• Maxillofacial Plastic and Reconstructive Surgery
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• v.29 no.1
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• pp.1-9
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• 2007

Purpose: To evaluate the effect of compression on the distracted area in new bone formation during mandibular distraction osteogenesis in rabbits. Materials and method: Sixteen rabbits, weighing approximately 2 Kg, and the prefabricated distraction device were used. With the rabbits under general anesthesia, we performed vertical osteotomies between the anterior and posterior mandibular teeth and then placed the distraction device. After a 5 -day latency period, the mandible was distracted to a length of 10.0 mm at a rate of 1 mm/day and then immediately compressed 4 mm in the experimental group (n=8). In the control group (n=8), the mandible was distracted to a length of 6.0 mm at a rate of 1 mm/day. Rabbits in the control group were killed at 2 and 8 weeks during the consolidation period. The specimens were evaluated with light microscope after H & E stain. Histomorphometric analysis was done at 8 week specimens. Results: All experimental animals showed mandibular elongation on the macroscopical and radiographic evaluations. At 2 week, immature bone formation was observed from the surface of the host bone margins with collagen fibers arranged parallel to the direction of distraction in the control group; in the experimental group, immature bone formation was observed adjacent to the host bone, and the collagen fibers were not arranged uniformly. At 8 week, spindle-shaped new bone formation was seen in the direction of distraction in distracted area of the control group, while in the experimental group, the newly formed bone was arranged in a multidirectional manner, like the pattern of trabeculae. In the histomorphometric analysis of 8 weeks, the area of bone deposition was $2.12{\pm}\;0.75\;inch^2$ in the experimental group and $0.87{\pm}0.51\;inch^2$ in the control group (p<0.01). The bone deposition ratio was $29.60{\pm}10.50%$ in the experimental group and $12.10{\pm}7.17%$ in the control group (p<0.01). Conclusion: These results suggest that compression after over-distraction during the mandibular distraction osteogenesis is an effective method of increasing the amount of newly formed bone in distracted area.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.2
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• pp.131-138
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• 2007

The purpose of this study was to observe the effect of calcium and vitamin D to the titanium implant osseointegration in animal model. 32 rats, 10 weeks of age, were divided into two group: additional calcium and vitamin D supplementation group and a control group. Titanium screw implant(diameter, 2.0mm; length, 3.5mm; pitch-height 0.4mm) were placed into tibia of 32 rats, 16 in the control group and 16 in the experimental group. The rats were sacrificed at different time interval(1, 2, 4, and 8 weeks after implantation) for histopathologic observation, histomorphometric analysis and immunohistochemistry with osteocalcin and osteopontin antibody. Histopathologically findings, newly formed bone was seen at 1 weeks and became lamellar bone at 2 weeks, and mature trabecullar bone was seen at 4 weeks experimental group. In control group, thickness of regenerated bone increased till 4 weeks gradually and trabecullar bone was seen at 8 weeks. By histomorphometric analysis, bone marrow density was increased significantly at 1 and 2 weeks in experimental group compared to control group. Osteocalcin immunoreactivity was strong at 1 week experimental group and reduced after 4 weeks gradually. But it was continuously weakly from 1 to 4 weeks in control group. Osteopontin immunoreactivity was very strong in newly formed bone from 2 to 8 weeks experimental group. And the amount of osteopontin expression was more abundant in experimental group. The results of this study suggest that calcium and vitamin D supplementation promotes bone healing around dental implants

• Journal of Periodontal and Implant Science
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• v.38 no.1
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• pp.83-90
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• 2008

Purpose: This study investigated the osteoconductivity of natural calcium carbonate-derived bone substitutes, hen eggshell (ES), and compared with those of commercial bone substitutes. Materials and Methods: Osseous defects created in the rat calvaria were filled with particulated ES(ES-1), ES with calcium-deficient hydroxyapatite surface layer (ES-2), Biocoral(Inoteb, France), and Bio-Oss(Geistlich Pharma, Wolhusen, Switzerland). After 4 and 8 weeks of healing, histomorphometic analysis was performed to evaluate the amount of newly formed mineralized bone area (NB%). Results: Histologic and histomorphometric analysis showed new bone formation and direct bony contact with the grafted materials in all groups. At 4 weeks, Biocoral group showed greater NB% compared to Bio-Oss and ES-1 groups (P<0.05). At 8 weeks, Biocoral and ES-2 groups showed significantly greater NB% compared to Bio-Oss group (P<0.05). Conclusion: These results indicate that natural calcium carbonate-derived bone substitutes with microporous calcium-deficient hydroxyapatite surface layer may be an effective materials treating osseous defects.

