A Deep Learning-Based Semantic Segmentation Model Using MCNN and Attention Layer for Human Activity Recognition.

With the development of wearable devices such as smartwatches, several studies have been conducted on the recognition of various human activities. Various types of data are used, e.g., acceleration data collected using an inertial measurement unit sensor. Most scholars segmented the entire timeseries data with a fixed window size before performing recognition. However, this approach has limitations in performance because the execution time of the human activity is usually unknown. Therefore, there have been many attempts to solve this problem through the method of activity recognition by sliding the classification window along the time axis. In this study, we propose a method for classifying all frames rather than a window-based recognition method. For implementation, features extracted using multiple convolutional neural networks with different kernel sizes were fused and used. In addition, similar to the convolutional block attention module, an attention layer to each channel and spatial level is applied to improve the model recognition performance. To verify the performance of the proposed model and prove the effectiveness of the proposed method on human activity recognition, evaluation experiments were performed. For comparison, models using various basic deep learning modules and models, in which all frames were classified for recognizing a specific wave in electrocardiography data were applied. As a result, the proposed model reported the best F1-score (over 0.9) for all kinds of target activities compared to other deep learning-based recognition models. Further, for the improvement verification of the proposed CEF method, the proposed method was compared with three types of SW method. As a result, the proposed method reported the 0.154 higher F1-score than SW. In the case of the designed model, the F1-score was higher as much as 0.184.

Markerless 3D Skeleton Tracking Algorithm by Merging Multiple Inaccurate Skeleton Data from Multiple RGB-D Sensors.

Skeleton data, which is often used in the HCI field, is a data structure that can efficiently express human poses and gestures because it consists of 3D positions of joints. The advancement of RGB-D sensors, such as Kinect sensors, enabled the easy capture of skeleton data from depth or RGB images. However, when tracking a target with a single sensor, there is an occlusion problem causing the quality of invisible joints to be randomly degraded. As a result, multiple sensors should be used to reliably track a target in all directions over a wide range. In this paper, we proposed a new method for combining multiple inaccurate skeleton data sets obtained from multiple sensors that capture a target from different angles into a single accurate skeleton data. The proposed algorithm uses density-based spatial clustering of applications with noise (DBSCAN) to prevent noise-added inaccurate joint candidates from participating in the merging process. After merging with the inlier candidates, we used Kalman filter to denoise the tremble error of the joint's movement. We evaluated the proposed algorithm's performance using the best view as the ground truth. In addition, the results of different sizes for the DBSCAN searching area were analyzed. By applying the proposed algorithm, the joint position accuracy of the merged skeleton improved as the number of sensors increased. Furthermore, highest performance was shown when the searching area of DBSCAN was 10 cm.

The Effect of Polydeoxyribonucleotide Extracted from Salmon Sperm on the Restoration of Bisphosphonate-Related Osteonecrosis of the Jaw.

Bisphosphonates (BPs) used for treating skeletal diseases can induce bisphosphonate-related osteonecrosis of the jaw (BRONJ). Despite much effort, effective remedies are yet to be established. In the present study, we investigated the feasibility of polydeoxyribonucleotide (PDRN) extracted from salmon sperm for the treatment of BRONJ, in a BRONJ-induced rat model. Compared with BRONJ-induced samples, PDRN-treated samples exhibited lower necrotic bone percentages and increased numbers of blood vessels and attached osteoclast production. Moreover, local administration of PDRN at a high concentration (8 mg/kg) remarkably resolved the osteonecrosis. Findings from this study suggest that local administration of PDRN at a specific concentration may be considered clinically for the management of BRONJ.

The Cocktail Effect of BMP-2 and TGF-ß1 Loaded in Visible Light-Cured Glycol Chitosan Hydrogels for the Enhancement of Bone Formation in a Rat Tibial Defect Model.

