Spontaneous Recovery of Pathological Fracture Caused by Medication-Related Osteonecrosis of the Jaw.

Pathological fracture is one of the most serious complications in medication-related osteonecrosis of the jaw (MRONJ). This case is a report of an 87-year-old woman who had been diagnosed with pathological fracture due to MRONJ. The authors performed minimally invasive and conservative treatment, such as intraoral dressing, antibiotic therapy, and simple debridement, for patients with pathologic fractures due to MRONJ. After 1 year, the inflammatory symptoms disappeared and pathological fractures spontaneously recovered.

Temporomandibular Joint Space in Mandibular Prognathism.

This study compared the temporomandibular joint (TMJ) space between patients with normal and prognathic mandibles. The study included a total of 68 Korean individuals, and the TMJ space was measured using computed tomography. Patients with normal SNB values (normal mandible) were classified into Group 1. Patients with high SNB values (prognathic mandibles) were categorized into Group 2. The TMJ space was defined as the distance between the condylar process and the mandibular fossa, and it was significantly different between Groups 1 and 2 (1.94±0.07 mm versus 1.50±0.05 mm, P< 0.01). This study confirmed that the TMJ space in patients with prognathic mandibles is narrower than that in patients with normal mandibles.

Implant in the Area of Cemento-osseous Dysplasia: Secondary Infection After Osseointegration and Loading.

This case report presents the clinical details of a 60-year-old woman who experienced a secondary infection 5 years postimplant placement and loading in a region affected by cemento-osseous dysplasia (COD). We conducted the simultaneous removal of the implant and the COD mass, which had become osseointegrated with the implant. Healing of the affected area was successful. Caution is paramount during implant placement in COD-affected areas, particularly during the intermediate and osteosclerotic stages, due to compromised vascularity.

Deep learning-based prediction of osseointegration for dental implant using plain radiography.

BACKGROUND: In this study, we investigated whether deep learning-based prediction of osseointegration of dental implants using plain radiography is possible. METHODS: Panoramic and periapical radiographs of 580 patients (1,206 dental implants) were used to train and test a deep learning model. Group 1 (338 patients, 591 dental implants) included implants that were radiographed immediately after implant placement, that is, when osseointegration had not yet occurred. Group 2 (242 patients, 615 dental implants) included implants radiographed after confirming successful osseointegration. A dataset was extracted using random sampling and was composed of training, validation, and test sets. For osseointegration prediction, we employed seven different deep learning models. Each deep-learning model was built by performing the experiment 10 times. For each experiment, the dataset was randomly separated in a 60:20:20 ratio. For model evaluation, the specificity, sensitivity, accuracy, and AUROC (Area under the receiver operating characteristic curve) of the models was calculated. RESULTS: The mean specificity, sensitivity, and accuracy of the deep learning models were 0.780-0.857, 0.811-0.833, and 0.799-0.836, respectively. Furthermore, the mean AUROC values ranged from to 0.890-0.922. The best model yields an accuracy of 0.896, and the worst model yields an accuracy of 0.702. CONCLUSION: This study found that osseointegration of dental implants can be predicted to some extent through deep learning using plain radiography. This is expected to complement the evaluation methods of dental implant osseointegration that are currently widely used.

Reconstruction of Mandibular Defects With Bone Marrow-Derived Stem Cells in Odontogenic Myxoma.

Odontogenic myxoma is a benign tumor, mostly located in the mandible. It shows locally aggressive behavior and requires surgical removal. Common treatment options for reconstructing the bone defects are immediate or delayed autologous bone graft or free flap. In this article, the authors present the successful reconstruction with autogenous bone graft and autologous human bone marrow mesenchymal stem, followed by distraction osteogenesis, dental implant placement and prosthodontic restoration in the mandibular defect.

Mandibular Regeneration With Autologous Human Bone Marrow Derived Mesenchymal Stem Cells to Treat Unicystic Ameloblastoma: A Clinical Report.

