Hyun Seok

Correction of post-traumatic anterior open bite by injection of botulinum toxin type A into the anterior belly of the digastric muscle: case report.

Post-traumatic anterior open bite can occur as a result of broken balance among the masticatory muscles. The superior hyoid muscle group retracts the mandible downward and contributes to the anterior open bite. Denervation of the digastric muscle by injection of botulinum toxin type A (BTX-A) can reduce the power of the digastric muscle and help to resolve the post-traumatic anterior open bite. A patient with a bilateral angle fracture had an anterior open bite even after undergoing three operations under general anesthesia and rubber traction. Although the open bite showed some improvement by the repeated operation, the occlusion was still unstable six weeks after the initial treatment. To eliminate the residual anterior open bite, BTX-A was injected into the anterior belly of the digastric muscle. Following injection of BTX-A, the anterior open bite showed immediate improvement. Complication and relapse were not observed during follow-up. Long-standing post-traumatic open bite could be successfully corrected by injection of BTX-A into the anterior belly of the digastric muscle without complication.

Silk Fibroin-Alginate-Hydroxyapatite Composite Particles in Bone Tissue Engineering Applications In Vivo

The aim of this study was to evaluate the in vivo bone regeneration capability of alginate (AL), AL/hydroxyapatite (HA), and AL/HA/silk fibroin (SF) composites. Forty Sprague Dawley rats were used for the animal experiments. Central calvarial bone (diameter: 8.0 mm) defects were grafted with AL, AL/HA, or AL/HA/SF. New bone formation was evaluated by histomorphometric analysis. To demonstrate the immunocompatibility of each group, the level of tumor necrosis factor (TNF)-α expression was studied by immunohistochemistry (IHC) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) at eight weeks post implantation. Additionally, osteogenic markers, such as fibroblast growth factor (FGF)-23, osteoprotegerin (OPG), and Runt-related transcription factor (Runx2) were evaluated by qPCR or IHC at eight weeks post implantation. The AL/HA/SF group showed significantly higher new bone formation than did the control group (p = 0.044) and the AL group (p = 0.035) at four weeks post implantation. Additionally, the AL/HA/SF group showed lower relative TNF-α mRNA levels and higher FGF-23 mRNA levels than the other groups did at eight weeks post implantation. IHC results demonstrated that the AL/HA/SF group had lower TNF-α expression and higher OPG and Runx2 expression at eight weeks post implantation. Additionally, no evidence of the inflammatory reaction or giant cell formation was observed around the residual graft material. We concluded that the AL/HA/SF composite could be effective as a scaffold for bone tissue engineering.

Topical delivery of 4-hexylresorcinol promotes wound healing via tumor necrosis factor-α suppression

OBJECTIVE The objective of this study was to evaluate (1) the effect of 4-hexylresorcinol (4HR) application on TNF-α expression in RAW264.7 cells and (2) the effect of 4HR ointment on burn wound healing in a rat burn wound model. MATERIALS AND METHODS RAW264.7 cells were cultured in the presence of different concentrations of 4HR, and the attached cells were sampled for western blot analysis at each time point. Animal studies were conducted on male Wistar rats (n=24). Three treatment groups were evaluated in this study: (1) treatment with ointment alone (negative control), (2) treatment with ointment containing 0.2wt% 4HR, and (3) treatment with ointment containing 2wt% 4HR. For the assessment of wound healing, digital photographs were taken at 1, 5, and 14 days. Animals were sacrificed at 1, 5, and 14 days for histological examination or ELISA analysis. RESULTS Western blot analysis showed that TNF-α protein levels were reduced following treatment with 4HR at concentrations between 1 and 10μg/mL. In animal studies, the average denuded area 14 days after burn was smaller in the 2wt% 4HR treatment group compared with the control group (P=0.022). Immunohistochemical analysis revealed lower TNF-α expression in the 2wt% 4HR treatment group compared with the control group 14 days after burn (P=0.027). CONCLUSION 4HR reduced TNF-α expression in RAW264.7 cells and in the burn wounds of rats. Burn wounds dressed with ointment containing 4HR also exhibited rapid epithelization and collagen regeneration.

