• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.5
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• pp.265-269
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• 2015

The purpose of this study was to investigate implant-supported restoration as a technique for restoring missing teeth in patients with aplastic anemia. Recurrent bleeding from wound sites leads to persistent release of iron in the tissue. Excessive iron in tissue is related to clinical findings, including fibrosis, poor wound healing, and high level of angiogenesis, which are possible etiological factors of reduced osseointegration. A 44-year-old female patient with aplastic anemia was treated with multiple endosseous implants throughout the mandible and in the posterior region of the maxilla. After 14 implants were placed, radiological and clinical parameters were assessed during the follow-up period. Marginal bone did not change significantly during the follow-up period. The fine trabecular bone in intimate contact and enclosing the implant fixture was sufficient for successful osseointegration. None of the 14 implants were associated with compilations during the seven-year experimental period. This study suggests that dental implant procedures are a safe and reliable treatment option for restoration of missing dentition in patients with aplastic anemia.

• Journal of Biomedical Engineering Research
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• v.29 no.3
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• pp.212-221
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• 2008

The total hip replacement (THR) has been used as the most effective way to restore the function of damaged hip joint. However, various factors have caused some side effects after the THR. Unfortunately, the success of the THR have been decided only by the proficiency of surgeons so far. Hence, It is necessary to find the way to minimize the side effect caused by those factors. The purpose of this study was to suggest the definite data, which can be used to design and choose the optimal hip implant. Using finite element analysis (FEA), the biomechanical condition of bone cement was evaluated. Stress patterns were analyzed in three conditions: cement mantle, procimal femur and stem-cement contact surface. Additionally, micro-motion was analyzed in the stem-cement contact surface. The 3-D femur model was reconstructed from 2-D computerized tomography (CT) images. Raw CT images were preprocessed by image processing technique (i.e. edge detection). In this study, automated edge detection system was created by MATLAB coding for effective and rapid image processing. The 3-D femur model was reconstructed based on anatomical parameters. The stem shape was designed using that parameters. The analysis of the finite element models was performed with the variation of parameters. The biomechanical influence of each parameter was analyzed and derived optimal parameters. Moreover, the results of FE A using commercial stem model (Zimmer's V erSys) were similar to the results of stem model that was used in this study. Through the study, the improved designs and optimal factors for clinical application were suggested. We expect that the results can suggest solutions to minimize various side effects.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.2
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• pp.120-127
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• 2015

Purpose: The aim was to investigate the effect of implant thread designs on the stress dissipation of the implant. Materials and methods: The threads evaluated in this study included the V-shaped, buttress, reverse buttress, and square-shaped threads, which were of the same size (depth). Building four different implant/bone complexes each consisting of an implant with one of the 4 different threads on its cylindrical body ($4.1mm{\times}10mm$), a force of 100 N was applied onto the top of implant abutment at $30^{\circ}$ with the implant axis. In order to simulate different osseointegration stages at the implant/bone interfaces, a nonlinear contact condition was used to simulate immature osseointegration and a bonding condition for mature osseointegration states. Results: Stress distribution pattern around the implant differed depending on the osseointegration states. Stress levels as well as the differences in the stress between the analysis models (with different threads) were higher in the case of the immature osseointegration state. Both the stress levels and the differences between analysis models became lower at the completely osseointegrated state. Stress dissipation characteristics of the V-shape thread was in the middle of the four threads in both the immature and mature states of osseointegration. These results indicated that implant thread design may have biomechanical impact on the implant bed bone until the osseointegration process has been finished. Conclusion: The stress dissipation characteristics of V-shape thread was in the middle of the four threads in both the immature and mature states of osseointegration.

• The korean journal of orthodontics
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• v.44 no.5
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• pp.246-253
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• 2014

Objective: To evaluate the bioactivity, and the biomechanical and bone-regenerative properties of Ti6Al4V miniscrews subjected to anodization, cyclic precalcification, and heat treatment (APH treatment) and their potential clinical use. Methods: The surfaces of Ti6Al4V alloys were modified by APH treatment. Bioactivity was assessed after immersion in simulated body fluid for 3 days. The hydrophilicity and the roughness of APH-treated surfaces were compared with those of untreated (UT) and anodized and heat-treated (AH) samples. For in vivo tests, 32 miniscrews (16 UT and 16 APH) were inserted into 16 Wistar rats, one UT and one APH-treated miniscrew in either tibia. The miniscrews were extracted after 3 and 6 weeks and their osseointegration (n = 8 for each time point and group) was investigated by surface and histological analyses and removal torque measurements. Results: APH treatment formed a dense surface array of nanotubular TiO2 layer covered with a compact apatite-like film. APH-treated samples showed better bioactivity and biocompatibility compared with UT and AH samples. In vivo, APH-treated miniscrews showed higher removal torque and bone-to-implant contact than did UT miniscrews, after both 3 and 6 weeks (p < 0.05). Also, early deposition of densely mineralized bone around APH-treated miniscrews was observed, implying good bonding to the treated surface. Conclusions: APH treatment enhanced the bioactivity, and the biomechanical and bone regenerative properties of the Ti6Al4V alloy miniscrews. The enhanced initial stability afforded should be valuable in orthodontic applications.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.259-271
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• 2013