• Journal of Periodontal and Implant Science
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• v.38 no.2
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• pp.163-170
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• 2008

Purpose: Biphasic calcium phosphates have been of great interest recently. Mixing adequate ratios of hydroxyapatite(HA) and beta-tricalcium phosphate($\beta$-TCP) allowed to control the resorption rate without distorting its osteoconductive property. This study evaluated the bone formation effect of newly developed biphasic calcium phosphate(BCP) in calvarial defect of rabbits. Materials and Methods: 6 male New Zealand rabbits were used. Four defects with 8mm in diameter were created on each animal. BCP with HA/$\beta$-TCP ratio of 7:3 and particle size of $0.5{\sim}1.0\;mm$ was used as the test group and bovine bone with $0.25{\sim}1.0\;mm$ particle size, as the control group. Both test and control group materials were randomly implanted in the calvarial defects and were covered witha polymer membrane. The animals were sacrificed after 12, 24, and 48 weeks of implantation under general euthanasia. Resin blocks were obtained and were stained by masson's trichrome for histological observation. Results: Overall results were uneventful without any defect exposure or inflammation. The amount of new bone formation and bone maturity increased with increase in healing period at both groups. New bone in test group was mostly formed along the material particle surrounded by osteoblasts, and observation of osteoblastic stream was also present. Bone maturity increased as it was closer to thedefect margins. Under the same healing period, the test group showed more bone formation than the control group with more stable bovine bone particles remaining even after 48 weeks, whereas considerable resorption took place in BCP. Almost total defect closure was observed in test group with new bone formation in the central part of the defect. However, limited new bone formation was observed in the control group. Conclusion: Within the limits of the study, the present study reveals the newly developed BCP to be a good osteoconductive material. However, further studies are needed to be conducted in a different study model with a larger sample size.

• Journal of Periodontal and Implant Science
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• v.29 no.3
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• pp.447-472
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• 1999

The preclinical and clinical studies reviewed herein show that rhBMP-2 induces normal physiologic bone in relevant defects in the craniofacial skeleton. The newly formed bone assumes characteristics of the adjacent resident bone, and allows placement and osseointegration of dental implants. Clearly, the bone inducing capacity of rhBMP-2 is carrier and site dependent. rhBMP-2 in an absorbable collagen sponge carrier induces relevant bone formation in space providing defects. Space providing carries extends this possibility to non-space providing sites. Notably, some ceramic and polymeric biomaterials may substantially interfere with rhBMP-2 induced osteogenesis.

• The Journal of Advanced Prosthodontics
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• v.6 no.6
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• pp.521-527
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• 2014

This case series evaluated the clinical efficacy of autogenous tooth bone graft material (AutoBT) in alveolar ridge preservation of an extraction socket. Thirteen patients who received extraction socket graft using AutoBT followed by delayed implant placements from Nov. 2008 to Aug. 2010 were evaluated. A total of fifteen implants were placed. The primary and secondary stability of the placed implants were an average of 58 ISQ and 77.9 ISQ, respectively. The average amount of crestal bone loss around the implant was 0.05 mm during an average of 22.5 months (from 12 to 34 months) of functional loading. Newly formed tissues were evident from the 3-month specimen. Within the limitations of this case, autogenous tooth bone graft material can be a favorable bone substitute for extraction socket graft due to its good bone remodeling and osteoconductivity.

• Journal of Periodontal and Implant Science
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• v.23 no.2
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• pp.261-281
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• 1993

The author transplanted periodontally-diseased teeth which had been treated with citric acid into a clinically healthy extraction sockets and periodontally-affected extraction sockets, and compared with the healing processes within these tissues. Recipient sites were prepared by surgically removing a part of alveolar bone of premolars of adults dogs, placing elastic orthodontic ligatures for 8weeks, thereby inducing periodontal disease. The diseased roots were extracted and transplanted into healthy extraction sockets, and these were designated as control group 1. Diseased roots transplanted into diseased sockets were designated as control group 2. Diseased roots which had been root planed, treated with citric acid and transplanted into healthy sockets were designated as experimental group 1, while identically treated roots which had been transplanted into diseased sockets were designated as experimental group 2. Observations were made at weeks 2, 8 and 12, with following results. 1. At week 2, experimental group 2 showed some inflammatory cell infiltration in the connective tissue above the extraction sockets, while control groups showed less inflammatory or foreign body reactions throughout the experiment. 2. In both control groups, root surface resorption was observed throughout the experiment, while experimental groups showed a little resorption. 3. Control group 1 & 2 showed ankylosis by newly-formed bone ground the resorbed root surfaces, while experimental group 1 & 2 displayed collagen fibers which are not functionally-arranged, with random, loose arrangement or parallel orientation to root surfaces, and newly-formed bone outside of them. 4. In both control groups & experimental groups which had been transplanted into a clinically healthy extraction sockets & periodontally affected extraction sockets groups, histological differences were not significant. 5. Root resorption or ankylosis in control group 1 & 2 had increased quantitatively as experiment progressed. 6. New bone formation developed from the base and lateral wall of extraction sockets. In both control groups & experimental groups, root surfaces lying next to the upper portion of extraction sockets showed little alveolar bone formation and surrounded by connective tissue fiber at weeks 2 & 8, while at weeks 12, they did show alveolar bone formation. 7. At week 12, experimental group 2 showed numerous cells which appeared to be periodontal ligament cells, with functionally arranged connective tissue fibers between the roots and alveolar bone.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.6
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• pp.397-406
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• 2003

