Min-Suk Kook

Evaluation of a Thiolated Chitosan Scaffold for Local Delivery of BMP-2 for Osteogenic Differentiation and Ectopic Bone Formation

Thiolated chitosan (Thio-CS) is a well-established pharmaceutical excipient for drug delivery. However, its use as a scaffold for bone formation has not been investigated. The aim of this study was to evaluate the potential of Thio-CS in bone morphogenetic protein-2 (BMP-2) delivery and bone formation. In vitro study showed that BMP-2 interacted with the Thio-CS and did not affect the swelling behavior. The release kinetics of BMP-2 from the Thio-CS was slightly delayed (70%) within 7 days compared with that from collagen gel (Col-gel, 85%), which is widely used in BMP-2 delivery. The BMP-2 released from Thio-CS increased osteoblastic cell differentiation but did not show any cytotoxicity until 21 days. Analysis of the in vivo ectopic bone formation at 4 weeks of posttransplantation showed that use of Thio-CS for BMP-2 delivery induced more bone formation to a greater extent (1.8 fold) than that of Col-gel. However, bone mineral density in both bones was equivalent, regardless of Thio-CS or Col-gel carrier. Taken together, Thio-CS system might be useful for delivering osteogenic protein BMP-2 and present a promising bone regeneration strategy.

Bisphosphonates-related osteonecrosis of the jaw in Korea: a preliminary report

Objectives Bisphosphonates (BP) are widely used in medicine for inhibiting bone resorption; however bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a major side effect of BP. To date, there have been no specific reports on the incidence of BRONJ among Koreans. This study investigated the preliminary results from a nationwide survey of BRONJ in the Departments of Oral and Maxillofacial Surgery (OMFS) at individual training hospitals. Materials and Methods A total of 15 OMFS departments (10 from dental schools, 4 from medical schools, and 1 from a dental hospital) participated in a multi-centric survey. This study assessed every BRONJ case diagnosed between January 2010 and December 2010. The patient age and BP type were evaluated. Results A total of 254 BRONJ cases were collected. The majority of BRONJ cases were associated with oral BP therapy, while 21.8% of the cases were associated with intravenous administration. Alendronate was the drug most frequently related to BRONJ (59.2% of cases), followed by risedronate (14.3%) and zolendronate (17.0%). The average age of BRONJ patients was 70.0±10.1 years, with a range of 38-88 years of age. With the number of BP patients in Korea reported to be around 600,000 in 2008, the estimated incidence of BRONJ is at least 0.04% or 1 per 2,300 BP patients. Conclusion The results suggest that the estimated incidence of BRONJ in Korea is higher than the incidence of other countries. Future prospective studies should be carried out to investigate the exact epidemiological characteristics of BRONJ in Korea.

Reduction Malarplasty Using Modified L-Shaped Osteotomy

t m Zygomatic bone, which protrudes on both sides of the midface, plays an important role in determining the facial impression. Many esthetic differences regarding the malar prominence exist between Asians and whites. In the West, augmentation malarplasty s performed mainly because a slightly prominent alar is believed to be esthetically pleasing. In ontrast, in the East, a prominent malar is believed o project an aggressive and unpleasing impression, articularly for women. Therefore, many reduction alarplasty procedures have been developed. For eduction malarplasty, bone shaving, infracture, and I-shaped and L-shaped osteotomy methods ave been used. Of these techniques, an I-shaped osteotomy can e used for a moderate or severe malar promience. This is an effective and safe method for educing the anterior zygoma with no damage to he maxillary sinus. This method, however, can esult in insufficient bone reduction ( 5 mm) and isturb the middle 0.333 of the zygoma (the most rominent area). An L-shaped osteotomy can be used for severe malar protrusion. The fracture line

Peroxiredoxin V selectively regulates IL-6 production by modulating the Jak2–Stat5 pathway

