• Journal of Technologic Dentistry
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• v.42 no.4
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• pp.348-354
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• 2020

Purpose: Zirconia is differentiated from other ceramics because of its high resistance to corrosion and wear, excellent flexural strength (900~1400 MPa), and high hardness. Dental zirconia with proven mechanical/biological stability is suitable for the manufacture of implants. However, there are limited in vivo studies evaluating stress distribution in zirconia compared with that in titanium implants and studies analyzing finite elements. This study was conducted to evaluate the stress distribution of the supporting bone surrounding zirconia and titanium implants using the finite element analysis method. Methods: For finite element analysis, a single implant-supported restoration was designed. Using a universal analysis program, eight occlusal points were set in the direction of the occlusal long axis. The occlusal load was simulated at 700 N. Results: The zirconia implant (47.7 MPa) von Mises stress decreased by 5.3% in the upper cortical bone compared with the titanium implant (50.2 MPa) von Mises stress. Similarly, the zirconia implant (20.8 MPa) von Mises stress decreased by almost 4% in the cancellous bone compared with the titanium implant (21.7 MPa) von Mises stress. The principal stress in the cortical and cancellous bone exhibited a similar propensity to von Mises stress. Conclusion: In the supporting bone, the zirconia implant is able to reduce bone resorption caused by mechanically transferred stress. It is believed that the zirconia implant can be a potential substitute for the titanium implant by reinforcing aesthetic characteristics and improving stress distribution.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.3
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• pp.241-248
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• 2008

Tibial bone grafts provide an adequate volume of cancellous bone with cortical bone, high biologic value of bone, minimal gait disturbance and complications, and no special contraindications, and offer a superior clinical results than any other donor sites. Lateral appoach in tibial bone graft was used to gain large bone volume traditionally, but medial approach provides low morbidity associated with the tibial anatomic structure, simple and safety surgical procedure, and better comfortable to patients recently. We have undertaken clinical and retrospective studies on patients in Dept. of Oral and Maxillofacial Surgery, Inha University Hospital from April 2004 to January 2008. 50 patients have maxillofacial bony defect as resection of bening tumor, cyst enucleation, alveolar bone resorption, sinus pneumatization were received the tibial proximal autogenous particulated cancellous bone grafts. They were analyzed sex, age, diagnosis of recipient site, lesion size, dornor site, cortical bone repositioning, complications and we concluded favorable following results. 1. Medial approach for proximal tibia is safer and technically easier than lateral approach, associated with the proximal tibial anatomic structures, and short operative times. 2. Proximal tibia provides an adequate bone volume with predictability for oral and maxillofacial reconstruction. 3. Patients rarely complain of pain, swelling, discomfort and dysfunction such as gait disturbance. In conclusion, medial approach for proximal tibial graft seems to be a valuable tool for oral and maxillofacial reconstruction.

• Journal of Periodontal and Implant Science
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• v.37 no.4
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• pp.791-803
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• 2007

The purpose of this study was to evaluate exophytically vertical bone formation in residual ridge of the beagle dog by the concept of guided bone regeneration with a titanium reinforced e-PTFE membrane combined with irradiated cancellous human bone. Twelve male beagle dogs(mean age 1.5 years and mean weight 12kg) were used for this study. The alveolar ridges after extraction of all mandibular premolars were surgically and horizontally removed. At 8 weeks after extractions, full-thickness flap was reflected and cortical bone was removed with round bur and copious irrigation. Rectangular parallelepiped(10mm in length, 5mm in width, and 4mm in height) bended with titanium-reinforced e-PTFE(TR e-PTFE) membrane was placed on the decorticated alveolar ridge, fixed with metal pins and covered with full-thickness flap and assigned as a control group. Test groups ere treated with TR e-PTFE membrane filled with irradiated cancellous human bone. Of twelve beagle dogs, four control dogs and four test dogs without membrane exposure to oral cavity were sacrificed at 8 and 16 weeks respectively. The surgical sites were dissected out, fixed in 4% buffered formaldehyde, dyed using a Villanueva staining technique, and processed for embedding in plastic resin. The cutting and grinding methods were routinely processed for histologic and histomophometric analyis of exophytic bone formation as well as statistical analysis. The results of this study were as follows: 1. Exophytic bone formation in the both of experimental groups was increased respectively after surgery from 23.40% at 8 weeks to 46.26% at 16 weeks in the control groups, from 40.23% at 8 weeks to 47.11% at 16 weeks in the test groups(p<0.05). 2. At 8 weeks after surgery, exophytic bone formation was made 40.23% in the test groups and 33.40% in the control groups. Exophytic bone formation was significantly made in the test group more than in the control group. At 16 weeks after surgery, exophytic bone formation was made 44.11% in the test groups and 46.26% in the control groups. Exophytic bone formation was made in the test groups more than in the control groups, but there was no statistically significant differences. 3. The membrane was fixed with metal pins to closely contact it to the bone surface. So, collapse and deviation of the membrane could be prevented and in growth of connective tissue also could be blocked from the periphery of the membrane. On the basis of these findings, wee suggest that intraoral experimental model for exophytic bone formation may be effective to evaluate the effect of bone graft material. And it indicates that combined use of membrane and ICB graft material is more effective than use of membrane only for exophytic bone formation.