Comparison of silkworm-cocoon-derived silk membranes of two different thicknesses for guided bone regeneration.

Abstract The objective of this study was to compare the effectiveness of silk membranes (SMs) of different thicknesses for guided bone regeneration. Two kinds of SMs were prepared (SM1: 0.01 mm thickness, SM2: 0.5 mm thickness). Before use in animal experiments, scanning electron microscope images were taken to examine the gross morphology of each membrane. Ten New Zealand white rabbits were used for this study. Bilateral round-shaped defects were created in the parietal bone (diameter: 8.0 mm) and each defect was covered with SM1 or SM2. Animals were killed at 4 weeks and 8 weeks. Bone regeneration was analyzed in each specimen by micro-computed tomography (&mgr;-CT) and histological analysis. In the &mgr;-CT analysis, the average amount of newly formed bone in the SM2 group was greater than that in the SM1 group. There was a significant difference at 4 weeks after surgery (P = 0.004). In the histological analysis, the amount of formed lamellar bone was much greater in the SM2 group than in the SM1 group at 8 weeks after surgery (P = 0.021). In conclusion, the thick SM was much more effective for bone regeneration of bone defects than the thin SM.

In vivo Bone Regeneration Ability of Different Layers of Natural Silk Cocoon Processed Using an Eco-Friendly Method

Silk cocoons are primarily composed of the proteins fibroin and sericin. To achieve guided bone regeneration (GBR), we have developed a simple and ecofriendly processing technique to obtain microperforated thin membranes from cocoons. The separated silk membranes composed of both fibroin and sericin were classified by the cocoon layers (i.e., inner, middle, or outer) from which they originated. This report details the biological properties and the cellular responses of the three silk layers. The different cocoon layers were compared for their bone regeneration capabilities in vivo. The porosity of the silk nets increased from the inner layer to the outer layer when all of the membranes were compared using scanning electron microscopy (SEM). A difference in spectral intensity was observed in the Fourier transform infrared (FT-IR) spectra, indicating different amino acid compositions in these layers. An amino acid composition test demonstrated that the serine content decreased from the outer layer to the inner layer. Characterization of the protein release from each net demonstrated that the highest amount of protein release was observed in the inner layer group. The middle layer showed higher alkaline phosphatase (ALP) activity than the other layers in cellular experiments. Animal experiments indicated that the middle layers exhibit the highest bone volume 8 weeks post-operation (p<0.05). The membranes obtained directly from the thin middle layer of silk cocoons without any regeneration protocol have the potential to be used as an eco-friendly bone regeneration material for in vivo applications.

Reconstruction of partial maxillectomy defect with a buccal fat pad flap and application of 4-hexylresorcinol: a case report

Mucoepidermoid carcinoma (MEC) is the most common type of malignant neoplasm in the minor salivary gland. The hard palate is a frequently involved site of MEC. The treatment of low-grade MEC on the hard palate is wide local resection with a tumor-free margin. In the present case, the maxillary defect was reconstructed using a buccal fat pad (BFP) flap, followed by application of 4-hexylresorcinol (4HR) ointment for 2 weeks. The grafted BFP successfully covered the tumor resection defect without tension and demonstrated complete re-epithelialization without any complications.

Comparison of Different Concentrations of Tetracycline-loaded Silk Fibroin Membranes on the Guided Bone Regeneration in the Rat Calvarial Defect Model

The objective of this study was to evaluate bone regeneration ability using different concentrations of tetracycline (TC) loaded into silk fibroin membranes (SFMs). Prior to animal experiments, MTT assays and alkaline phosphatase (ALP) assays were performed to evaluate the cellular response of each membrane. Critical sized bone defects (8-mm diameter) on rat calvaria were prepared and covered with SFM containing different concentrations of TC:1% TC (TC1), 5% TC (TC5), 10% TC (TC10), and 0% TC (SFM only). The bone regeneration was evaluated by micro-computerized tomography (μ-CT) and histomorphometric analysis at 4 weeks postoperatively. ALP activity was increased in a dose-dependent manner as the applied TC concentrations. By μ-CT analysis, newly formed bone volume in the TC5 group was significantly higher than that in the SFM only group (P<0.001), the TC1 group (P=0.004), and the TC10 group (P=0.012). From histomorphometric analysis, new bone formation was greater in the TC5 group than in the SFM only group (P=0.003) and the TC1 group (P=0.010). There was no significant difference between the TC5 and TC10 group (P>0.05). In conclusion, TC-loaded SFM showed more bone formation than SFM without TC, and the amount of new bone formation was dependent on TC concentrations.

