperparathyroidism in Three Patients with End Stage Renal Disease

Renal osteodystrophy is a common complication referring to the skeletal changes associated with the phosphocalcic disorders of chronic uremia in patients with end-stage kidney disease. Uremic leontiasis ossea (ULO) is a rare and severe form of renal osteodystrophy with characteristic overgrowth of the cranial vault and facial bones. Computed tomography (CT) findings are particularly characteristic and include serpiginous tunneling within the maxillofacial bones and cortical bone resorption. The recognition of its radiological appearance and abrupt management are essential to avoid its devastating esthetic and functional impairments. Today's better medical facilities have improved hemodialysis methods, and meticulous patient follow‐up has decreased the incidence of leontiasis. In this paper, we report three rare cases of patients with end stage renal failure who presented with multiple face swellings and were diagnosed with ULO.

Multidetector computed tomography in evaluation of maxillofacial injuries

Facial injuries occur in significant proportion in trauma patients requiring prompt diagnosis and management. The number of maxillofacial injuries is continuously increasing due to rise in traffic, failure to take preventive measures in the traffic leads to road traffic accidents, which is the main etiological factor in maxillofacial fractures. To study role of multidetector tomography in evaluation of maxillofacial injuries. To describe the advantages of 3D reconstructed images over axial images in the imaging of facial fractures. This cross-sectional study included 100 patients who underwent CT evaluation of facial bones when they presented with evidence of fracture of maxillofacial bones on a 64-slice volume scanner (SIEMENS SOMATOM definition) in Geetanjali Medical College and Hospital, Udaipur during February 2019 to July 2020. RTA comprised of 76.19% cases. Assault and fall from height were 11.42 and 12.38%. The maxilla, the walls of its sinus were the most commonly involved bone with 71.42% next was Naso-orbito-ethmoid 68.57%. Zygomatic bone and mandible fractures were 50 and 38.09%. The type 2 frontal bone fractures were commonly seen 12 (31.5%) followed by Type 3, 10 (26.02%), Type 4 &amp; Type 1 seen in 6 (15.7%) and Type 5 was the least common injury seen 4 (10.52%). The medial wall of the orbit was most commonly involved 49 (35.76%). Le Fort fracture lines were identified in 17 occasions with Le Fort II seen 9 (52.9%). The advantages of 3D images within the assessment of facial trauma might be described especially in mandible and cheekbone. 3D images were better within the identification of Le Fort fracture lines. The coronal reconstructed images are superior in the detection of fractures in the orbit and maxilla. 3D images have a limited role in fractures involving the naso-orbito-ethmoid region and also when there is minimal fracture displacement.

Support-less ceramic 3D printing of bioceramic structures using a hydrogel bath

Volumetric bone tissue defects are beyond the intrinsic regenerative capacity of bone tissue. With the recent development of ceramic 3D printing, various bioceramic scaffolds that can induce bone regeneration are being actively developed. However, hierarchical bone is complex, with overhanging structures that require additional sacrificial support during ceramic 3D printing. Not only can this increase the overall process time and material consumption, but breaks and cracks may occur when sacrificial supports are removed from fabricated ceramic structures. In this study, a support-less ceramic printing (SLCP) process using a hydrogel bath was developed to facilitate the manufacture of complex bone substitutes. A hydrogel bath, consisting of pluronic P123 with temperature-sensitive properties, mechanically supported the fabricated structure when the bioceramic ink was extruded into the bath and promoted the cement reaction to cure the bioceramic. SLCP enables the fabrication of complex bone constructs with overhanging structures, such as the mandible and maxillofacial bones, with reduced overall processing time and material consumption. Scaffolds fabricated by SLCP showed more cell adhesion, higher cell growth rate, and osteogenic protein expression due to their rougher surface than conventionally printed scaffolds. Hybrid scaffolds were fabricated by SLCP to co-print cells and bioceramics, and SLCP provided a cell-friendly environment, exhibiting high cell viability. SLCP enables control of the shape of various cells, bioactive substances, and bioceramics and thus can be used as an innovative 3D bioprinting technique to manufacture complex hierarchical bone structures.