Bone tissue engineering scaffolds offer the merits of minimal invasion as well as localized and controlled biomolecule release to targeted sites. In this study, we prepared injectable hydrogel systems based on visible light-cured glycol chitosan (GC) hydrogels containing bone morphogenetic protein-2 (BMP-2) and/or transforming growth factor-beta1 (TGF-ß1) as scaffolds for bone formation in vitro and in vivo. The hydrogels were characterized by storage modulus, scanning electron microscopy (SEM) and swelling ratio analyses. The developed hydrogel systems showed controlled releases of growth factors in a sustained manner for 30 days. In vitro and in vivo studies revealed that growth factor-loaded GC hydrogels have no cytotoxicity against MC3T3-E1 osteoblast cell line, improved mRNA expressions of alkaline phosphatase (ALP), type I collagen (COL 1) and osteocalcin (OCN), and increased bone volume (BV) and bone mineral density (BMD) in tibia defect sites. Moreover, GC hydrogel containing BMP-2 (10 ng) and TGF-ß1 (10 ng) (GC/BMP-2/TGF-ß1-10 ng) showed greater bone formation abilities than that containing BMP-2 (5 ng) and TGF-ß1 (5 ng) (GC/BMP-2/TGF-ß1-5 ng) in vitro and in vivo. Consequently, the injectable GC/BMP-2/TGF-ß1-10 ng hydrogel may have clinical potential for dental or orthopedic applications.

Dual Effect of Curcumin/BMP-2 Loaded in HA/PLL Hydrogels on Osteogenesis In Vitro and In Vivo.

In the present study, we evaluated the potential of poly-l-lysine/hyaluronic acid (HA/PLL) hydrogels containing curcumin (CUR) and bone morphogenetic protein-2 (BMP-2) as bone tissue regeneration scaffolds. Hydrogels HP-1˜2 were formed by amide bonds via the condensation reactions between 0.02 µmol HA and 0.06­0.12 µmol poly-l-lysine · hydrobromide (PLL · HBr). Physical, chemical, and thermal analyses revealed that the amount of PLL · HBr significantly influenced hydrogel properties. Based on an In Vitro MG-63 cell proliferation test, HP-1˜2 were cytocompatible, and all hydrogels containing different amounts of CUR and BMP-2, except for HA0.02/PLL0.06/CUR20/BMP-2100 (HPCB-4), resulted in cell proliferation above 80%. An In Vitro release test showed that CUR and BMP-2 were consistently released from HA0.02/PLL0.06/CUR15 (HPC), HA0.02/PLL0.06/BMP-2100 (HPB), HA0.02/PLL0.06/CUR15/BMP-210 , 50 , or 100 (HPCB-1˜3), and HA0.02/PLL0.06/CUR10 or 20/BMP-2100 (HPCB-4˜5) for 7 and 28 days, respectively. In Vitro ALP activity and calcium deposition and In Vivo micro-computed tomography (micro-CT) tests demonstrated the potential application of HPCB-3 as bone tissue regeneration scaffolds, suggesting that bone tissue regeneration can be optimized by controlling the amounts of CUR and BMP-2.

Supramolecular Hydrogels Based on MPEG-Grafted Hyaluronic Acid and α-CD Containing HP-ß-CD/Simvastatin Enhance Osteogenesis In Vivo.

Simvastatin (SIM) accelerates new bone formation both in vitro and In Vivo by enhancing the expression of recombinant human bone morphogenetic protein-2 (rhBMP-2). In this study, we evaluated the effect of water-solubility of SIM on new bone formation by preparing two types of supramolecular hydrogels: pseudopolyrotaxanes (PPRXs) based on metoxy polyethyleneglycol-grafted hyaluronic acid (MPEG-g-HA) and α-cyclodextrin (α-CD) containing water-soluble hydroxypropyl ß-cyclodextrin/simvastatin inclusion complex (HP-ß-CD-ic-SIM; MPEG-g-HA/α-CD/HP-ß-CD-ic-SIM) or only SIM (MPEG-g-HA/α-CD/SIM). As compared to MPEG-g- HA/α-CD/SIM, SIM was more rapidly released from MPEG-g-HA/α-CD/HP-ß-CD-ic-SIM in a sustained manner owing to increased water-solubility. New bone actively formed at the calvarial defect site in a rabbit model 4 weeks after implantation, as examined by micro computed tomography (micro CT), hematoxylin and eosin (H&E) staining, and Goldner's trichrome staining. The results showed that the water-solubility of SIM plays a significant role in enhancing new bone formation in vivo.