Correction of Malocclusion by Botulinum Neurotoxin Injection into Masticatory Muscles

Botulinum toxin (BTX) is a neurotoxin, and its injection in masticatory muscles induces muscle weakness and paralysis. This paralytic effect of BTX induces growth retardation of the maxillofacial bones, changes in dental eruption and occlusion state, and facial asymmetry. Using masticatory muscle paralysis and its effect via BTX, BTX can be used for the correction of malocclusion after orthognathic surgery and mandible fracture. The paralysis of specific masticatory muscles by BTX injection reduces the tensional force to the mandible and prevents relapse and changes in dental occlusion. BTX injection in the anterior belly of digastric and mylohyoid muscle prevents the open-bite and deep bite of dental occlusion and contributes to mandible stability after orthognathic surgery. The effect of BTX injection in masticatory muscles for maxillofacial bone growth and dental occlusion is reviewed in this article. The clinical application of BTX is also discussed for the correction of dental malocclusion and suppression of post-operative relapse after mandibular surgery.

Postoperative Three-Dimensional Evaluation of Mandibular Contouring Surgery Using Computer-Assisted Simulation Planning and a Three-Dimensional-Printed Surgical Guide.

Mandibular contouring surgery was performed using computer-assisted simulation planning (CASP) and 3-dimensional printed surgical guide. The outcome of the surgery was evaluated by overlapping preoperative image. The patient underwent mandibular contouring surgery according to CASP for his residual facial asymmetry of the mandibular angle and mental area. The overall facial aesthetic of the patient was improved. In the overlapping image, the left mandibular border area was slightly overcorrected. However, the other portion was operated as planned. The overcorrection was due to the improper adaptation of the surgical guide adjacent to the mental foramen. In conclusion, usage of CASP and a surgical guide could reduce operation time and increase the accuracy of the operation. However, the design of the stent should be improved around the mental foramen to avoid nerve damage and improper adaptation.

Migration of Alloplastic Bone Graft Material in Infected Conditions: A Case Study and Animal Experiment

PURPOSE Distant migration associated with sinus lifting procedures has not been investigated. In the present study, a case of distant migration of graft material was observed, and the potential mechanisms of migration were analyzed using material analysis and in vivo experiments. MATERIALS AND METHODS The migrated graft material was biphasic calcium phosphate-based alloplastic material (BCP), and its physical properties were compared with those of xenogenic material (Bio-Oss). The comparisons of the physical properties were performed using scanning electronic microscopic, x-ray diffraction, and Fourier-transform infrared absorbance spectra analysis. The comparative graft migration study was performed using the subcutaneous pocket model in rats (n = 10). The clinical case was analyzed by histologic section and energy dispersive x-ray (EDX) microanalysis. RESULTS The observed diffraction patterns from the Bio-Oss revealed characteristic diffractions for the hydroxyapatite phase, and those from the BCP revealed additional diffractions that could be assigned to the tricalcium phosphate phase. In the animal model, the graft migration distances observed in the BCP group were significantly greater than those observed in the Bio-Oss group (P = .012). In the clinical case, the lymphatic vessels of the submandibular gland contained foreign materials that were morphologically similar to those of the maxillary sinus. EDX microanalysis revealed that the particles in the lymphatic vessels exhibited calcium concentrations that were approximately 200 times greater than those in the adjacent glandular tissue. CONCLUSIONS In the present study, BCP-based sinus grafts had migrated into the submandibular glandular area by way of the lymphatic chain in the presented clinical case.