Ameloblastoma is a rare, benign tumor found in the jaw. These tumors have a tendency for locally aggressive expansion, and thus require surgical removal. For the previous 3 decades, autologous bone grafting and free flap surgeries have been most commonly used to correct bone defects after surgical removal of the lesion. In this report, the authors describe a case of unicystic ameloblastoma in a 14-year-old girl who was successfully treated with mandibular regeneration, attained by autologous human bone marrow mesenchymal stem cells without any autologous bone graft and free flap transfer. This case shows that autologous human bone marrow mesenchymal stem cells can be used as an alternative method to autologous bone graft and free flap transfer in a large bone defect of the jaw.

Factors affecting forced eruption duration of impacted and labially displaced canines.

INTRODUCTION: Patients with impacted maxillary canines typically endure long treatment time, and reliable pretreatment estimates of orthodontic treatment duration would be beneficial to patients and clinicians. The purpose of this study was to identify factors that affect the duration of forced eruption for impacted maxillary canines. METHODS: Data from treatment records and radiographic scans of 27 patients with 29 impacted and labially displaced maxillary canines (25 unilateral, 2 bilateral) were collected. The patients underwent surgical and orthodontic interventions to bring the canine into the dental arch. Linear and angular measurements between the cusp tip and various reference planes were made on 3-dimensional images. Measurements associated with dental follicle, bone density, and canine root length were also obtained. Data were analyzed using simple linear regression and stepwise regression analysis. RESULTS: A total of 29 treated canines moved into the arch over a period of 13.0 ± 8.3 months (range, 5-33 months). Simple regression analysis showed that the only significant factor, with duration of traction as the dependent factor, was pretreatment inclination of the canines toward the midsagittal plane; stepwise regression analysis indicated a strong direct correlation between the duration of traction and this factor. The other variables were not significantly associated with the duration of traction. CONCLUSIONS: The inclination of canines toward the midsagittal plane was found to be a reliable predictor of the duration of forced eruption for impacted maxillary canines.

Application of Autologous Human Bone Marrow-Derived Mesenchymal Stem Cells in Distraction Osteogenesis for the Treatment of Bilateral Mandibular Hypoplasia.

Distraction osteogenesis a surgical procedure conducted to improve craniofacial deformities. Compared with conventional operations, this technique has advantages such as the ability to lengthen the soft tissue and hard tissue. Therefore, this method is used to treat severe craniofacial abnormalities.The major disadvantage of distraction osteogenesis is the long treatment period. If the consolidation period is not sufficiently long after the distraction period, complications such as discontinuity or contraction of newly formed bone may occur. Recently, many researchers have attempted to develop methods for enhancing the ossification of newly formed bone, reducing shrinkage, and shortening the overall treatment period.The authors injected autologous bone marrow-derived mesenchymal stem cells during the consolidation phase after distraction osteogenesis surgery in a bilateral mandibular hypoplasia patient. Here, the authors report the treatment results, which were found to be favorable.

Spontaneous Union of an Accidentally Fractured Proximal Segment During Vertical Ramus Osteotomy.

After sawing in the intraoral vertical ramus osteotomy, in the case of an incomplete amputation, the proximal segment is split using the osteotome. Unfortunately, in this case, the proximal segment was accidentally fractured. The operation was completed without performing any other fixation. Postoperatively intermaxillary fixation was performed and kept for a week, followed by physical therapy, which was initiated immediately after. The patient was closely observed for 6 months. No abnormal findings were detected clinically, and the union of bone was verified.

Volumetric Change in the Masseter and Lateral Pterygoid after Mandibular Setback.