In Vitro Osteogenic Differentiation Enhanced by Zirconia Coated with Bone Morphogenetic Protein-2.

In this study we report on the effectiveness of click chemistry-enhanced zirconium dioxide (ZrO2-3) for the immobilization of biomolecules, and the enhancement of osteoblastic differentiation of MC3T3-E1 cells by bone morphogenetic protein-2 (BMP-2) immobilized on ZrO2-6. The surfaces of ZrO2-1 through 6 were characterized by scanning electron microscopy (SEM), static contact angles, and X-ray photoelectron spectroscopy (XPS) measurements. The results from these tests indicated that ZrO2-1 was successfully surface-modified via click chemistry (ZrO2-3). Through quantitative analysis of heparin immobilized on ZrO2-5, we found that ZrO2-3 was a useful tool for immobilizing biomolecules such as heparin. Release tests of BMP-2 from ZrO2-6 showed well-controlled release kinetics over a period of 28 days. MC3T3-E1 cell proliferation tests indicated that ZrO2-6 was highly biocompatible with these cells. Through In Vitro tests such as alkaline phosphatase (ALP) activity, calcium deposition, and real-time polymerase chain reaction (real-time PCR), we found that ZrO2-6 was a useful tool for enhancing osteoblastic differentiation of MC3T3-E1 cells.

Preparation and Evaluation of Dexamethasone (DEX)/Growth and Differentiation Factor-5 (GDF-5) Surface-Modified Titanium Using ß-Cyclodextrin-Conjugated Heparin (CD-Hep) for Enhanced Osteogenic Activity In Vitro and In Vivo.

The most ideal implant models in the dental and orthopedic fields to minimize the failure rate of implantation involve the improvement of osseointegration with host bone. Therefore, a focus of this study is the preparation of surface-modified titanium (Ti) samples of disc and screw types using dexamethasone (DEX) and/or growth and differentiation factor-5 (GDF-5), as well as the evaluation of their efficacies on bone formation in vitro and in vivo. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle measurement were used to evaluate the surface chemical composition, surface morphology and wettability, respectively. The results showed that implant surfaces were successfully modified with DEX and/or GDF-5, and had rough surfaces along with hydrophilicity. DEX, GDF-5 or DEX/GDF-5 on the surface-modified samples were rapidly released within one day and released for 28 days in a sustained manner. The proliferation and bone formation of MC3T3-E1 cells cultured on pristine and surface-modified implants in vitro were examined by cell counting kit-8 (CCK-8) assay, as well as the measurements of alkaline phosphatase (ALP) activity and calcium deposition, respectively. MC3T3-E1 cells cultured on DEX/GDF-5-Ti showed noticeable ALP activity and calcium deposition in vitro. Active bone formation and strong osseointegration occurred at the interface between DEX/GDF-5-Ti and host bone, as evaluated by micro computed-tomography (micro CT) analysis. Surface modification using DEX/GDF-5 could be a good method for advanced implants for orthopaedic and dental applications.

Surface Modification of Titanium with BMP-2/GDF-5 by a Heparin Linker and Its Efficacy as a Dental Implant.