• Journal of Veterinary Clinics
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• v.17 no.1
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• pp.76-82
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• 2000

This study was undertaken to find out the effect of persimmon leaves on histopathological changes of cadmium toxicity in mice. Seventy two BALB/c mice of male were divided into a control group(A) and five experimental groups (B, C, D, E, F) : group A received tap water and basal diet, group B received tap water and diet supplemented with 3% persimmon leaves alone, group C received basal diet and 300 ppm cadmium, group D, E and F received basal diet supplemented with 1, 3% and 7% persimmon leaves and 300 ppm cadmium respectively. Cadmium dissolved in tap water was used, and the persimmon leaves were mixed with feed. All mice were dissected on the 84th day. Pathological changes in liver, kidney, cortical osseous tissue of femoral shaft, bone trabecular of femur, and epiphyseal cartilage plate of femur were observed. Group B showed no significant changes as the control group. But group C showed the unclearness of specific cells in liver, the loss of architecture and necrosis of hepatocyte, degeneration and necrosis of renal convoluted tubules, desquamation and vacuolization of the greater part of the renal tubular epithelium, marked thinning of the cortical osseous tissue in femoral shaft, reduction of cancellous bone volume and decreaswe of trabecular number, and marked thinning of epiphyseal cartilage plate in femur. On the other hand, persimmon leaves-treated group showed a little convalescent changes an maintained their normal architectures in liver, kidney, cortical osseous tissue of femoral shaft, bone trabecular of femur, and epiphyseal cartilage plate of femur.

• Journal of Periodontal and Implant Science
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• v.46 no.5
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• pp.291-302
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• 2016

Purpose: The aim of the present study was to evaluate the effectiveness of using a mineralized bone cortical allograft (MBCA), with or without a resorbable collagenous membrane derived from bovine pericardium, on alveolar bone remodeling after immediate implant placement in a dog model. Methods: Six mongrel dogs were included. The test and control sites were randomly selected. Four biradicular premolars were extracted from the mandible. In control sites, implants without an allograft or membrane were placed immediately in the fresh extraction sockets. In the test sites, an MBCA was placed to fill the gap between the bone socket wall and implant, with or without a resorbable collagenous membrane. Specimens were collected after 1 and 3 months. The amount of residual particles and new bone quality were evaluated by histomorphometry. Results: Few residual graft particles were observed to be closely embedded in the new bone without any contact with the implant surface. The allograft combined with a resorbable collagen membrane limited the resorption of the buccal wall in height and width. The histological quality of the new bone was equivalent to that of the original bone. The MBCA improved the quality of new bone formation, with few residual particles observed at 3 months. Conclusions: The preliminary results of this animal study indicate a real benefit in obtaining new bone as well as in enhancing osseointegration due to the high resorbability of cortical allograft particles, in comparison to the results of xenografts or other biomaterials (mineralized or demineralized cancellous allografts) that have been presented in the literature. Furthermore, the use of an MBCA combined with a collagen membrane in extraction and immediate implant placement limited the extent of post-extraction resorption.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.3
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• pp.233-238
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• 2014

Purpose: A method detecting change of jaw or alveolar bone density may be helpful in periodontal care, implant dentistry and evaluation of bone density of whole body. Materials and methods: In this study, bone density of intraoral periapical radiography using phantom-integrated XCP is compared with that of quantitative computed tomography (QCT). Results: Bone density of intraoral periapical radiography and the one measured by QCT showed high correlation (correlation coefficient = 0.92, P<.001) in alveolar bone, and relatively high correlation (0.73, P<.001) in cancellous bone. Conclusion: This study revealed possibility of scoring of bone density by intraoral periapical radiography.