The role of EMILIN-1 in the osteo/odontogenic differentiation of dental pulp stem cells

BackgroundHuman dental pulp stem cells (hDPSCs) may be the best choice for self-repair and regeneration of teeth and maxillofacial bone tissue due to their homogeneous tissue origin, high proliferation and differentiation rates, and no obvious ethical restrictions. Recently, several studies have shown that extracellular matrix (ECM) proteins can effectively regulate the proliferation and differentiation fate of mesenchymal stem cells (MSCs). However, the role of elastin microfibril interface-located protein-1 (EMILIN-1), a new ECM glycoprotein, in osteo/odontogenic differentiation of hDPSCs has not been reported. The aim of this study was to explore the effect of EMILIN-1 during osteo/odontogenic differentiation of hDPSCs.MethodshDPSCs were cultured in osteo/odontogenic induction medium. qPCR and Western blot analysis were performed to detect osteo/odonto-specific genes/proteins expression as well as the expression of EMILIN-1. After knockdown of Emilin-1 in hDPSCs with small interfering RNA and exogenous addition of recombinant human EMILIN-1 protein (rhEMILIN-1), Cell Counting Kit-8 assay, alkaline phosphatase staining, alizarin red S staining, qPCR and Western blot were performed to examine the effect of EMILIN-1 on proliferation and osteo/odontogenic differentiation of hDPSCs.ResultsDuring the osteo/odontogenic induction of hDPSCs, the expression of osteo/odonto-specific genes/proteins increased, as did EMILIN-1 protein levels. More notably, knockdown of Emilin-1 decreased hDPSCs proliferation and osteo/odontogenic differentiation, whereas exogenous addition of rhEMILIN-1 increased them.ConclusionsThese findings suggested that EMILIN-1 is essential for the osteo/odontogenic differentiation of hDPSCs, which may provide new insights for teeth and bone tissue regeneration.

Patterns of Maxillofacial Injures Caused by Motorcycle Accidents.

Introduction Motorcycles are used as a common means of transportation, and motorcycle accidents are responsible for a major portion of trauma injuries. Objectives The purpose of this study was to analyze the patterns of facial injuries in motorcyclists, to evaluate the types of injuries, and to investigate if the accident-related factors had any impact on the characteristics of the injuries. Methods This retrospective observational study included 74 patients with maxillofacial injuries following motorcycle-related accidents. Investigated data were divided into four main categories: sociodemographic, accident-related, injury-related, and treatment-related. Results All the patients were males with a mean age (±SD) of 25.03 (±9.986) years. Most accidents ( n = 44, 59.4%) occurred in the evening. Most of the patients ( n = 40, 54%) were traveling on motorcycle models that had maximum speed of over 120 km/h. Furthermore, 15 patients (18.9%) were under the influence of alcohol during the crashes and only one patient was wearing a helmet. Fractures of the maxillofacial bones were observed in 50 (67.5%) crash victims; 24 of them (48%) had middle third fractures, 11 (22%) had mandibular fractures, and 15 patients (30%) presented with a combination of lower, middle, and upper third fractures. Conclusion Almost all patients were not wearing helmets at the moment of the crash. The most common fractured site was the maxilla. The majority of the patients received surgical treatment. Increased enforcement of safety measures for riders and raising awareness about the dangers of motorcycle crashes are required measures to improve traffic safety and, ultimately, population health.

Identification of key pathways in zirconia/dental pulp stem cell composite scaffold-mediated macrophage polarization through transcriptome sequencing

ABSTRACT Seed cells and scaffold materials are essential components of tissue engineering. In this study, we investigated the key pathway of the zirconia/dental pulp stem cell composite scaffold in regulating macrophage polarization by transcriptome sequencing. We established N-rGO/ZrO2 composite scaffold and confirmed its structure using various analytical techniques, including SEM, TEM, FTIR, Raman spectra, XPS, and XRD. DPSCs were seeded onto N-rGO/ZrO2 composite scaffold material, and their proliferation, adhesion, and osteogenic differentiation were evaluated by CCK-8, immunofluorescence staining, ALP staining, and alizarin red staining. We then co-cultured DPSCs combined with N-rGO/ZrO2 as composite material with THP-1 cells in a transwell system to investigate the effect of the composite on macrophage polarization. The levels of pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes were assessed by RT-qPCR and western blot. Through bulk RNA sequencing, we detected the transcriptional characteristics of macrophages under the regulation of the composite materials, and identified the differential genes using the DEseq2 package. We also analyzed the cellular and molecular functions of differentially expressed genes (DEGs) in THP-1 cells with DPSCs combined with N-rGO/ZrO2 treatment using GO enrichment analysis and KEGG pathway enrichment analysis. Our results showed that N-rGO/ZrO2 composite scaffold promoted the proliferation, adhesion, and osteogenic differentiation of DPSCs. Moreover, N-rGO/ZrO2 composite scaffold combined with DPSCs regulated macrophage migration, polarization, and glycolysis. Mechanistically, the combination of N-rGO/ZrO2 composite materials and DPSCs regulated macrophage polarization by activating the TNF signaling pathway. This finding provides a new approach to the clinical preservation of maxillofacial bone defect repair.