In this study, we prepared human bone morphogenetic protein-2 (hBMP-2)/human growth and differentiation factor-5 (hGDF-5)-coated titanium (Ti) disc and screw types for controlled release of the growth factors (GFs). The two growth factors were coated onto Ti with a smooth surface using their specific interaction with heparin, because they have heparin binding sites in their molecular structures. Efficacy of the two growth factor-coated Ti for enhancement of bone formation and osseointegration was compared to pristine Ti, and hBMP-2- and hGDF-5-coated Ti in vivo. The surface chemical composition, surface morphology, and wettability characteristics of the metal samples were determined by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and contact angle measurement, respectively. The initial burst of hBMP-2, hGDF-5, and their combination, occurred within one day of the release study, resulting in 12.5%, 4.5%, and 13.5%/3.2%, and then there was a sustained, even release of these two growth factors from the coated metal for 30 days. In vitro tests revealed that MC3T3-E1 cells cultured on the two growth factor-coated Ti had a higher proliferation rate and a higher activity for alkaline phosphatase (ALP), which led to a larger amount of calcium deposition and larger expressions of type I collagen (COL 1), ALP, and osteocalcin (OCN) mRNAs. In vivo animal tests using ten white New Zealand rabbits showed that the two growth factor-coated Ti enhanced bone formation and osseointegration at the interface between the implants and host bone. In addition, histological evaluation showed that bone remodeling, including bone formation by osteoblasts and bone resorption by osteoclasts, actively occurred between the two growth factor-coated Ti and host bone. Consequently, it is suggested that Ti surface modification with the combination of hBMP-2 and hGDF-5 for the two growth factor-coated Ti implants can improve the clinical properties of implants for orthopedic and dental applications.

Visible Light-Cured Glycol Chitosan Hydrogel Containing a Beta-Cyclodextrin-Curcumin Inclusion Complex Improves Wound Healing In Vivo.

Scarless wound healing is ideal for patients suffering from soft tissue defects. In this study, we prepared a novel wet dressing (ß-CD-ic-CUR/GC) based on the visible light-cured glycol chitosan (GC) hydrogel and inclusion complex between beta-cyclodextrin (ß-CD) and curcumin (CUR). We also evaluated its efficacy in the acceleration of wound healing as compared to that of CUR-loaded GC (CUR/GC). The conjugation of glycidyl methacrylate (GM) to GC for photo-curing was confirmed by ¹H-NMR measurement, and the photo-cured GC hydrogel was characterized by the analyses of rheology, swelling ratio, SEM and degradation rate. After visible light irradiation, the surface/cross-sectional morphologies and storage (G')/loss (G'') moduli revealed the formation of hydrogel with interconnected porosity. The dressing ß-CD-ic-CUR/GC exhibited a controlled release of 90% CUR in a sustained manner for 30 days. On the other hand, CUR/GC showed CUR release of 16%. ß-CD acted as an excipient in improving the water-solubility of CUR and affected the release behavior of CUR. The in vivo animal tests including measurement of the remaining unhealed wound area and histological analyses showed that ß-CD-ic-CUR/GC may have potential as a wet dressing agent to enhance soft tissue recovery in open fractures.

In Vitro Osteogenic Differentiation Enhanced by Zirconia Coated with Nano-Layered Growth and Differentiation Factor-5.

Zirconia (Zr) is also known as a biocompatible material with favorable mechanical properties as well as low plaque adhesion. In this study, we examined the efficacy of Zr coated with growth and differentiation factor-5 (GDF-5) bonded via click reaction as a substrate to support osteogenic differentiation of MC3T3-E1 cells. Pristine and surface-modified Zr surfaces were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), resulting that GDF-5 was successfully coated to the pristine Zr surface. GDF-5 coated to Zr surfaces was released for 28 days in a sustained manner. New bone formation onto GDF-5 coated Zr (Zr/GDF-5) surface was confirmed by in vitro test including cell proliferation, alkaline phosphatase activity and calcium deposition assays, and in vivo test including real-time polymerase chain reaction (qPCR) assay including osterix (OSX), runt-related transcription factor 2 (Runx 2), COL 1 (type I collagen) and osteocalcin (OC). Cell proliferation, alkaline phosphatase activity, and calcium deposition of MC3T3- E1 cells were significantly enhanced when the cells were cultured on Zr/GDF-5. Additionally, the results of qPCR revealed that genes related with osteogenic differentiation were up regulated when the cells were cultured on Zr/GDF-5. Our findings demonstrate that Zr/GDF-5 could be used as a material for enhancing the efficacy of osteogenic differentiation.