The purpose of this study was to observe the titanium implant osseointegration in the osteoporosis-induced animal model. Seventy rats, 11 weeks of age, were divided into two groups : an ovariectomized group and a control group. Titanium screw implants(diameter, 2.0mm; length, 3.5mm) were placed into left tibias of 70 rats, 35 in the control group and 35 in the experimental group. The rats were sacrificed at different time interval (1, 2, 3, 4, 6, 8, and 12 weeks after implantation) for histopathologic observation, histomorphometric analysis and immunohistochemistry with fibronectin and CD34 antibody. The results obtained from this study were as follows: 1. Histopathologically findings, newly formed bone was seen at 3 weeks and became lamellar bone at 8 weeks, and mature trabecullar bone was seen at 12 weeks control group. In experimental group, thickness of regenerated bone increased till 8 weeks gradually and mature trabecullar bone was seen at 12 weeks. 2. By histomorphometric analysis, marrow bone density and contact ratio of marrow bone to implant decreased significantly from 8 to 12 weeks in experimental group compared to control group and also total bone to implant contact ratio decreased significantly from 8 to 12 weeks in experimental group. 3. Fibronectin immunoreactivity was strong at 3 weeks control group and reduced after 8weeks gradually. But it was continuously strong from 3 to 8 weeks in experimental group. 4. CD34 immunoreactivity was very strong in the newly formed osteoblasts from 3 to 8 weeks control group. But it reacted minimally later. While in experimental group, it reacted continuously strong from 3 to 12 weeks. The results of this study suggest that osteoporosis is not an absolute contraindication to dental implantation if sufficient period suggested after fixture installation till second stage surgery.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.20-42
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• 1998

The present study was designed to understand the basic principles of the laser system and to assess the optimal coditions of the Nd:YAG laser irradiation system in order to expand the use of the laser system in the dental field. The laser system used in this study was a pulsed-wave output type and the power level is 9 watts. The incisors of developing rats were irradiated with the laser system explained above for 0.5, 1, and 2 seconds giving energy density 71, 167, and 215 J/$cm^2$ respectively. The rats were sacrificed just after irradiation or 10 minutes and 10 days after irradiation. The specimens were examined with the stereoscope, light microscope and transmission electron microscope. The results are as follows: 1. The tissue removal efficiency (depth of the cavity formed) is increased with the energy density after Nd:YAG laser irradiation. 2. The carbonized area is increased with the energy density. Cracks and melted appearance are seen in all kinds of the energy densities. 3. The lacunae in the damaged alveolar bone by the laser irradiation were empty, while those in the newly formed bone were occupied with the osteocytes. The damaged alveolar bone was repaired by the osteoblasts and macrophages on the periphery of the bone matrix. 4. The damaged enamel was replaced by the loose connective tissues showing many kinds of cells. The ameloblasts were differntiated on the replaced loose connective tissue. 5. The damaged dentin was repaired by the irregular dentin formed by the odontoblasts differentiated from the mesenchymal cells migrated from the pulp core.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.9.1-9.9
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• 2016

Background: As dental implants receive masticatory stress, the distribution of stress is very important to peri-implant bone homeostasis and implant survival. In this report, we created a saddle-type implant and analyzed its stability and ability to distribute stress to the surrounding bone. Methods: The implants were designed as a saddle-type implant (SI) that wrapped around the alveolar bone, and the sizes of the saddles were 2.5, 3.5, 4.5, and 5.5 mm. The X and Y displacement were compared to clarify the effects of the saddle structures. The control group consisted of dental implants without the saddle design (CI). Using finite element modeling (FEM), the stress distribution around the dental implants was analyzed. Results: With saddle-type implants, saddles longer than 4.5 mm were more effective for stress distribution than CI. Regarding lateral displacement, a SI of 2.5 mm was effective for stress distribution compared to lateral displacement. ASI that was 5.6 mm in length was more effective for stress distribution than a CI that was 10 mm in length. Conclusions: The saddle-type implant could have a bone-gaining effect. Because it has stress-distributing effects, it might protect the newly formed bone under the implant.