• Journal of Periodontal and Implant Science
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• v.30 no.2
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• pp.257-277
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• 2000

New techniques for regenerating the destructed periodontal tissue have been studied for many years. Current acceptable methods of promoting periodontal regeneration are basis of removal of diseased soft tissue, root treatment, guided tissue regeneration, graft materials, and biological mediators. Platelet Rich Plasma has been reported as a biological mediator which regulates activities of wound healing progress including cell proliferation, migration, and metabolism. The purpose of this study is to evaluate the effects of using the Platelet Rich Plasma as a regeneration promoting agent for furcation involvement defect. Five adult beagle dogs were used in this experiment. The dogs were anesthetized with Ketamin HCl(0.1 ml/kg, IV)and Xylazine hydrochloride($Rompun^{(R)}$, Bayer, 0.1 ml/kg, IM) and conventional periodontal prophylaxis were performed with ultrasonic scaler and hand instruments. With intrasulcular and crestal incision, mucoperiosteal flap was elevated. Following decortication with 1/2 high speed round bur, degree II furcation defect was made on mandibular third(P3), forth(P4) and fifth(P5) premolar, and stopping was inserted. After 4 weeks, stopping was removed, and bone graft was performed. Ca-P was grafted in P3(experimental group I), Combination of Ca-P and plasma rich platelet were grafted in P4(experimental group II), and P5 was remained at control group.Systemic antibiotics(gentamicin sulfate)and anlgesics(phenyl butazone) were administrated intramuscular for 2 weeks after surgery. Irrigation with 0.1% Chlorhexidine Gluconate around operate sites was performed during the whole experimental period except one day immediate after surgery. Soft diets were fed through the whole experiment period. After 4, 8 weeks, the animals were sacrificed by perfusion technique. Tissue block was excised including the tooth and prepared for light microscope with Gomori's trichrome staining. At 4 weeks after surgery, there were rapid osteogenesis phenomenon on the defected area of the Platelet Rich Plasma plus Ca-P BBP group and early trabeculation pattern was made with new osteoid tissue produced by activated osteoblast. Bone formation was almost completed to the fornix of furcation by 8 weeks after surgery. In conclusion, Platelet Rich Plasma can promote rapid osteogenesis during healing of periodontalregeneration.

• Journal of Periodontal and Implant Science
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• v.32 no.3
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• pp.643-653
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• 2002

Periodontal supporting tissue goes through destruction by chronic inflammatory periodontal disease as two aspect. One is qualitive aspect such as alteration of periodontium, the other is quantitative aspect such as alveolar bone loss. According to many authors, PDL is responsible for biting force, and there are two mean. for measuring PDL's function - mobility test and biting force test. This study was conducted to compare the biting force with remaining bone level, that is, quantitative aspect of periodontium, in anterior and premolar teeth at periodontal maintenance phase. 17 patients on periodontal maintenance phase during 6 months at minimum were selected for this study. For the same condition, 4 anterior, canine, premolar teeth were tested by MPM-3000 bite-force register at the same time(a.m.l0-12), the same position, the same posture, by the same examiner. Patients of TMI), ill-fitting pros thesis, general disease, malocclusion and the teeth of TFO, absence of opposing teeth, malposition were excluded. Remaining bone level was measured on the panorama X-ray film through 5 level from 1mm below CEJ to root apex. Teeth were examined twice, and bigger one was selected. If the values showed large difference. examinatin was re-done and the mean was selected. The results were as follows ; 1. In the 4 anterior group, as the remaining bone is decreased, the average of maximal biting force is decreased. Especially, at 3/5 bone level, maximal biting force is decreased significantly(p<0.01). 2. In the canine group, as the remaining bone is decreased, the average of maximal biting force is decreased. Especially, at 2/5 bone level, maximal biting force is decreased significantly(p<0.01). 3. In the premolar group, as the remaining bone is decreased, the average of maximal biting force is decreased. Especially, at 3/5 bone level, maximal biting force is decreased significantly(p<0.05). From the results of this study, clinicians could utilize these efficiently when they have to determine the proper restorative materials, time for tooth extraction, treatment plan, prognosis.

