• Journal of Periodontal and Implant Science
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• v.39 no.3
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• pp.321-329
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• 2009

Purpose: The purpose of this study was to evaluate the bone regeneration of particulated hydroxyapatite(HA) and block type of hydroxyapatite graft in rabbit calvarial defects. Methods: An 8 mm calvarial circular defects were created in sixteen young adult New Zealand white male rabbits (weight $3.0{\sim}3.5kg$). Each defects were filled with Bio-Oss, particulated HA and block type HA. Sham surgery control defects were filled with blood clots. The specimens were harvested at 4 weeks and 8 weeks for histologic and histomorphometric evaluation. Results: Histomorphometric analysis demonstrated statistical differences in defect closure, new bone formation, and bone density of the four groups. Block type of HA group showed increased bone formation and bone density at 4 weeks and 8 weeks compared with Bio-Oss group or sham surgery control group(p<0.05). Conclusions: Block type of HA is an effective material for osteoconduction in rabbit calvarial defects, which may acts as a guide in use of these products in human application.

• Journal of Korean Neurosurgical Society
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• v.52 no.1
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• pp.1-6
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• 2012

Objective : The purpose of this study was to evaluate the different patterns of bone loss between the lumbar spine and the femur after ovariectomy in rats. Methods : Twenty-four female Sprague-Dawley rats underwent a sham operation (the sham group) or bilateral ovariectomy (the ovariectomized group). Four and eight weeks after operation, six rats from each of the two groups were euthanized. Serum biochemical markers of bone turnover including osteocalcin and alkaline phosphatase (ALP), which are sensitive biochemical markers of bone formation, and the telopeptide fragment of type I collagen C-terminus (CTX), which is a sensitive biochemical marker of bone resorption, were analyzed. Bone histomorphometric parameters of the 4th lumbar vertebrae and femur were determined by micro-computed tomography. Results : Ovariectomized rats were found to have higher osteocalcin, ALP and CTX levels than sham controls. Additionally, 8 weeks after ovariectomy in the OVX group, serum levels of osteocalcin, ALP and CTX were significantly higher than those of 4 weeks after ovariectomy. Bone loss after ovariectomy was more extensive in the 4th lumbar spine compared to the femur. Bone loss in the 4th lumbar spine was mainly caused by trabecular thinning, but in the femur, it was mainly caused by trabecular elimination. Conclusion : The present study demonstrates different patterns of bone loss between the 4th lumbar spine and the femur in ovariectomized rats. Therefore, when considering animal models of osteoporosis, it is important that bone sites should be taken into account.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.5
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• pp.282-292
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• 2003

Several agents are in use to promote new bone formation during bone graft procedures in maxillofacial region. Among them, we have used crude BMP, PRP, and P-15 for experimentally created defects with accompanying graft materials in the rabbit model. The aim of this study is to analyze the effect of above mentioned agents on bone formation using histologic and histomorphometrical methods, thus to provide experimental support for clinical application of these agents. Six rabbits were used as experimental animals. Four surgical defects were created on the distal femoral heads of each animal using trephine drill. The defects were filled with each agents with accompaning graft materials as experimental groups and particulate corti-co-cancellous autogenous graft as control. For histomorphometric analysis, fluorescent dye was injected at 2week and 1week before sacrifice. Then, the animals were sacrificed at 2, 4 and 8weeks after surgery and histologic and histomorphometric examinations were achieved. At two weeks after bone graft, bone formation and active remodeling process were examined in all experimental groups and the control. But the intensity of such activities of the experiments were somewhat weaker than that of the control. In BMP group, the amount of newly formed osteoid was increased constantly and the amount was preserved constantly in PRP group. But in P-15 group, the amount of newly formed osteoid was decreased with time to 8week after surgery. Histologic findings showed superior bony quantity and quality in PRP group than that of P-15 group. MAR(Mineralization Apposition Rate) of all experimental groups were slower than that of control group. In P-15 group, constant foreign body reaction was observed at all periods and the graft material showed inwardly destroyed characteristics rather to mature. The data from this study provide the basis for future studies for evaluating the long-term remodeling process and foreign body reactions observed in P-15 group and clinical study for predictable use of these agents.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.42 no.6
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• pp.345-351
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• 2016

Objectives: This study compared the impact of implant surface treatment on the stability and osseointegration of implants in dog mandibles. Materials and Methods: Six adult dogs received a total of 48 implants that were prepared using four different surface treatments; resorbable blast media (RBM), hydroxyapatite (HA), hydrothermal-treated HA, and sand blasting and acid etching (SLA). Implants were installed, and dogs were separated into 2- and 4-week groups. Implant stability was evaluated via Periotest M, Osstell Mentor, and removal torque analyzers. A histomorphometric analysis was also performed. Results: The stability evaluation showed that all groups generally had satisfactory values. The histomorphometric evaluation via a light microscope revealed that the HA surface implant group had the highest ratio of new bone formation on the entire fixture. The hydrothermal-treated HA surface implant group showed a high ratio of bone-to-implant contact in the upper half of the implant area. Conclusion: The hydrothermal-treated HA implant improved the bone-to-implant contact ratio on the upper fixture, which increased the implant stability.