Mammalian peroxiredoxin V (PrdxV) is a multifunctional protein that protects cells from DNA damage and inhibits stress-induced apoptosis. However, PrdxV is also known to be involved in modulating lipopolysaccharide (LPS)-induced host cell signaling, but its precise role is not fully understood. In this study, we used stably transfected RAW264.7 cells and transiently transfected 293-mTLR4-MD2-CD14 cells expressing wild-type (WT) or mutant (C48S) PrdxV to characterize the function and mechanism of action of PrdxV in LPS-induced immune responses. We found that PrdxV selectively reduces production of interleukin 6 (IL-6) by inhibiting activation of signal transducer and activator of transcription 5 (Stat5) through interaction with Jak2. Notably, this activity of PrdxV was dependent on its catalytic Cys48 residue, but not its peroxidase activity. The binding of to Jak2 effectively inhibited Jak2 phosphorylation, but PrdxV did not act as efficiently as SOCS1 (suppressor of cytokine signaling 1). Our results suggest that PrdxV is a key mediator contributing to the regulation of LPS/TLR4-induced immune responses.

NOX1/2 activation in human gingival fibroblasts by Fusobacterium nucleatum facilitates attachment of Porphyromonas gingivalis

Periodontal diseases are infectious polymicrobial inflammatory diseases that lead to destruction of the periodontal ligament, gingiva, and alveolar bone. Sequential colonization of a broad range of bacteria, including Fusobacterium nucleatum and Porphyromonas gingivalis, is an important phenomenon in this disease model. F. nucleatum is a facultative anaerobic species thought to be a key mediator of dental plaque maturation due to its extensive coaggregation with other oral bacteria, while P. gingivalis is an obligate anaerobic species that induces gingival inflammation by secreting various virulence factors. The formation of a bacterial complex by these two species is central to the pathogenesis of periodontal disease. Reactive oxygen species (ROS) are produced during bacterial infections and are involved in intracellular signaling. However, the impact of oral bacteria-induced ROS on the ecology of F. nucleatum and P. gingivalis has yet to be clarified. In the present study, we investigated ROS production induced in primary human oral cells by F. nucleatum and P. gingivalis and its effect on the formation of their bacterial complexes and further host cell apoptosis. We found that in primary human gingival fibroblasts (GFs), two NADPH oxidase isoforms, NOX1 and NOX2, were activated in response to F. nucleatum infection but not P. gingivalis infection. Accordingly, increased NADPH oxidase activity and production of superoxide anion were observed in GFs after F. nucleatum infection, but not after P. gingivalis infection. Interestingly, in NOX1, NOX2, or NOX1/NOX2 knockdown cells, the number of P. gingivalis decreased when the cells were coinfected with F. nucleatum. A similar pattern of host cell apoptosis was observed. This implies that F. nucleatum contributes to attachment of P. gingivalis by triggering activation of NADPH oxidase in host cells, which may provide an environment more favorable to strict anaerobic bacteria and have a subsequent effect on apoptosis of host cells.

Odontogenic infection involving the secondary fascial space in diabetic and non-diabetic patients: a clinical comparative study.

OBJECTIVES This retrospective study was performed to evaluate the clinical impact of diabetes mellitus on the prognosis in secondary space infection. MATERIALS AND METHODS Medical records, radiographic images, computed tomography, and microbial studies of 51 patients (25 diabetic patients and 26 non-diabetic patients) were reviewed. Patients were diagnosed as secondary fascial space infections with odontogenic origin and underwent treatment at Chonnam National University Hospital, in Department of Oral and Maxillofacial Surgery, from January 2007 to February 2009. RESULTS COMPARED TO PATIENTS WITHOUT DIABETES, PATIENTS WITH DIABETES WERE PRESENTED WITH THE FOLLOWING CHARACTERISTICS: older age (diabetic patients: 62.9 years, non-diabetic patients, 47.8 years), more spaces involved (diabetic patients, 60%; non-diabetic patients, 27.3%), more intense treatment, longer hospitalization (diabetic patients, 28.9 days; non-diabetic patients, 15.4 days), higher white blood cell and C-reactive protein values, higher incidence of complication (diabetic patients, 40%; non-diabetic patients, 7.7%), and distinctive main causative microorganisms. CONCLUSION These results suggest that the prognosis of diabetic patients is poorer than that of non-diabetic patients in secondary space infections since they had greater incidence rates of involved spaces, abnormal hematologic findings, more complications, and additional procedures, such as tracheostomy.

Vector control of malpositioned segment during alveolar distraction osteogenesis by using rubber traction.