• Composites Research
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• v.25 no.4
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• pp.98-104
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• 2012

In recent years, degenerative spinal instability has been effectively treated with a cage. However, little attention is focused on the stiffness of the cage. Recent advances in the medical implant industry have resulted in the use of medical carbon fiber reinforced polymer (CFRP) cages. The biomechanical advantages of using different cage material in terms of stability and stresses in bone graft are not fully understood. A previously validated three-dimensional, nonlinear finite element model of an intact L2-L5 segment was modified to simulate posterior interbody fusion cages made of CFRP and titanium at the L4-L5 disc with pedicle screw, to investigate the effect of cage stiffness on the biomechanics of the fused segment in the lumbar region. From the results, it could be found that the use of a CFRP cage would not only reduce stress shielding, but it might also have led to increased bony fusion.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.39 no.6
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• pp.263-268
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• 2013

Objectives: The interforminal region, between the mandibular foramen, is known as a relatively safe area that is free of anatomic structures, such as inferior alveolar nerve, submandibular fossa, and lingual side of the mandible is occasionally neglected for its low clinical importance. Even in the case of a severely constricted alveolus, perforation of the lingual cortical bone had been intended. However, anterior extension of the inferior alveolar canal, important anatomic structure, such as concavity of lingual bone, lingual foramina, and lingual canal, has recently been reported through various studies, and untypical bleeding by perforation of the lingual plate on implantation has also been reported. Therefore, in this study, we performed radiographic and statistical analysis on distribution and appearance frequencies of the lingual foramina that causes perforation of the mandibular lingual cortical bone to prevent complications, such as untypical bleeding, during surgical procedure. Materials and Methods: We measured the horizontal length from a midline of the mandible to the lingual foramina, as well as the horizontal length from the alveolar crest to the lingual foramina and from the lingual foramina to the mandibular border by multi-detector computed tomography of 187 patients, who visited Dankook University Dental Hospital for various reasons from January 1, 2008 to August 31, 2012. Results: From a total of 187 human mandibles, 110 (58.8%) mandibles had lingual foramina; 39 (20.9%) had bilateral lingual foramen; 34 (18.2%) had the only left lingual foramen; and 37 (19.8%) had the only right lingual foramen. Conclusion: When there is consistent bleeding during a surgical procedure, clinicians must consider damages on the branches of the sublingual artery, which penetrate the lingual foramina. Also, when there is a lingual foramina larger than 1 mm in diameter on a pre-implantation computed tomography, clinicians must beware of vessel damage. In order to prevent these complications and progress with a safe surgical procedure, a thorough radiographic examination before the surgery is indispensable. Further, clinicians should retract lingual flap definitely to confirm the shape of the lingual bone and existence of the lingual foramina.

• Journal of Periodontal and Implant Science
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• v.32 no.4
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• pp.769-779
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• 2002

This present study was carried out to find the effects of calcium aluminate cement($CaO\;{\cdot}\;Al_2O_3$, CAC), which has been developed with bio-compatibility and mechanical properties, in biological environments. Two different particle sizes of CAC - 3.5${\mu}m$ vs. 212${\sim}$250${\mu}m$ which is recommended in periodontal bone grafting procedures-were filled in 8mm calvarial defect in Sprague-Dawley rat. The specimens were examined histologically, especially the bone-cement interface and the response of surrounding tissues. The results are as follows; 1. In the control group, inflammatory cells were observed at 2 weeks. At 8 weeks, periosteum and dura mater were continuously joined together in the defect areas. But in the center of defect area were filled up with the loose connective tissues. 2. In the experimental group l($212{\mu}m{\sim}250{\mu}m$ particle), immature bone was formed and outermost layer was surrounded by osteoid layer at 2 weeks. Osteoblasts were arranged between immature bone and osteoid layer. And, osteoid layer was remained until 8 weeks after surgery. 3. In the experimental group 2, periosteum and dura mater lost its continuity at 2 weeks. Scattering of CAC particles and infiltration of inflammatory cells were observed, which this findings deepened at 8 weeks. The result of this study shows that when calvarial defects in white rats are filled with calcium aluminate cement of 212${\sim}$250${\mu}m$, the materials are to be bio-compatible in growth and healing on surrounding tissues. When further researches are fulfilled, such as direct bone adhesion and bone regeneration ability, it's possible that CAC could be applied to various periodontology fields in the future.