• The korean journal of orthodontics
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• v.48 no.5
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• pp.283-291
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• 2018

Objective: This study was conducted to perform histomorphometric evaluations of the bone surrounding orthodontic miniscrews according to their proximity to the adjacent tooth roots in the posterior mandible of beagle dogs. Methods: Four male beagle dogs were used for this study. Six orthodontic miniscrews were placed in the interradicular spaces in the posterior mandible of each dog (n = 24). The implanted miniscrews were classified into no loading, immediate loading, and delayed loading groups according to the loading time. At 6 weeks after screw placement, the animals were sacrificed, and tissue blocks including the miniscrews were harvested for histological examinations. After analysis of the histological sections, the miniscrews were categorized into three additional groups according to the root proximity: high root proximity, low root proximity, and safe distance groups. Differences in the bone-implant contact (BIC, %) among the root proximity groups and loading time groups were determined using statistical analyses. Results: No BIC was observed within the bundle bone invaded by the miniscrew threads. Narrowing of the periodontal ligament space was observed in cases where the miniscrew threads touched the bundle bone. BIC (%) was significantly lower in the high root proximity group than in the low root proximity and safe distance groups. However, BIC (%) showed no significant differences among the loading time groups. Conclusions: Regardless of the loading time, the stability of an orthodontic miniscrew is decreased if it is in contact with the bundle bone as well as the adjacent tooth root.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.4
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• pp.291-296
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• 2003

The use of resonance frequency analysis (RFA) provides a possibility to clinically measure implant stability and osseointegration. The implant stability quotient (ISQ) value of RFA is well known that influenced by effective abutment length and stiffness of the implant in the surrounding tissues. Among these factors stiffness is not accurately defined histologically yet. And the purpose of this study was to find the histolgical relationship of RFA. 17 implants in 3 beagle dogs were used for this study. Among these implants 10 were survived for 7 months, 4 were survived for 3 months and 3 were immediate status after placement. Resonance frequency analyses were conducted and the dogs were sacrificed. Percentage of the bone to implant contact (BIC) in the interface, percentage of the mineralized bone (bone area) within the threads of the implant, and marginal bone level were measured under light microscopy. The correlation between resonance frequency and histomorphometric measurements were analysed and following results were obtained. 1. There was statistically significant correlation between ISQ value and BIC on healed implants. But ISQ value and BIC of all implants were not significantly correlated. (P<0.01) 2. Significant correlation between ISQ value and bone area was not found in this study. 3. There was statistically significant correlation between ISQ value and marginal bone level on all implants as well as on healed implants. (P<0.01).

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.4
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• pp.312-321
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• 2007

Purpose: Distraction osteogenesis has been applied to the maxillofacial implantology and good experimental and clinical results have been reported. However, histologic studies of implants placement on distraction osteogenesis of atrophic alveolar ridges are scarce. In this study, we compare the bone formation between in the transport part and in the distraction part by histomorphometric analysis. Materials & methods: Three adult beagle dogs were served as experimental subjects. The 2 premolars and 1st molar were extracted on the Lt. side of mandible in each beagle dog. After one month later, osteotomy was performed and distraction device was adapted. Distraction was performed with gradual incremental separation of two bone pieces at a rate of 1.0mm per day for 5 days. During consolidation phase, new bone was formed in the distraction zone between the separated bone pieces. 5 weeks after distraction phase, 3 implants were placed in each beagle dog. The implants were inserted through transport part and distraction part and inferior basal bone. The animals were sacrificed at 2 weeks, 4 weeks, and 12 weeks after implant placement. BIC and BA of implants on distraction part and transport part were measured histomorphometrically. Results: BIC, BA increased after implant placement as time goes by passes and new bone formation was slightly higher in transport part than in distraction part at 2 weeks, 4 weeks after implant placement. At 12 weeks after implant placement, BIC, BA of were 74%, 61% in transport part and 77%, 59% in distraction part, therefore there were no difference in BIC and BA between transport part and distraction part at 12 weeks after implant placement.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.5
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• pp.365-374
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• 2011