Sedation Protocol Using Dexmedetomidine for Third Molar Extraction.

PURPOSE: The aim of this study was to establish a proper sedative protocol of dexmedetomidine for outpatients. MATERIALS AND METHODS: The study compared compare patients' pain, satisfaction, adverse events, and sedation depth during extraction of third molars using a sedative protocol of intravenous (IV; 1.0 µg/kg) versus intranasal (IN; 1.5 µg/kg) administration of dexmedetomidine. In total, 240 patients were randomized, 160 patients received dexmedetomidine, and data, including the amount of agent used, visual analog scale (VAS) pain score, adverse events, VAS score of patient satisfaction, and bispectral index, were recorded. RESULTS: Patients in the dexmedetomidine groups reported lower VAS pain scores and higher VAS satisfaction scores than patients in the local anesthesia group. There were no statistically meaningful differences between dexmedetomidine groups. Sedation with the IV route was slightly deeper than with the IN route. However, there were no statistically meaningful differences. CONCLUSION: IN or IV administration of dexmedetomidine is recommended as an effective, safe, and competent protocol in outpatient sedative surgeries.

Expression of thymosin beta-4 in human periodontal ligament cells and mouse periodontal tissue and its role in osteoblastic/cementoblastic differentiation.

A recent report showed that thymosin beta-4 (Tß4) is expressed during the development of tooth germ, but its effect on osteoblastic/cementoblastic differentiation is a controversial topic. Furthermore, the precise expression and function of Tß4 in periodontal tissue remains unclear. Therefore, the purpose of this study was to investigate the immunolocalization of Tß4 in the developing periodontium of mouse, the function of Tß4 in osteoblastic/cementoblastic differentiation, and the underlying mechanism regulating periodontal regeneration in human periodontal ligament cells (hPDLCs), cementoblasts, and osteoblasts. Tß4 expression was observed in differentiating hPDLCs, osteoblasts of the periodontium during development, as well as in mature tissue. Higher Tß4 expression was observed in hPDLCs than in cementoblasts and osteoblasts in the developing periodontium. The expression of Tß4 mRNA and protein gradually increased during PDL cell differentiation. The downregulation of Tß4 expression by Tß4 siRNA transfection inhibited osteoblastic differentiation by decreasing calcium nodule formation, alkaline phosphatase (ALP) activity, and mRNA expression of differentiation markers in hPDLCs, cementoblasts, and osteoblasts. In contrast, Tß4 activation using a Tß4 peptide, promoted these processes by activation of Akt, p38, ERK MAPKs, and the NF-κB pathway. The expression of nuclear NFATc1 was upregulated by Tß4 peptide in hPDLCs. Inhibition of the calcineurin/NFATc1 pathway by cyclosporin A and FK506, attenuated Tß4-induced osteoblastic differentiation and activation of Wnt-related genes, as well as nuclear ß-catenin in hPDLCs. In conclusion, this study demonstrates, for the first time, that Tß4 is expressed in developing periodontal tissue and that its expression is associated with osteoblastic/cementoblastic differentiation. These results suggests that Tß4 is a potential therapeutic target for periodontal regeneration or bone disease.

Combined effects of mineral trioxide aggregate and human placental extract on rat pulp tissue and growth, differentiation and angiogenesis in human dental pulp cells.