• Journal of Periodontal and Implant Science
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• v.28 no.1
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• pp.145-160
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• 1998

The ultimate goal of periodontal therapy is the regeneration of periodontal tissue which has been lost due to destructive periodontal disease, and numerous kinds of materials and techniques have been developed to achieve this goal. Bone grafts include autografts, allografts, xenografts and synthetic grafts. Among the synthetic grafts, bioactive glass has been used in dentistry for more than ten years and Fetner reported improved new bone formation and more amount of new attachment after grafting PerioGlas, a kind of bioactive glass, in 2-wall defects of monkeys in 1994. It Is well known that 1-wall defects have less osteogenic potential and more epithelial migration, so we need to study the erect of bioactive glass in 1-wall dejects in dogs. The present study evaluates the effect of bioactive glass on the epithelial migration, alveolar bone regeneration, cementum formation and gingival connective tissue attachment in intrabony detects of dogs. Four millimeter deep and four millimeter wide 1-wall defects were surgically cheated in the mesial aspects of premolars. The test group received bioactive glass with a flap procedure and the control underwent flap procedure only. Histologic analysis after 8 weeks of healing revealed the following results: 1. The height of gingival margin was 1.30{\pm}0.73mm$ above CEJ in the control and $1.40{\pm}0.78mm$ in the test group. There was no statistically significant difference between the two group. 2. The length of epithelial growth (the distance from CEJ to the apical end of JE) was $1.74{\pm}0.47mm$ in the control and $1.12{\pm}0.36mm$ in the test group. These was a statistically significant difference between the two groups (P<0.01). 3. The length of new cementum was $2.06{\pm}0.73mm$ in the control and $2.62{\pm}0.37mm$ in the test group. There was no statistically significant difference between the two groups. 4. The length of new bone was $1.83{\pm}0.74mm$ in the control and $2.39{\pm}0.59mm$ in the test group. There was no statistically significant difference between the two groups. These results suggest that the use of bioactive glass 1-wall intrabony defects has significant effect on the prevention of junctional epithelium migration, but doesn't have any significant effect on new bone and new cementum formation.

• Journal of Periodontal and Implant Science
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• v.27 no.1
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• pp.61-78
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• 1997

PDGF-BB has been recognized as a highly potential growth factor for guided tissue regeneration in periodontal defect. This study carried out histologic and histometric evaluation of $200ng/cm^2$ PDGF-BB loaded bioresorbable membrane made from polyglycolic and polylactic acid. It was tested for its biocompatibility, ability to prevent epithelial downgrowth and amount of periodontal regeneration. Without membrane and PDGF-BB unloaded bioresorbable membrane were used as control. Healthy six beagle dogs were used. Each dog was anesthetized and buccal flaps were reflected in the mandibular and maxillary premolar areas. Buccal alveolar bone between the mesiobuccal and distobuccal line angles was surgically removed on the lower 2nd and 4th premolar in mandible, 2nd premolar in maxilla, to a level 4mm apical to the cementoenamel junction with creating a Class II buccal furcation defect for available space. Care was taken not to remove the root cementum layer and rubber impression materials were placed over each surgically created defect. Flaps were repositioned and sutured. Reconstructive surgery was performed 1 month after defect preparation. PDGF-BB loaded membranes and controls were randomly placed on maxillary 2nd premolars and mandibular 2nd and 4th premolars. Plaque control regimen was instituted with daily brushing with a 0.1% chlorhexidine digluconate during experimental periods. The animals were sacrificed 2 and 5 weeks after surgery and undecalcified specimens were prepared for histologic evaluation. The degree of coronal regrowth of new bone, new cementum and the amonut of new bone areas formed on the defected area of the PDGF-BB loaded membrnae turned superior to without membrane and drug unloaded membrane. Experimental membrane could prevent the epithelial downgrowth irrespective of drug loaded or not and showed good biocompatiblity, These results implicated that PDGF-BB loaded bioresorbable membrane could be highly useful tool for guided tissue regeneration of periodontal defects.

