• Journal of Periodontal and Implant Science
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• 제35권3호
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• pp.635-648
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• 2005

The procedure that enhances osteogenesis and shortens the healing period is required for successful implant therapy. It has been introduced that osteogenesis is enhanced by the generation of electric field. Many researchers have demonstrated that application of electric and electromagnetic field promote bone formation. It also has been shown that electrical stimulation enhances peri-implant bone formation. Recently, several investigators have reported that noninvasive electrical stimulation using negatively charged electret such as polytetrafluoroethylene(PTFE) promotes osteogenesis. Therefore, we were interested in the effect of noninvasive electrical stimulation using negatively charged electret on the periimplant bone healing. After titanium implant were installed in the proximal tibial metaphysis of New Zealand white rabbit, negatively charged PTFE membrane fabricated by corana dischage was inserted into the inner hole of the experimental implant and noncharged membrane was applied into control implant. After 4 weeks of healing, histomorphometric analysis was performed to evaluate peri-implant bone response. The histomorphometric evaluations demonstrated experimental implant tended to have higher values in the total bone-to-implant contact ratio(experimental ; $49.9{\pm}13.52%$ vs control ; $37.5{\pm}19.44%$) , the marrow bone contact ratio(experimental ; $34.94{\pm}13.32%$ vs control ; $24.15{\pm}13.69%$), amount of newly formed bone in the endosteal region(experimental ; $1.00{\pm}0.30mm$ vs control ; $0.61{\pm}0.24mm$) and bone area in the medullary canal(experimental ; $13.55{\pm}4.98%$ vs control ; $9.03{\pm}3.05%$). The mean values of the amount of newly formed bone(endosteal region) and bone area(medullary canal) of the experimental implant demonstrated a statistically significant difference as compared to the control implant(p<0.05). In conclusion, noninvasive electrical stimulation using negatively charged electret effectively promoted peri-implant new bone formation in this study. This method is expected to be used as one of the useful electrical stimulation for enhancing bone healing response in the implant therapy

• Journal of Periodontal and Implant Science
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• 제39권3호
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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.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제35권5호
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• pp.294-301
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• 2013

Purpose: The purpose of this study is to assess the effectiveness of beta-tricalciumphosphate (${\beta}$-TCP) as a bone graft material on new bone formation and regeneration of mandible bone defect around dental implants. Methods: Both mandibular sites of ten rabbits were exposed. The experimental subjects were divided into two groups. Rabbits in the control group (right site of the mandible) had dental implants around cortical bone defects, without treatment, while, in the experimental group (left site of the mandible), ${\beta}$-TCP was grafted into the bone defect around the implant. Rabbits were sacrificed after one, two, three, four, and eight weeks, and histomorphometric evaluation and analysis of the bone implant contact rate were performed using an optical microscope. Results: Bone formation rates in the experimental group were greater than those in the control group from one to eight weeks, and percentages of implant surface contacted to bone were greater in the experimental group than in the control group from three weeks after implantation. Conclusion: These results suggest that the bone formation activity around dental implants was increased by osteoconduction activity of ${\beta}$-TCP.

• 대한치과교정학회지
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• 제48권5호
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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 Periodontal and Implant Science
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• 제34권1호
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• pp.35-48
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• 2004

Since the occlusal loading is transmitted to the surrounding bone, the success of an implant treatment is closely related to the distribution of the stress on the implant. The finite element analysis method is often used in order to produce a model for dispersion of stress. Assessment of the success of the implant is usually based on the degree of osseointegration which is a bone and implant surface interface. Implant used in this research was designed through the method of shape optimization after the stress on implant was anaylzed by the finite element analysis method. This study was pertinently assessed by a clinical, histologic, histomorphometric analysis after the shape optimized implant was installed on beagle dog tibia. The results are as follows 1. It clinically showed a good result without mobility and imflammatory reaction. 2. Implant was supported by dense bone and bone remodeling showed on the surrounding area of the implant 3. The average percentage of bone-implant contact was 58.1%.The percentage of bone density was 57.6%. Having above results, shape optimized implant showed the pertinence through clinical and histologic aspects. However, to use the shape optimized implant, the further experiment is required for finding problems, improvement.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제34권1호
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• pp.90-94
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• 2008