Introduction: Research on dental bone graft material has been actively conducted. Recently, demineralized dentin matrix material has been developed and introduced. This study examined the effect of demineralized dentin matrix material on bone healing. Subjects and Methods: The patients who received no treatment after extraction were used as the control group and patients who underwent demineralized dentin matrix material application in the extraction socket after extraction were used as the experimental group. Panorama radiography was performed at the baseline and at 3.5 months after graft material placement and CT was taken at 3.5 months after graft material placement for a radiologic evaluation. Bony tissue specimens were collected from the alveolar crest in the middle of the extraction socket using a 2 mm trephine bur after 3.5 months for the histology and hostomorphometric study. Results: 1. On the panoramic view, a higher bone density was observed in the subject group. 2. On the panoramic view, the bone density increased significantly in the extraction socket, from the baseline to 3.5 months: a 7 and 10 gray-level scale was observed in the control and experimental group, respectively (P<0.05). 3. The CT view evaluation at 3.5 months revealed significantly higher bone density in the subject group than the control group (P<0.05). 4. The histological findings showed more active new bone and lamellar bone formation in the subject group. Dentin with osteoinduction ability and enamel with osteoconduction ability appeared. 5. On histomorphometric analysis, the subject group showed significantly more new bone, lamellar bone area and lower soft tissue area (P<0.05). The difference between the groups was significant (P<0.05). Conclusion: Bone healing was improved after the application of demineralized dentin matrix material and there was active new bone and lamellar bone formation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.1
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• pp.49-58
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• 2008

Objective: The Purpose of the study was to investigate the bone morphogenic protein expression of rhBMP-2(recombinant human bone morphogenic protein-2) as singnaling molecule and ${\beta}-TCP$(Tricalcium phosphate) as a bone substitute and carrier medium of rhBMP-2. Materials and Methods: 16 rabbits divided into 2 group of each 8 rabbit. Two standardized bone defect, round bilateral defect was made in the cranium of the 8 rabbit of first group, and was grafted with $150{\sim}500{\mu}m$ diameter ${\beta}-TCP$ 0.25g in one side, which was soaked with rhBMP-2, and autogenous bone was grafted on another side as a positive control. Second group of 8 rabbit, only ${\beta}-TCP$ was grafted with same size and same manner. After 2, 4, 8, and 12 weeks, specimen was taken for microscopic immunohiostochemical and histomorphometric analysis. Result: Grafting ${\beta}-TCP$ with rhBMP show the early formation of the bone regenerative factor (BMP-4) and more quantity of new bone formation than only use of ${\beta}-TCP$ (8,12 week), even show less new bone formation than autogenous bone. Conclusion : The experimental study result that ${\beta}-TCP$ graft combination with rhBMP-2 as a delivery system is an effective with osteoinductive capacity and biodegradable properties, so that provide clinical availibility of composite use in reconstruction of bony defect.

• Journal of Periodontal and Implant Science
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• v.47 no.1
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• pp.51-63
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• 2017

Purpose: Following tooth extraction, alveolar ridge preservation (ARP) can maintain the dimensions of ridge height and width. Although previous studies have demonstrated the effects of ARP, few if any studies have investigated the compressive force applied during grafting. The aim of this study was to determine the effects of different compressive forces on the graft materials during ARP. Methods: After tooth extraction, sockets were filled with deproteinized bovine bone mineral with 10% porcine collagen and covered by a resorbable collagen membrane in a double-layered fashion. The graft materials were compressed using a force of 5 N in the test group (n=12) and a force of 30 N in the control group (n=12). A hidden X suture was performed to secure the graft without primary closure. Cone-beam computed tomography (CBCT) was performed immediately after grafting and 4 months later, just before implant surgery. Tissue samples were retrieved using a trephine bur from the grafted sites during implant surgery for histologic and histomorphometric evaluations. Periotest values (PTVs) were measured to assess the initial stability of the dental implants. Results: Four patients dropped out from the control group and 20 patients finished the study. Both groups healed without any complications. The CBCT measurements showed that the ridge volume was comparably preserved vertically and horizontally in both groups (P>0.05). Histomorphometric analysis demonstrated that the ratio of new bone formation was significantly greater in the test group (P<0.05). The PTVs showed no significant differences between the 2 groups (P>0.05). Conclusions: The application of a greater compressive force on biomaterials during ARP significantly enhanced new bone formation while preserving the horizontal and vertical dimensions of the alveolar ridge. Further studies are required to identity the optimal compressive force for ARP.