• Journal of Periodontal and Implant Science
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• v.38 no.sup2
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• pp.317-324
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• 2008

Purpose: Aggregatibacter actinomycetemcomitans was associated with localized aggressive periodontitis, endocarditis, meningitis, and osteomyelitis. The cytolethal distending toxin (CDT) of A. actinomycetemcomitans was considered as a key factor of these diseases is composed of five open reading frames (ORFs). Among of them, An enzymatic subunit of the CDT, CdtB has been known to be internalized into the host cell in order to induce its genotoxic effect. However, CdtB can not be localized in host cytoplasm without the help of a heterodimeric complex consisting of CdtA and CdtC. So, some studies suggested that CdtC functions as a ligand to interact with GM3 ganglioside of host cell surface. The precise role of the CdtC protein in the mechanism of action of the holotoxin is unknown at the present time. The aim of this study was to generate recombinant CdtC proteins expression from A. actinomycetemcomitans, through gene cloning and protein used to investigate the function of Cdt C protein in the bacterial pathogenesis. Materials and Methods: The genomic DNA of A. actinomycetemcomitans Y4 (ATCC29522) was isolated using the genomic DNA extraction kit and used as template to yield cdtC genes by PCR. The amplifed cdtC genes were cloned into T-vector and cloned cdt C gene was then subcloned to pET28a expression vector. The pET28a-cdtC plasmid expressed in BL21 (DE3) Escherichia coli system. Diverse conditons were tested to opitimize the expression and purification of functional CdtC protein in E. coli. Results: In this study we reconstructed CdtC subunit of A. actinomycetemcomitans Y4 and comfirmed the recombinant CdtC expression by SDS-PAGE and Western Blotting. The expression level of the recombinant CdtC was about 2% of total bacterial proteins. Conclusion: The lab condition of procedure for the purification of functionally active recombinant CdtC protein is established. The active recombinant CdtC protein will serve to examine the role of CdtC proteins in the host recognition and enzyme activity of CDT and investigate the pathological process of A. actinomycetemcomitans in periodontal disease.

• Journal of Periodontal and Implant Science
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• v.38 no.sup2
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• pp.325-334
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• 2008

Purpose: The carrier used as delivery agent for bone morphogenetic proteins(BMPs) should also act as a scaffold for new bone formation. Moreover, bone formation should be predictable in terms of the volume and shape. This study examined the osteogenic effect of macroporous biphasic calcium phosphate (MBCP) block combined with ePTFE membrane as a carrier for recombinant human bone morphogenetic proteins (rhBMP-2). In addition, the additive effect of ePTFE membrane on bone formation was evaluated. Materials and Methods: Eight-millimeter critical sized calvarial defects were created surgically in 28 male Sprague-Dawley rats. The animals were divided into 2 groups containing 14 animals each. The defects were treated with either rhBMP-2/MBCP block (rhBMP-2/MBCP group) or rhBMP-2/MBCP block/ePTFE membrane (rhBMP-2/MBCP/ePTFE group). A disc-shaped MBCP block (3 mm height and 8 mm diameter) was used as the carrier for the rhBMP-2 and ePTFE membrane was used to cover the rhBMP-2/MBCP block. The histologic and histometric parameters were used to evaluate the defects after 2- or 8-week healing period (7 animals/group/healing interval). Results: The level of bone formation in the defects of both groups was significantly higher at 8 weeks than that at 2 weeks (P < 0.05). The ePTFE membrane has no additional effect compared with the rhBMP-2/MBCP block only. However, at 8 weeks, rhBMP-2/MBCP/ePTFE group showed more even bone formation on the top of the MBCP block than the rhBMP-2/MBCP group. Conclusion: These results suggest that the ePTFE membrane has no additive effect on bone formation when a MBCP block is used as a carrier for rhBMP-2.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.209-223
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• 2013

This study was to evaluate the stress distributions of prefabricated, customized abutments and fixtures according to their material and shape by three-dimensional finite element analysis. And to investigate the fatigue life and fracture characteristics. Mandibular models were fabricated by reconstruction of the CT scan of patients with normal occlusion. A total of six finite element models were designed, a load of 100 N was applied on the buccal cusps vertically, and 30 degree obliquely. 10 specimens each were fabricated for the more clinically widely used 4 type abutments and were loaded according to ISO 14801. Differences in stress distribution patterns were not found according to the materials of the abutments and fixtures. But a slight difference in the stress level was detected. Customized abutment groups showed lower crown stress levels. One-piece zirconia implant showed the lowest bone stress levels. In the fatigue test, highest values were measured in group 7. Prefabricated abutments showed less variation of fatigue life (P<0.05). Use of customized abutments can improve the fracture resistance of restorations. Especially, use of customized zirconia abutments reinforced by titanium screw connecting parts is recommended.