• Archives of Plastic Surgery
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• v.38 no.3
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• pp.222-227
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• 2011

Purpose: Autogenous particulate bone grafting is a type of autogenous bone graft that consists of small particles of cortical and cancellous bone. Autogenous particulate bone grafting has been used for calvarial bone defect after calvarial defect of craniosynostosis and prevention of temporal depression after fronto-orbital advancement. The results were followed up and studied for effectiveness of autogenous calvarial particulate bone grafting. Methods: Cranial vault remodeling and fronto-orbital advancement was performed for six craniosynostosis patient from August 2005 to October 2007. Autogenous particulate bone grafting was harvested from endocortex of separated cranial vault and if insufficient, from extocortex of occipital region using Hudson brace & D'Errico craniotomy bit and was grafted on the calvarial bone defect of cranial vault and temporal hollow. Fibrin glues were added to the harvested particulated bone for adherence and shaping of paticles. Results: Autogenous particulate bone grafting was followed-up at least longer than I year. The calvarial bony defects following primary cranial remodeling were successfully covered and postoperative temporal depressions after fronto-orbital advancement were also well prevented by grafted particulated bone. Conclusion: Autogenous calvarial particulate bone graft can be harvested in infants and young children with minimal donor site morbidity. It effectively heals cranial defects in children and during fronto-orbital advancement reduces the prevalence of osseous defects independent of patient age. It's easy and effective method of reconstruction of calvarial defect.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.3
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• pp.276-279
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• 2001

Osteoma is defined as a benign neoplasm of bony tissue. Osteomas are divided into two groups: central and peripheral by origin, compact and cancellous by histopathologic findings. Solitary osteoma of jaw bone, not related with Gardner syndrom, is relatively uncommon. We present two cases of huge solitary peripheral osteomas: compact type exophyting osteoma on the inferolingual side of mandibular angle and cancellous type on the residual ridge of posterior maxilla, which is extremely rare.

• Journal of Veterinary Clinics
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• v.18 no.2
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• pp.116-123
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• 2001

This study was undertaken to find out the effect of Korean safflower seed powder on histopathological changes of cadmium toxicity in mice. Fifty BALB/c mice were divided into a control group(A) and four experimental groups(B, C, D, E) : group A received tap water and basal diet, group B received tap water and diet supplemented with 3% Korean safflower seed powder alone, group C received basal diet and 300 $\mu\textrm{g}$/g of cadmium, group D and E received basal diet supplemented with 3% and 10% Korean safflower seed powder and 300$\mu\textrm{g}$/g of cadmium respectively. Cadmium dissolved in tap water was used, and the Korean safflower seed powder were mixed with feed. All mice were dissected on the 56th day. Histopathological changes in liver, kidney, lung, cortical osseous tissue of femoral shaft, bone trabecular of femur, and epiphyseal cartilage plate of femur were observed. Group B showed no significant changes compared with the control group. But group C showed the unclearness of specific cells in liver, the loss of architecture and focal necrosis of hepatocyte, the glomerular swelling, degeneration and necrosis of convoluted tubules, desquamation and vacuolization of the greater part of the renal tubular epithelium, the marked congestion and thickness of the wall of alveolus in lung, slightly thinning of the cortical osseous tissue in femoral shaft, reduction of cancellous bone volume and marked narrowness of bone trabecular, marked thinning of epiphyseal cartilage plate and irregular arrangement of columnar structure of cartilage cells. On the other hand, Korean safflower seed powder-treated group showed a little convalescent changes and maintained their normal architectures in liner, kidney, lung, cortical osseous tissue of femoral shaft, bone trabecular of femur and epiphyseal cartilage plate of femur.

• Imaging Science in Dentistry
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• v.38 no.1
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• pp.49-56
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• 2008

Purpose: Diagnostic estimation of destruction and formation of bone has the typical limit according to capacity of x-ray generator and image detector. So the aim of this study was to find out how much it can reproduce the shape and the density of bone in the case of using recently developed dental type of cone beam computed tomography, and which image is applied by new detector and mathematic calculation. Materials and Methods: Cone beam computed tomography (PSR 9000N, Asahi Roentgen Ind. Co., Ltd., Japan) and soft x-ray radiography were executed on dry mandible that was already decalcified during 5 hours, 10 hours, 15 hours, 20 hours, and 25 hours. Estimating and comparing of those came to the following results. Results: The change of inferior border of mandible and anterior border of ramus in the region of cortical bone was observed between first 5 and 10 hours of decalcification. The reproduction of shape and density in the region of cortical bone and cancellous bone can be hardly observed at cone beam computed tomography compared with soft x-ray radiography. The difference of decrease of bone density according to hours of decalcification increase wasn't reproduced at cone beam computed tomography compared with soft x-ray radiography. Conclusion: CBCT images revealed higher spatial resolution. However, contrast resolution in region of low contrast sensitivity is the inferiority of images' property.