Three-Dimensional Finite Element Analysis of Maxillary Protraction Using Diverse Modes of Rapid Palatal Expansion.

Three-dimensional finite elemental analysis (FEA) is a contemporary research instrument for the numeric simulation of a real physical system's mechanical process. FEAcan be used as a very effective tool to analyze and compare various aspects of rapid palatal expanders and to determine the stress distribution in maxillofacial bones and displacement and the biomechanical effects it has on the circummaxillary sutures. This study evaluates the effects of different modes of rapid palatal expansion on maxillary protraction as a treatment modality in skeletal Class III malocclusion by determining the stress and displacement along the circummaxillary sutures using the FEA. Initially, a three-dimensional finite element simulation of the maxillofacial skeleton and sutures was obtained by Mimics software (Leuven, Belgium) from the cone-beam computed tomography (Dentsply Sirona, USA) images of a 30-year-old adult with normal occlusion. A geometrical preparation of the three expansion appliances, (A) hybrid MARPE (miniscrew-assisted rapid palatal expander)appliance (Fav anchor, India), (B) tooth-borne HYRAX (hygenic rapid expander)appliance (Welcare orthodontics, Kerela), and (C) bone-borne modified MARPE appliance (Biomaterials, Korea), was transferred to ANSYS WORKBENCH, 2020 R1 software (ANSYS, Inc., USA), and three finite element models with each appliance were prepared. A protraction force of 500g was applied to the occlusal plane that is directed 20 degrees inferiorly. The tensile stress, compressive stress, and the amount of displacement on the circummaxillary sutures were assessed and compared in all the three appliances. Young's modulus (kg/mm2) and Poisson's ratio (V) were used to calculate the stress and displacement in sutures adjacent to the maxilla in different aspects. On analyzing the stress distribution, the tensile stress was found to be maximum in the medial aspect of the frontomaxillary suture of the bone-borne modified MARPE appliance (C), and the minimum tensile stress was found in the lateral aspect of the sphenozygomatic suture in hybrid MARPE (A). Again, the compressive stress distribution was found to be maximum in the medial aspect of the frontomaxillary suture in all three simulations and the minimum compressive stress in the superior aspect of the internasal suture in hybrid MARPE (A) along with the frontonasal suture at its medial aspect for tooth-borneHYRAX (B) and bone-bornemodified MARPE (C). Displacement of the maxilla in all the planes was observed to be the largest for the bone-borne modified MARPE (C) appliance. On the contrary, the minimum displacement was found in the tooth-borne HYRAX (B) appliance. Conclusion: The findings reveal that all three modes of rapid palatal expanders produced stress and displacement along the circummaxillary sutures on the application of protraction force with bone-borne modified MARPE being more effective in treating posterior crossbites thereby correcting the skeletal Class III malocclusions successfully.

Atf4 regulates angiogenic differences between alveolar bone and long bone macrophages by regulating M1 polarization, based on single-cell RNA sequencing, RNA-seq and ATAC-seq analysis

In the repair of maxillofacial bone defects, autogenous craniofacial bone can often provide superior clinical results over long bone grafts. Most current studies have focused on the osteogenic differences between alveolar bone marrow (ABM) and long bone marrow (LBM), however, studies about the angiogenic differences between the two are currently lacking. We downloaded single-cell RNA sequencing (scRNA-seq) of mouse ABM and LBM respectively from the public database, and the data were processed by using Seurat package. CellphoneDB2 results showed that macrophages had the strongest interaction with mesenchymal stem cells (MSCs) and endothelial cells (ECs). ELISA results confirmed that ABM macrophages secreted a higher level of vascular endothelial growth factor A (Vegfa) compared to LBM macrophages, which further promoted angiogenesis of ECs and MSCs. Using SCENIC package, six key transcription factors (TFs) were identified to regulate the difference between ABM and LBM macrophages, and activating transcription factor 4 (Atf4) was confirmed to be more expressed in ABM macrophages by polymerase chain reaction (PCR) and western blot (WB), with predicted target genes including Vegfa. Besides, the result of scRNA-seq implied ABM macrophages more in M1 status than LBM macrophages, which was confirmed by the following experiments. From the results of another assay for transposase accessible chromatin sequencing (ATAC-seq) and RNA-seq about M1 macrophages, Atf4 was also confirmed to regulate the M1 polarization. So, we suspected that Atf4 regulated the different expression of Vegfa between ABM and LBM macrophages by activating M1 polarization. After knocking down Atf4, the expression of M1 polarization markers and Vegfa were downregulated and vasculogenic differences were eliminated, which were subsequently reversed by the addition of LPS/IFN-γ. Our study might provide a new idea to improve the success rate of autologous bone grafting and treatment of oral diseases.