OBJECTIVE: The aim of this study was to evaluate the combined effects of mineral trioxide aggregate (MTA) and human placental extract (HPE) on cell growth, differentiation and in vitro angiogenesis of human dental pulp cells (HDPCs) and to identify underlying signal transduction mechanisms. In vivo dental pulp responses in rats for a pulp-capping agent were examined. MATERIALS AND METHODS: MTS assay. ALP activity test, alizarin red S staining and RT-PCR for marker genes were carried out to evaluate cell growth and differentiation. HUVEC migration, mRNA expression and capillary tube formation were measured to evaluate angiogenesis. Signal transduction was analysed using Western blotting and confocal microscopy. The pulps of rat maxillary first molars were exposed and capped with either MTA or MTA plus HPE. Histologic observation and scoring were performed. RESULTS: Compared to treatment of HDPCs with either HPE or MTA alone, the combination of HPE and MTA increased cell growth, ALP activity, mineralized nodules and expression of marker mRNAs. Combination HPE and MTA increased migration, capillary tube formation and angiogenic gene expression compared with MTA alone. Activation of Akt, mammalian target of rapamycin (mTOR), p38, JNK and ERK MAPK, Akt, and NF-κB were significantly increased by combining HPE and MTA compared with MTA alone. Pulp capping with MTA plus HPE in rats showed superior dentin bridge formation, odontoblastic layers and dentinal tubules and lower inflammatory cell response, compared to the MTA alone group. CONCLUSIONS: This study demonstrates for the first time that the use of MTA with HPE promotes cell growth, differentiation and angiogenesis in HDPCs, which were associated with mTOR, MAPK and NF-κB pathways. Direct pulp capping with HPE plus MTA showed superior results when compared with MTA alone. Thus, the combination of MTA and HPE may be useful for regenerative endodontics.

Salvage of the condylar fracture: complication management of mandibular angle ostectomy.

A prominent mandibular angle is considered to be unattractive in Asians because it gives the face a square, coarse, and muscular appearance. Mandibular angle ostectomy has been known to be effective and to satisfy both surgeons and patients. However, a narrow surgical field hinders direct view of the site, making a procedure that is rather difficult to perform. Despite thorough presurgical planning and attention, there can be many complications and unfavorable results. A 21-year-old woman with right condyle process fracture was referred to Kyung Hee University Hospital at Gangdong. The patient was previously treated with mandibular angle reduction surgery at a local clinic. Via an extraoral approach, the condyle process was replaced and fixed using 1 long metal screw and one 2 × 2 square metal plate. We overcame the condylar fracture caused by mandibular angle ostectomy with reasonable reduction of the right condyle.

Quick and accurate measures in negative pressure pulmonary edema: a guideline for orthognathic surgeons.

Perioperative pulmonary edema is a rare complication of maxillofacial surgery. However, this potentially fatal complication may arise during any maxillofacial surgery. Negative pressure pulmonary edema can be caused by upper airway obstruction after operation. When this phenomenon arises, if not treated properly, it progresses rapidly causing fatal outcomes. Because orthognathic surgery is performed mostly on healthy and young patients, surgeons and anesthesiologists might neglect the possibility of such complications. Therefore, we must always take into consideration the possibility of negative pressure pulmonary edema. Careful observation of the patient; accurate knowledge; and active, quick, and noninvasive safe measures are required to treat this malady when it does occur. We report a case of negative pressure pulmonary edema after orthognathic surgery and its successful treatment.

Arch coordination does not affect the stability in class III orthognathic surgery patients.

The purpose of this study was to evaluate if the arch coordination manifested by preorthodontics had an effect on the short-term stability after orthognathic surgery by evaluating the B point, menton, overjet, and overbite. The subjects were 10 healthy adult female and male Koreans (mean age, 24.9 years) with insufficient arch coordination and 10 healthy adult female and male Koreans (mean age, 22 years) with sufficient arch coordination. All subjects had sagittal split ramus osteotomy with 1-piece maxillary Le Fort I surgery with/without genioplasty done from the same practitioner at Kyung Hee University Hospital at Gangdong from 2009 to 2011. All arch widths of the maxilla and mandible were measured. Cephalometric tracings of the subjects were made of the presurgical and postsurgical period with a follow-up at 3 months. Relapse was measured according to cephalometric tracing changes using the V-ceph Cephalometric Analysis Software version 5.5(Osstem, Seoul, South Korea). Insufficient arch coordination did not definitively affect the overall treatment outcome. There was significant difference in the horizontal dimensions of the mandible (vertical plane to point B, overjet) in the study group. The study group showed instability in orthodontic factors, whereas skeletal factors were stable. Vertical dimensions (horizontal plane to point B, horizontal plane to menton, overbite) were not statistically significant.

