• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.405-417
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• 2010

Previous studies have already shown that mouthguard is effective in protecting jaw bone, teeth and oral tissue against sports trauma. However, other than severe trauma, repetitive force, such as disorders like clenching, cause teeth or oral tissue damage. These kinds of disorders usually present pathologic attrition in the posterior teeth, resorption in alveolar bone, loss of teeth and destruction of occlusion. Wearing a mouthguard is believed to be effective in preventing these disorders. But its effect is not examined thoroughly enough. The purpose of this study is to identify whether mouthguard is effective in reducing strain caused by clenching. Mandibular first molars in the normal occlusal relationship without any history of dental treatment were chosen. Biaxial type strain gauge was placed on the buccal surface of the tooth. Having maximum occlusal force, measured by load cell, as a standard, clenching intensity were divided into three stages; moment of slightly tooth contact, medium bite force (50% of maximum bite force), maximum bite force. Strain occurring in dentition in each stage with and without mouthguard was measured. Changes in strain (on dentition) between each stage and difference in strain, between with or without mouthguard were recorded by PCD-300 analyzer and PCD-30 soft ware. The data was statistically analyzed by Wilcoxon signed rank test. The following results were drawn; Without mouthguard, strain given on dentition increased as the clenching force increased. With mouthguard, strain given on dentition also increased as the clenching force increased. With mouthguard, strain decreased, in all cases of clenching force stages. Data on the moment of slightly tooth contact stage, had no statistical significance. However, with mouthguard, 50-90% of decrease in strain could be obtained in maximum occlusal force, compared to the group without mouthguard. Mouthguard decreased the strain on the dentition, caused by clenching. Therefore, mouthguard seems to be effective in preventing damage on dentition, by acting against clenching, which occurs both consciously and unconsciously during sports activities.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.6
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• pp.720-731
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• 2003

Statement of problem. The importance of fixture design and surface treatment. Purpose. The clinical success of dental in plants is affected by many factors such like as degree of osseointegration, the effective load dispersion for the prostheses, and a lot of attempts have been made to overcome the difficulties. In this study, efforts were made to find the possibility of clinical acceptance of the dental implants of newly designed surface and resorbable blast media surcace. Materials and methods. In this study, two groups of custom-made, screw-shaped implants were prepared. The first with the consisting of Branemark clone design and the other with the new design. These implants were divided into four groups according to the kinds of surface treatment. Four implants($AVANA^{(R)}$, Osstem, Busan, Korea)of each group were installed in twenty rabbits. Group A was consisted of Branemark done implant left as machined, Group B with Branemark clone implants with RBM(Resorbable blast media) surface, Group C with newly designed implants left as machined and Group D with newly designed implants with RBM surface. One of the twenty rabbits died from inflammation and the observation was made for six weeks. Specimens from four groups were observed using scanning electron microscopy with 40, 100, 1000 magnification power and microsurface structures were measured by white-light scanning interferometry for three dimensional surface roughness measurements(Accura $2000^{(R)}$, Intek-Plus, Korea.). Removal torque was measured in 17 rabbits using digital torque gauge(MGT 12R, Mark-10 corp., NY, U.S.A.) immediately after the sacrifice and two rabbits were used for the histologic preparation(EXAKT $310^{(R)}$, Heraeus Kulzer, wehrheim, Germany) of specimens and observed under light microscope. Resonance frequency measurement($Osstell^{(R)}$) was taken with the 19 rabbits at the beginning of the implant fixation and immediately after the sacrifice. Results. Following results were taken from the experiment. 1. The surface of the RBM implants as seen with SEM had rough and irregular pattern with reticular formation compared to that of fumed specimens showing different surface topographies. 2. The newly designed implant with RBM surface had high removal torque value among four groups with no statistical significance. The average removal torque was $49.95{\pm}6.70Ncm$ in Group A, $51.15{\pm}4.40Ncm$ in Group B, $50.78{\pm}9.37Ncm$ in Group C, $51.09{\pm}4.69Ncm$ in Group D. 3. The RFA values were $70.8{\pm}4.3Hz$ in Group A, $71.8{\pm}3.1Hz$ in Group B, $70.9{\pm}2.5Hz$, $72.7{\pm}2.5Hz$ in Group D. Higher values were noted in the groups which had surface treatment compared to the untreated groups with no statistical significance. 4. The results from the histomorphometric evaluation showed a mean percentage of bone-to-implant contact of $45{\pm}0.5%$ in Group A, $55{\pm}3%$ in Group B, $49.5{\pm}0.5%$ in Group C, and $55{\pm}3%$ in Group D. Quite amount of newly formed bone were observed at the surface RBM-treated implants in bone marrow space.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.77-77
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• 2003