The purpose of this study was to investigate the effects of immediate non-functional loading by analyzing histomorphology around the implant tissues in dogs. Five eight- to nine-month-old full-grown dogs weighing around 12 kg were used in the study. Group I (control group) comprised those in which delayed loading was applied to the right side of the mandible, and Group II (experimental group) consisted of dogs in which immediate loading was performed on the left side of the mandible. Resorbable blast media (RBM)-treated double-threaded US III implants measuring 3.5 mm in diameter and 11 mm long were used in the study. Each animal received four implants in each group, for a total of 40 implants. Cemented type abutments were used after implantation. An 8-week period was allowed for bone healing and an abutment was placed after exposing the periosteum for loading. An implant sample was obtained from bone blocks taken when the dogs were killed at 16 weeks after loading. A Mann-Whitney U-test was performed to evaluate statistical significance. Student's t-test was used for the histological evaluation. The bone formation ratio in Groups 1 and 2 was 88.23 and 86.41%, respectively. No significant difference in new bone formation was observed in the two groups. As no significant difference was seen in new bone formation between the delayed and immediate loading groups, early loading might be possible after implant placement.

• Imaging Science in Dentistry
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• 제40권3호
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• pp.123-129
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• 2010

Purpose : To evaluate the effect of surgical treatment of ligature-induced peri-implantitis in dogs using fractal analysis. Also, the capabilities of fractal analysis as bone analysis techniques were compared with those of histomorphometric analysis. Materials and Methods : A total of 24 implants were inserted in 6 dogs. After a 3-months, experimental periimplantitis characterized by a bone loss of about 3 mm was established by inducing with wires. Surgical treatment involving flap procedure, debridement of implants surface with chlorhexidine and saline (group 1), guided bone regeneration (GBR) with absorbable collagen membrane and mineralized bone graft (group 2), and $CO_2$ laser application with GBR (group 3) were performed. After animals were sacrificed in 8 and 16 weeks respectively, bone sections including implants were made. Fractal dimensions were calculated by box-counting method on the skeletonized images, made from each region of interest, including five screws at medial and distal aspects of implant, were selected. Results : Statistically significant differences in the fractal dimensions between the group 1($0.9340{\pm}0.0126$) and group 3($0.9783{\pm}0.0118$) at 16 weeks were found (P<0.05). The fractal dimension was statistically significant different between 8($0.9395{\pm}0.0283$) and 16 weeks in group 3 (P<0.05). These results were similar with the result of the evaluation of new bone formation in histomorphometric analysis. Conclusions : Treatment of experimental peri-implantitis by using $CO_2$ laser with GBR is more useful than other treatments in the formation of new bone and also the tendency of fractal dimension to increase relative to healing time may be a useful means of evaluating.

• Journal of Periodontal and Implant Science
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• 제49권3호
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• pp.148-157
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• 2019