PURPOSE In this study we discuss how to control and maintain the vector of the malpositioned segment, which had occurred in post-distraction, and suggested treatments. PATIENTS AND METHODS We studied a patient who had undergone alveolar distraction osteogenesis and revealed a complication at the end of the distraction period; namely, the malpositioned segment. We treated this patient by removing the screw from the base plate and attaching a wire splint on the adjacent teeth during osseous consolidation as an anchorage to fix the malpositioned segment toward the desired direction. RESULTS At the end of traction application, a normal arch shape was observed. After the completion of distraction, implants were inserted in the ideal position. CONCLUSION The described treatment strategy appears to have good potential for providing an ideal final position of the lingually or palatally inclined bone segment.

Addition of MgO nanoparticles and plasma surface treatment of three-dimensional printed polycaprolactone/hydroxyapatite scaffolds for improving bone regeneration

Magnesium (Mg) plays an important role in the body in mediating cell-extracellular matrix interactions and controlling bone apatite structure and density. Hydroxyapatite (HAp) has been used for osteoconductive bone replacement because of its good compressive strength and biocompatibility. The object of this study is to investigate the effects of adding Magnesium oxide (MgO) nanoparticles to polycaprolactone (PCL)/HAp composites and treating PCL/HAp/MgO scaffolds with oxygen and nitrogen plasma. The 3D PCL/HAp/MgO scaffolds were fabricated using a 3D bioextruder. PCL was mixed with 1-15wt% of MgO and HAp. The scaffolds were treated with oxygen and nitrogen plasma under anisotropic etching conditions to improve the bioactivity. The plasma-treated surfaces were analyzed by X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. In addition, the proliferation and differentiation of pre-osteoblast (MC3T3-E1) cells were examined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and alkaline phosphatase activity. Cell mineralization within the produced scaffolds was analyzed by the quantification of alizarin stainings. The addition of MgO/HAp nanoparticles and plasma treatment enhanced the adhesion, proliferation, and differentiation of MC3T3-E1 cells in the PCL scaffolds. Hence, changes in physical surface morphology and surface chemical properties of the 3D scaffold by plasma treatment can affect the behavior of MC3T3-E1 cells.

Comparative study of the sinus septa between dentulous and edentulous patients by cone beam computed tomography.

Purpose:The purpose of this study was to conduct radiographic comparison of maxillary septa in dentulous and edentulous patients using 3-dimensional cone-beam computed tomography (CBCT). Materials and Methods:From November- 2008 to August 2010, the CBCT of full dentulous 100 patients was conducted randomly at the Department of Radiology, Chonnam National University Dental Hospital. Septa in the maxillary sinus were analyzed. Also, CBCT of 51 patients with partial or full edentulous dentition on maxillary posterior area was obtained. The height of the maxillary sinus septa was measured from the sinus floor, the location divided by the anterior, middle, and posterior portion, and the direction was determined to be the buccopalatal, sagittal, and transverse course. Results:In dentulous patients, sinus septa were found in 27% with 6.01 ± 2.21 mm mean height. The mean age of these patients was 24 years and 9 months, and most septa were found in anterior portion with a buccopalatal course. In cases of edentulous patients, the prevalence of edentulous patients with septa was 25.8% with 5.30 ± 1.90 mm mean height. The mean age of the patients was 63 years and 4 months, and most of septa were in the middle portion with a buccopalatal direction. Conclusion:There was no significant difference in the prevalence, incidence, height, location, and direction of maxillary sinus septa between dentulous and edentulous patients (P > 0.05).

Acute Airway Obstruction Secondary to Lingual Hematoma after Lower Third Molar Extraction: A Case Report

Few dental procedures are potentially life-threatening. Note, however, that a dental extraction can result in preventable death. Severe post-extraction bleeding can occur, which may give rise to an alarming situation if there is any delay in detecting and managing the problem. The most immediate danger for a healthy patient with severe post-extraction hemorrhage is airway compromise. Acute airway obstruction from post-extraction hematoma is relatively uncommon, but it may occur with fatal consequences if there is any reluctance to maintain the airway clearance. Therefore, dentists and oral and maxillofacial surgeons should have clear understanding of the problem and measures to control it. Active bleeding that is not controlled by local measures in a dental office should be referred to the nearest hospital emergency department as soon as possible for appropriate management.