Coculture of HSC with bone marrow-derived mesenchymal stem cells (BM-MSCs) is one of used methods to increase cell numbers before transplant to the patients. However, because of difficulties to purify HSCs after coculture with BM-MSCs, it needs to develop a method to overcome the problem. In the present study, we have examined whether a culture insert placed over a feeder layer might support the expansion of HSCs within the insert. $CD34^+/ $ cells isolated from the umbilical cord blood by using midiMACS were divided into three groups. A group of 1 $\times$ $10^5$ cells were grown on a culture insert without feeder layer (Direct). The same number of HSCs was directly cocultured with BM-MSCs (Contact). The third group was placed onto an insert below which BM-MSCs were grown (Insert). To distinguish feeder cells from HSCs, BM-MSCs was pre-labeled fluorescently with PKH26 and 1 $\times$ $10^5$ cells were seeded in the culture dishes. After culture for 13 days, the expansion factor (x) of HSCs that were grown without feeder layer (Direct) was $26.6 \pm 8.4.$ In contrast, the number of HSCs directly cocultured with feeder layer was 59.6 $\pm$ 0.5 and that of HSCs cultured onto an insert was $46.9 \pm 8.4.$ The percentage of BM-MSCs cells remained being fluorescent was $97.9 \pm 0.3%$ after culture. Immune-phenotypically large proportion of cultured cells were founded to be differentiated into myeloid/monocyte progenitor cells. The ability of BM-MSCs, fetal lung, cartilage and brain tissue cells to support ex vivo expansion of HSCs was also examined using the insert. After 11 days of coculture with each of these cells, the expansion factor of HSCs was 15.0, 39.0, 32.0 and 24.0, respectively. Based upon these observations, it is concluded that the coculture method using insert is very effective to support ex vivo expansion of HSCs and to eliminate the contamination of other cells used to coculture wth HSCs.

• The korean journal of orthodontics
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• v.38 no.5
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• pp.328-336
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• 2008

Objective: The purpose of this study was to compare the torque resistance to removal of sandblasted large grit and acid etched (SLA) surface treated orthodontic mini-implants and smooth surface orthodontic mini-implants as well as performing histologic observations. Methods: Two groups of custom screw shaped orthodontic mini-implants (C-implant, 1.8 mm outer diameter $\times$ 9.5 mm length, Cimplant, Seoul, Korea) were designated. 22 SLA treated C-implants (SLA group) and 22 machined surface C-implants (machined group) were placed in the tibia metaphysis of 11 adult New Zealand white rabbits. Following a 6-week healing period, the rabbits were sacrificed. Subsequently, the C-implants were removed under reverse torque rotation with a digital torque measuring device and independent t-test was performed. Selected tissues were prepared for histologic observation. Results: The SLA group presented a higher mean removal torque value (6.286 Ncm) than the machined group (4.491 Ncm) which was statistically significant (p < 0.005). Histologic observation revealed a trend of more new bone formation in contact with the screw surface in the SLA group than the smooth group. Conclusions: The results of this study suggested that SLA surface treatment can enhance the osseintegration potential for C-orthodontic mini-implants.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.6
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• pp.460-465
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• 2010

Introduction: A cleft palate is a common birth defect in humans with an incidence of 1/500 to 1/1,000 births. It appears to be caused by multiple genetic and environmental factors during palatogenesis. Many molecules are involved in palate formation but the biological mechanisms underlying the normal palate formation and cleft palate are unclear. Accumulating evidence suggests that transforming growth factor $\beta$/bone morphogenetic proteins (TGF-$\beta$/BMP) family members mediate the epithelial-mesenchymal interactions during palate formation. However, their roles in palatal morphogenesis are not completely understood. Materials and Methods: To understand the roles of TGF-$\beta$/BMP signaling in vivo during palatogenesis, mice with a palatal mesenchyme- specific deletion of Smad4, a key intracellular mediator of TGF-$\beta$/BMP signaling, were generated and analyzed using the Osr2Ires-Cre mice. Results: The mutant mice were alive at the time of birth with open eyelids and complete cleft palate but died within 24 hours after birth. In skeletal preparation, the horizontal processes of the palatine bones in mutants were not formed and resulted in a complete cleft palate. At E13.5, the palatal shelves of the mutants were growing as normally as those of theirwild type littermates. However, the palatal shelves of the mutants were not elevated at E14.5 in contrast to the elevated palatal shelves of the wild type mice. At E15.5, the palatal shelves of the mutants were elevated over the tongue but did not come in contact with each other, resulting in a cleft palate. Conclusion: These results suggest that mesenchymal Smad4 mediated signaling is essential for the growth of palatal processes and suggests that TGF-$\beta$/BMP family members are essential regulators during palate development.