In this study, we evaluated changes in the masseter and lateral pterygoid muscles in the prognathic mandible group after a mandibular setback by comparing the volume-to-length ratios. Preoperative and postoperative 1-year computed tomography was used to calculate the volume-to-length ratio of the lateral pterygoid and masseter muscle in 60 Korean individuals. Three-dimensional images were reconstructed, the results of which showed no significant differences in the volume-to-length ratios of the masseter and lateral pterygoid muscles after a mandibular setback (p > 0.05). This result was found for both vertical ramus osteotomy and sagittal split ramus osteotomy, and for both males and females. No significant differences in the volume-to-length ratio of the masseter and lateral pterygoid muscles were found up to 1 year after a mandibular setback. Therefore, this study can contribute to the prediction of soft-tissue profiles after mandibular setback.

Three-Dimensional Postoperative Results Prediction for Orthognathic Surgery through Deep Learning-Based Alignment Network.

To date, for the diagnosis of dentofacial dysmorphosis, we have relied almost entirely on reference points, planes, and angles. This is time consuming, and it is also greatly influenced by the skill level of the practitioner. To solve this problem, we wanted to know if deep neural networks could predict postoperative results of orthognathic surgery without relying on reference points, planes, and angles. We use three-dimensional point cloud data of the skull of 269 patients. The proposed method has two main stages for prediction. In step 1, the skull is divided into six parts through the segmentation network. In step 2, three-dimensional transformation parameters are predicted through the alignment network. The ground truth values of transformation parameters are calculated through the iterative closest points (ICP), which align the preoperative part of skull to the corresponding postoperative part of skull. We compare pointnet, pointnet++ and pointconv for the feature extractor of the alignment network. Moreover, we design a new loss function, which considers the distance error of transformed points for a better accuracy. The accuracy, mean intersection over union (mIoU), and dice coefficient (DC) of the first segmentation network, which divides the upper and lower part of skull, are 0.9998, 0.9994, and 0.9998, respectively. For the second segmentation network, which divides the lower part of skull into 5 parts, they were 0.9949, 0.9900, 0.9949, respectively. The mean absolute error of transverse, anterior-posterior, and vertical distance of part 2 (maxilla) are 0.765 mm, 1.455 mm, and 1.392 mm, respectively. For part 3 (mandible), they were 1.069 mm, 1.831 mm, and 1.375 mm, respectively, and for part 4 (chin), they were 1.913 mm, 2.340 mm, and 1.257 mm, respectively. From this study, postoperative results can now be easily predicted by simply entering the point cloud data of computed tomography.

Deep learning based prediction of extraction difficulty for mandibular third molars.

This paper proposes a convolutional neural network (CNN)-based deep learning model for predicting the difficulty of extracting a mandibular third molar using a panoramic radiographic image. The applied dataset includes a total of 1053 mandibular third molars from 600 preoperative panoramic radiographic images. The extraction difficulty was evaluated based on the consensus of three human observers using the Pederson difficulty score (PDS). The classification model used a ResNet-34 pretrained on the ImageNet dataset. The correlation between the PDS values determined by the proposed model and those measured by the experts was calculated. The prediction accuracies for C1 (depth), C2 (ramal relationship), and C3 (angulation) were 78.91%, 82.03%, and 90.23%, respectively. The results confirm that the proposed CNN-based deep learning model could be used to predict the difficulty of extracting a mandibular third molar using a panoramic radiographic image.

Deep learning based discrimination of soft tissue profiles requiring orthognathic surgery by facial photographs.

Facial photographs of the subjects are often used in the diagnosis process of orthognathic surgery. The aim of this study was to determine whether convolutional neural networks (CNNs) can judge soft tissue profiles requiring orthognathic surgery using facial photographs alone. 822 subjects with dentofacial dysmorphosis and / or malocclusion were included. Facial photographs of front and right side were taken from all patients. Subjects who did not need orthognathic surgery were classified as Group I (411 subjects). Group II (411 subjects) was set up for cases requiring surgery. CNNs of VGG19 was used for machine learning. 366 of the total 410 data were correctly classified, yielding 89.3% accuracy. The values of accuracy, precision, recall, and F1 scores were 0.893, 0.912, 0.867, and 0.889, respectively. As a result of this study, it was found that CNNs can judge soft tissue profiles requiring orthognathic surgery relatively accurately with the photographs alone.