METTL3 potentiates osteogenic differentiation of bone marrow mesenchymal stem cells via IGF2BP1/m6A/RUNX2.

Maxillofacial bone defect is a critical obstacle for maxillofacial tumors and periodontal diseases. The osteogenic differentiation of bone marrow mesenchymal stem cells BMSCs is critical for maxillofacial osteogenesis and functional reconstruction. Here, our study focused on the functions and mechanism of N6-methyladenosine during BMSCs osteogenic differentiation BMSCs. Biofunctions of BMSCs were detected using ALP activity and alizarin red S staining assays. The molecular interaction within RNA/protein was identified by RNA immunoprecipitation and/or methylation immunoprecipitation. Results indicated that m6A 'writer' METTL3 upregulated during the osteogenic differentiation of BMSCs upon osteogenic induction. Functionally, assays' results revealed that METTL3 overexpression promoted the osteogenic differentiation of BMSC, while METTL3 knockdown repressed the osteogenic differentiation. Mechanistically, results revealed that RUNX2 mRNA was a m6A-methylated target by METTL3 at its 3'-UTR. Moreover, m6A reader IGF2BP1 recognized the m6A site on RUNX2 mRNA to enhance its stability. In conclusion, our findings revealed the novel roles of METTL3 in BMSCs osteogenic differentiation via the IGF2BP1/m6A/RUNX2 signaling axis of m6A-dependent manner, providing a potential therapeutic target for maxillofacial bone defects treatment.

Three-Dimensional Printing of a Polycaprolactone-Fluorapatite Nanocomposite Scaffold and Simulation of Its Mechanical Properties

Introduction: The use of porous nanobiocomposite scaffolds for maxillofacial fractures and internal surface optimization of artificial grafts utilizing nanotechnology can improve cell adhesion, mechanical properties, and adsorption rate. Porous scaffolds have been the subject of numerous investigations, especially for broken and damaged parts of the facial bone. The goal of this study was to look into the biological, experimental, and numerical study of the mechanical properties of porous scaffolds under static loading conditions.Materials &amp; Methods: In this study, a bone scaffold of polycaprolactone- Fluorapatite (PCL / nFA) nanocomposite materials containing (0, 10, 20, 30 %wt.) Fluorapatite nanoparticles was designed and manufactured using a 3D printer with Fused Deposition Modelling (FDM) process. The scaffolds were designed in SolidWorks software with 70% porosity and then transferred to Abaqus software for simulation.Results: In addition, following 28 days of immersion in the simulated body fluid, the bioactivity test of pure and composite scaffolds showed that the PCL /20nFA composite sample produced the most apatite on the surface. DAPI staining and fluorescent microscopy observation, confirm cell viability on the 3D printed scaffold.Conclusion: The Von Mises stress and compressive test simulations revealed that the porous scaffold model may be used for maxillofacial bone replacement and has good mechanical strength and stability.

Maxillofacial fracture detection and classification in computed tomography images using convolutional neural network-based models

The purpose of this study was to evaluate the performance of convolutional neural network-based models for the detection and classification of maxillofacial fractures in computed tomography (CT) maxillofacial bone window images. A total of 3407 CT images, 2407 of which contained maxillofacial fractures, were retrospectively obtained from the regional trauma center from 2016 to 2020. Multiclass image classification models were created by using DenseNet-169 and ResNet-152. Multiclass object detection models were created by using faster R-CNN and YOLOv5. DenseNet-169 and ResNet-152 were trained to classify maxillofacial fractures into frontal, midface, mandibular and no fracture classes. Faster R-CNN and YOLOv5 were trained to automate the placement of bounding boxes to specifically detect fracture lines in each fracture class. The performance of each model was evaluated on an independent test dataset. The overall accuracy of the best multiclass classification model, DenseNet-169, was 0.70. The mean average precision of the best multiclass detection model, faster R-CNN, was 0.78. In conclusion, DenseNet-169 and faster R-CNN have potential for the detection and classification of maxillofacial fractures in CT images.