• Polymer(Korea)
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• v.36 no.3
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• pp.357-363
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• 2012

Surface-modified poly(L-lactic acid) (PLLA) films and scaffolds were treated with plasma discharge in oxygen gas and subsequently subjected to $in$ $situ$ grafting of acrylic acid (AA) in order to increase the cell compatibility. The surface of AA-grafted PLLA was converted to hydroxyapatite (HA)-deposited PLLA in stimulated body fluid (SBF). After the samples were immersed in phosphate-buffered saline (PBS), fetal bovine serum (FBS), normal saline, or cell medium, the water contact angles were significantly reduced on the surface of HA-deposited PLLA. Chondrocyte and osteoblast showed a higher attachment and cell proliferation on HA-deposited surfaces and in particular, it was confirmed that chondrocyte was considerably influenced by HA. However, osteoblast showed better cell proliferation on the surfaces immersed in FBS, cell medium or HA-deposited surface. In addition, the cell proliferation in 3D scaffolds was much higher than that on film type, irrespective of chondrocyte and osteoblast. Therefore, such surface-modified PLLAs are expected to be useful as organic-inorganic hybrid scaffolds in the regeneration of cartilage and bone.

• The korean journal of orthodontics
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• v.23 no.1 s.40
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• pp.1-15
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• 1993

This study was undertaken to investigate the midline having the least difference between the right and left structures among the lines that had been used in the study of the craniomaxillofacial asymmetry. The sample of this study consisted of twenty six Korean girls(average 18.9 years old) having normal facial appearance and occlusion. On the frontal cephalometric films of the sample, we divided the whole craniomaxillofacial area into four portions, i.e., cranial, upper facial, lower facial, and dental portion. So, we have found the midlines having the least difference in the whole craniomaxillofacial area itself, and in the each divided four portions, furtherly in the other portions from aimed portion. The findings were as follow: 1. In the whole craniomaxillofacial area, the connecting line between crista galli and anterior nasal spine and the perpendicular bisecting line between right and left foramen rotundums were suitable for the midline. 2. In the cranial portion, established all six lines were suitable for midlines. In the other portions, the perpendicular bisection line between both condylion, the line passing the contact point between right and left mandibular central insisiors among the perpendicular lines between right and left mandibular central incisial tips were suitable midlines fer evaluating the asymmetry of cranial portion. 3. In the upper facial portion, the perpendicular bisecting line between right and left zygions was the most suitable midline. In the other portions, the line between the crista galli and the most superior point of the odontoid process, the perpendicular bisecting line between right and left gonions, the perpendicular bisecting line between right and left condylions, and perpendicular bisecting line between right and left foramens rotundum were suitable midlines for evaluating the asymmetry of the upper facial portion 4. In the dental portion, the perpendicular bisecting lines between right and left buccal cusps of both maxillary first molars and between right and left mandibular first molars were suitable midlines. In the other portions, the perpendicular bisecting line between right and left landmarks crossing the lesser wing of the sphenoid bone and orbit, the perpendicular bisecting line between right and left mental foramens, and the connecting line between crista galli and prosthion were suitable midlines for evaluating the asymmetry of dental portion. 5. In the lower facial portion, the perpendicular bisecting lines between right and left condylions and between right and left gonions were suitable midlines. In the other portions, the line between the crista galli and anterior nasal spine, the perpendicular bisecting line between right and left foramen rotundums, and the perpendicular bisecting lines between right and left buccal cusps of both mandibular first molars and between right and left maxillary first molars were suitable midlines for evaluating the asymmetry of the lower facial portion.