Purpose: This study aimed to evaluate periodontal and pulpal healing in replanted rat teeth, preserved under different storage conditions, with or without root conditioning using doxycycline. Methods: A total of 40 maxillary first molars extracted from 20 Sprague-Dawley rats were stored for different durations under different conditions (5 minutes in dry storage and 60 minutes in Hank's balanced salt solution [HBSS]) and subsequently replanted. The rats were divided into 2 groups based on the use of root surface treatment: the doxycycline group (root surface treated with doxycycline) and the control group (no doxycycline treatment). Eight weeks after replantation, the animals were sacrificed, and the teeth were evaluated using micro-computed tomography (micro-CT) and histomorphometric analysis. Results: In the micro-CT analysis, the doxycycline group showed the same rate of occurrence of periapical radiolucency as was observed in the control group, but a lower degree of root resorption in teeth replanted after 60 minutes of storage in HBSS (P<0.05). In the histomorphometric analysis, the doxycycline group exhibited no improvement in either pulpal or periodontal healing of the replanted tooth after 5 minutes of dry storage, but showed a lower grade of surface root resorption ($1.37{\pm}0.77$) and inflammatory resorption in the teeth stored for 60 minutes in HBSS ($1.33{\pm}0.71$). Conclusions: In conclusion, doxycycline improved the periodontal healing of replanted teeth stored for 60 minutes in HBSS, whereas doxycycline did not improve periodontal healing of replanted tooth after 5 minutes of dry storage. Within the limits of this study, doxycycline showed more favorable periodontal healing despite delayed replantation.

• Journal of Periodontal and Implant Science
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• 제40권3호
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• pp.132-138
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• 2010

Purpose: The purpose of this study was to compare the bone regeneration effects of cortical, cancellous, and cortico-cancellous human bone substitutes on calvarial defects of rabbits. Methods: Four 8-mm diameter calvarial defects were created in each of nine New Zealand white rabbits. Freeze-dried cortical bone, freeze-dried cortico-cancellous bone, and demineralized bone matrix with freeze-dried cancellous bone were inserted into the defects, while the non-grafted defect was regarded as the control. After 4, 8, and 12 weeks of healing, the experimental animals were euthanized for specimen preparation. Micro-computed tomography (micro-CT) was performed to calculate the percent bone volume. After histological evaluation, histomorphometric analysis was performed to quantify new bone formation. Results: In micro-CT evaluation, freeze-dried cortico-cancellous human bone showed the highest percent bone volume value among the experimental groups at week 4. At week 8 and week 12, freeze-dried cortical human bone showed the highest percent bone volume value among the experimental groups. In histologic evaluation, at week 4, freeze-dried cortico-cancellous human bone showed more prominent osteoid tissue than any other group. New bone formation was increased in all of the experimental groups at week 8 and 12. Histomorphometric data showed that freeze-dried cortico-cancellous human bone showed a significantly higher new bone formation percentile value than any other experimental group at week 4. At week 8, freeze-dried cortical human bone showed the highest value, of which a significant difference existed between freeze-dried cortical human bone and demineralized bone matrix with freeze-dried cancellous human bone. At week 12, there were no significant differences among the experimental groups. Conclusions: Freeze-dried cortico-cancellous human bone showed swift new bone formation at the 4-week healing phase, whereas there was less difference in new bone formation among the experimental groups in the following healing phases.

• 대한치과보철학회지
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• 제33권3호
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• pp.550-568
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• 1995

The purpose of this study was to observe the effects of early functional on bone formation around titanium plsama sprayed IMZ implants. 15 IMZ implants were inserted on the mandibular premolar areaa in 5 mondgrel dogs. The inplants were divided into 4 groups according to it’s loading schedule : Temporary abutments were connected for functional loading 6weeks, 9weeks, and 12weeks after implants installation in group I, II, and III, respectively. Abutments were not connected in the control group. After polyfluorochrome sequential labeling, all animals were sacrificed and bone sections includig implants and the 1st. molar were removed and processed for histologic evaluation. From light and fluorescence microscopic evaluation as well as histomorphometric and EPMA analysis, following results were obtained : 1. Light microscopically, the osteoid tissues were observed much in the compact bone of unloaded group, and cancellous bone formation observed more in early loaded group. 2. Calcification and remodeling of bone took place faster in loaded group, especially in 6 weeks group. 3. Moderate to severe marginal bone resorption was observed in 6 weeks group, mainly on buccal crest. 4. There was no difference in the percentages of bone-to-metal contact among the experimental groups. 5. In quantitative analysis using EPMA, there was no difference in the content of calcium and phosphorus among the experimental groups, regardless of distance.