Minimal invasive and cost-effective method in reduction of maxillofacial fracture by using a Foley catheter ballooning technique.

The purpose of this study was to introduce 2 successful cases of orbital inferior wall fracture and maxillary sinus anterior wall fracture using the Foley catheter ballooning technique. One patient is a 43-year-old man with left orbital inferior wall fracture. A window on the sinus was made for visualization, and a Foley catheter was accessed through the natural ostium. The ballooned catheter was inflated to lift the inferior orbital wall rim and stationed for 2 weeks. The window was closed using metal plates and screws. Another patient is a 64-year-old woman with right maxillary sinus anterior wall fracture, nasal fracture, and orbital blow-out fracture. A Foley catheter was accessed through the fractured maxillary sinus and reduced into place and fixed with absorbable plates screws. The technique of stabilization of reduced maxillofacial fractures using a Foley balloon catheter with restorable plates and titanium plates showed stable results. This technique is relatively easy to undergo with minimal or no complications because of reduced operation time. Also, it is cost-effective compared with other materials providing similar results and heightens patient satisfaction.

Local delivery of alendronate eluting chitosan scaffold can effectively increase osteoblast functions and inhibit osteoclast differentiation.

The aim of this study was to investigate the effect of alendronate released from chitosan scaffolds on enhancement of osteoblast functions and inhibition of osteoclast differentiation in vitro. The surface and cell morphologies of chitosan scaffolds and alendronate-loaded chitosan scaffolds were characterized by variable pressure field emission scanning electron microscope (VP-FE-SEM). Alendronate was released in a sustained manner. For evaluating osteoblast functions in MG-63 cells, we investigated cell proliferation, alkaline phosphatase (ALP) activity, and calcium deposition. Furthermore, for evaluating inhibition of osteoclast differentiation in RAW 264.7 cells, we investigated tartrate-resistant acid phosphatase (TRAP) activity, TRAP staining, and gene expressions. The in vitro studies revealed that osteoblasts grown on alendronate-loaded chitosan scaffold showed a significant increment in cell proliferation, ALP activity, and calcium deposition as compared to those grown on chitosan scaffolds. In addition, the in vitro study showed that osteoclast differentiation in RAW 264.7 cells cultured on alendronate-loaded chitosan scaffolds was greatly inhibited as compared to those cultured on chitosan scaffolds by the results of TRAP activity, TRAP staining, and gene expressions. Taken together, alendronate-loaded chitosan scaffolds could achieve the dual functions of improvement in osteoblast functions and inhibition of osteoclast differentiation. Thus, alendronate-eluting chitosan substrates are promising materials for enhancing osteoblast functions and inhibiting osteoclast differentiation in orthopedic and dental fields.

Salvation for hardware failure of resorbable fixation plates in bilateral mandibular angle fractures.

The resorbable fixation system is used for the treatment of facial bone fractures and has many merits. It does not require a fixture removal procedure and is biologically nontoxic. Also, it does not disturb normal growth in growing children. However, there are also many points to be considered, such as resorption time, foreign body reaction, infection rate, or fixation stability depending on the fracture pattern. Because of these factors, there is still controversy over the use of a resorbable system.We present a case of a patient who experienced malunion after using a resorbable fixation system to treat bilateral mandibular angle fracture, which was recovered by corrective osteotomy and vertical ramus osteotomy in our department.