• Journal of the Korean Arthroscopy Society
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• v.4 no.1
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• pp.54-60
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• 2000

Purpose : The purpose of this study was to evaluate the gutter pathologies and the clinical results of arthroscopic treatment for ankle gutter syndrome. Materials and Methods : Seventy six patients(77 ankles) who had lesions in the ankle gutter were treated by arthroscopy. The gutter pathology could be divided into 3 categories; hypertrophic scar tissue, loose bodies and bone spurs. Fifty two patients were evaluated subjectively and functionally with authors' criteria. The follow-up period averaged 44 months(range, 2.9 year-8.5 year). Results : The incidence of the gutter lesion was $21\%$(77 ankles) among 366 ankles undergoing arthroscopy. The most common pathology was hypertrophic scar tissue. In 31 ankles$(40\%)$, the lesions were found only in gutter, and 46 ankles$(60\%)$ were associated with pathologies in other areas. All of parameters for subjective and functional evaluation were improved with statistical significance(p<0.001). Seventeen patients$(33\%)$ could returned to competitive or contact sports activity with same level of premorbid period. Conclusion : Ankle gutter is an important site of pathologies which cause chronic ankle pain, and should be explored in ankle arthroscopy. The ankle arthroscopy is a very effective treatment method fur the removal of pathologies in ankle gutter syndrome.

• IMMUNE NETWORK
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• v.3 no.3
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• pp.188-200
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• 2003

Background: Immunization of dendritic cells (DCs) pulsed with tumor antigen can activate tumor-specific cytotoxic T lymphocytes (CTL) that are responsible for protection and regression. In this study, we examined whether the uptake of necrotic tumor cells could modulate DC phenotypes and whether the immunization of necrotic tumor cell-loaded DCs could elicit efficient tumor specific immune responses followed by a regression of established tumor burdens. Methods: We prepared necrotic tumor cell-pulsed DCs for the therapeutic vaccination and investigated their phenotypic characteristics, the immune responses induced by these DCs, and therapeutic vaccine efficacy against colon carcinoma in vivo. Several parameters including phagocytosis of tumor cells, surface antigen expression, chemokine receptor expression, IL-12 production, and NK as well as CTL activation were assessed to characterize the immune response. Results: DCs derived from mouse bone marrow efficiently phagocytosed necrotic tumor cells and after the uptake, they produced remarkably increased levels of IL-12. A decreased CCR1 and increased CCR7 expression on DCs was also observed after the tumor uptake, suggesting that antigen uptake could induce DC maturation. Furthermore, co-culturing of DCs with NK cells in vitro enhanced IL-12 production in DCs and IFN-${\gamma}$ production in NK cells, which was significantly dependent on IL-12 production and cell-to-cell contact. Immunization of necrotic tumor cell-loaded DCs induced cytotoxic T lymphocytes as well as NK activation, and protected mice against subsequent tumor challenge. In addition, intratumoral or contra-lateral immunization of these DCs not only inhibited the growth of established tumors, but also eradicated tumors in more than 60% of tumor-bearing mice. Conclusion: Our data indicate that production of IL-12, chemokine receptor expression and NK as well as CTL activation may serve as major parameters in assessing the effect of tumor cell-pulsed DC vaccine. Therefore, DCs loaded with necrotic tumor cells offer a rational strategy to treat tumors and eventually lead to prolonged survival.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.4
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• pp.352-358
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• 2011

Purpose: This study evaluated the prognosis and survival rate of SLA (Sandblasted, Large-grit and Acid-etched) implants and it also evaluated the prosthodontic complications and the associated factors. Methods: Twenty seven patients (14 men and 13 women, mean age: 54.9) who visited Chosun University Hospital Implant Center with the chief desire for placement of an implant in an edentulous area from March, 2008 to December 2008 and who received placement of a SLA implant ($Implantium^{(R)}$, Dentium Co., Korea) were selected for this study. Results: The average follow-up period was 15 months and the study was based on the treatment records, radiographs and clinical examinations. A total of 69 implant cases were retrospectively assessed for the width and length of the implant, the primary and secondary stability, the combined surgery, the employed bone graft material and barrier membrane, the status of the opposing tooth, implant failure and the prosthetic complications. During the follow-up period (average: 15 months), the accumulative survival rate of the 69 implants in 27 patients was 100%. Complications such as infection, sinusitis and fixture exposure after surgery were seen for 5 implants in 4 patients. Complications such as screw loosening, contact loosening and peri-implant gingivitis after prosthodontic treatment occurred in 7 cases (10.14%). Conclusion: This study reports placement of SLA implants may cause various complications, yet the final accumulative survival rate was 100%. The SLA implant ($Implantium^{(R)}$) has an excellent clinical survival rate and outcome.