Volumetric characteristics of prognathic mandible revealed by skeletal unit analysis.

The purpose of this study was to evaluate the skeletal units of a normal mandible (class I) and a prognathic mandible (class III), to compare the groups, and to investigate the key functional unit responsible for mandibular prognathism. Hemi-mandibles of 101 cases were evaluated by cone-beam computed tomography. Of these, 50 cases had Class I and 51 had Class III mandibles. The length, volume, and volume/length ratio of each skeletal unit were measured. The ratios of the condyle, body unit, and sum of the hemi-mandible between Class I and Class III showed statistically significant results (P<0.05). However, the ratios of angle, coronoid, and symphysis units did not show any statistical significance on comparison. Dependent on gender, in males the ratio of the condyle of the hemi-mandible showed statistically significant results (P<0.05). Meanwhile in females the ratio of the body and sum of the hemi-mandible showed statistically significant results (P<0.05). Accordingly, the mandibular body and condylar units are thinner in mandibular prognathism. On the basis of the functional matrix theory to determine the aetiology of mandibular prognathism, the key skeletal units are the body and condylar units.

Rotation tendency of the posteriorly displaced proximal segment after vertical ramus osteotomy.

Intraoral Vertical Ramus Osteotomy (IVRO) is one of the operative techniques used for orthognathic surgery. The aim of this study was to assess the posterior displacement of the proximal segment in patients undergoing IVRO at 1-year follow-up. In total, 52 hemimandibles from 26 patients who underwent IVRO in whom the proximal segment was posteriorly displaced without overlap with the distal segment at immediate post-operation (Imm) (30 cases, experimental group), and 26 patients in whom the proximal segment was not posteriorly displaced with overlap with the distal segment (Imm) (22 cases, control group) under three-dimensional computed tomography (3D CT) were included in the study. To analyze the movement of segments, the positions of the mid condyle point (MCP) and angle of condyle line (Con) were determined and the movement of the ramus angle (posterior edge of proximal segments) was measured at the proximal segment. Regression of the proximal segment in sagittal direction of the MCP was observed in both groups and all directions of the ramus angle in the experimental group, and only sagittal direction in the control group. In conclusion, posterior displacement of the proximal segment after IVRO showed tendency to regress its original position.

Angiogenin-loaded fibrin/bone powder composite scaffold for vascularized bone regeneration.

BACKGROUND: Angiogenin (ANG) is a potent stimulator of angiogenesis. The aim of this study was to fabricate an ANG-loaded scaffold and to evaluate its angiogenic and osteogenic effects. In this study, we fabricated an ANG-loaded scaffold using bovine bone powder and fibrin glue. We then evaluated the structural, morphological, and mechanical properties of the scaffold and the in vitro release profile of ANG. Cell proliferation, viability, and adhesion were evaluated using endothelial cells in vitro, and angiogenesis and new bone formation were evaluated using a rabbit calvarial defect model in vivo. RESULTS: Micro-computed tomography imaging showed that the bone powder was uniformly distributed in the scaffold, and scanning electron microscopy showed that the bone powder was bridged by polymerized fibrin. The porosity and compressive strength of the scaffolds were ~60 % and ~0.9 MPa, respectively, and were not significantly altered by ANG loading. In vitro, at 7 days, approximately 0.4 µg and 1.3 µg of the ANG were released from the FB/ANG 0.5 and FB/ANG 2.0, respectively and sustained slow release was observed until 25 days. The released ANG stimulated cell proliferation and adherence and was not cytotoxic. Furthermore, in vivo implantation resulted in enhanced angiogenesis, and new bone formation depended on the amount of loaded ANG. CONCLUSIONS: These studies demonstrate that a fibrin and bone powder scaffold loaded with ANG might be useful to promote bone regeneration by enhanced angiogenesis.