The purpose of this study was to make the stress distribution produced by simulated different load under two types of internal connection implant system (stepped and tapered type) by means of 3D finite element analysis, The finite element model was designed with the parallel placement of the one fixtures ($4.0mm{\times}11.5mm$) with reverse buttress thread on the mandibular 1st molar. Two models were loaded with 200 N magnitude in the vertical direction on the central position of the crown, the 1.5 mm and 3 mm buccal offset point from the central position of the fixture. The oblique load was applied at the angle of $30^{\circ}$ on the crown surface. Von Mises stress value was recorded and compared in the fixture-bone interface in the bucco-lingual dimension. The results were as follows; 1. The loading conditions of two internal connection implant systems (stepped and tapered type) were the main factor affecting the equivalent bone strain, followed by the type of internal connections. 2. The stepped model had more mechanical stability with the reduced max. stress compared to $11^{\circ}$ tapered models under the distributed oblique loading. 3. The more the contact of implant-abutment interface to the inner wall of implant fixture, the less stress concentration was reduced.

• Journal of Periodontal and Implant Science
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• v.51 no.5
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• pp.352-363
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• 2021

Purpose: Some systemic conditions, especially diabetes mellitus (DM), adversely affect dental implant success. This study aimed to investigate the effects of ibuprofen-loaded TiO₂ nanotube (ILTN) dental implants in alloxan-induced diabetic rabbits. Methods: Twenty-six New Zealand white rabbits were treated with alloxan monohydrate to induce DM. At 2 weeks following DM induction, 3 types of implants (sandblasted, large-grit, and acid-etched [SLA], ILTN, and machined) were placed into the proximal tibia in the 10 rabbits that survived following DM induction. Each type of implant was fitted randomly in 1 of the holes (round-robin method). The animals were administered alizarin (at 3 weeks) and calcein (at 6 weeks) as fluorescent bone markers, and were sacrificed at 8 weeks for radiographic and histomorphometric analyses. Results: TiO₂ nanotube arrays of ~70 nm in diameter and ~17 ㎛ in thickness were obtained, and ibuprofen was loaded into the TiO₂ nanotube arrays. A total of 26 rabbits were treated with alloxan monohydrate and only 10 rabbits survived. The 10 surviving rabbits showed a blood glucose level of 300 mg/dL or higher, and the implants were placed in these diabetic rabbits. The implant stability quotient (ISQ) and bone-to-implant contact (BIC) values were significantly higher in the ILTN group (ISQ: 61.8, BIC: 41.3%) and SLA group (ISQ: 62.6, BIC: 46.3%) than in the machined group (ISQ: 53.4, BIC: 20.2%), but the difference in the BIC percentage between the SLA and ILTN groups was not statistically significant (P=0.628). However, the bone area percentage was significantly higher in the ILTN group (78.0%) than in the SLA group (52.1%; P=0.000). Conclusions: The: ILTN dental implants showed better stability (ISQ) and BIC than the machined implants; however, these values were similar to the commercially used SLA implants in the 2-week diabetic rabbit model.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.2
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• pp.150-157
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• 2008

This study evaluated the influence of smooth and brushite-coated implant surfaces in dogs. The first through fourth mandibular premolars were extracted from eight young adult dogs. Twelve weeks after extraction. implantation was performed at the extraction sites. In total, 40 implant fixtures were implanted in the dog mandibles. Twenty machined implants served as controls and twenty brushite-coated surfaces served as tests. Dogs were sacrificed 2 and 4 weeks after implantation. The hemi-mandibles were obtained and processed histologically to obtain non-decalcified sections. Longitudinal sections of each implant were made and analyzed using light microscopy. The overall implant success rate was 83.3%. Histomorphometrically. the experimental group had a better percentage of bone-implant contact than the control group (p<0.05) and there was a significant difference between the 2- and 4-week groups after implantation (p<0.05) Our results suggest that the implant surface morphology influences the increase in peri-implant osteogenesis in the early period of peri-implant healing.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.3
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• pp.300-318
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• 2003

Statement of problem: The success of implants depends on intimate and direct contact of implant material on bone tissue and on functional relationship with soft tissue contact. Creation and maintenance of osseointegration depend on the understanding of the tissue's healing, repairing, and remodeling capacity and these capacities rely on cellular behavior. Altering the surface properties can modify cellular responses such as cell adhesion, cell motility, bone deposition, Therefore, various implant surface treatment methods are being developed for the improved bone cell responses. Purpose: The purpose of this study was to evaluate the responses of osteoblast-like cells to surface-modified titanium. Materials and Methods: The experiment was composed of four groups. Group 1 represented the electropolished surface. Group 2 surfaces were machined surface. Group 3 and Group 4 were anodized surfaces. Group 3 had low roughness and Group 4 had high roughness. Physicochemical properties and microstructures of the discs were examined and the responses of osteoblast-like cells to the discs were investigated. The microtopography was observed by SEM. The roughness was measured by three-dimension roughness measuring system. The microstructure was analyzed by XRD, AES. To evaluate cell responses to modified titanium surfaces, osteoblasts isolated from calvaria of neonatal rat were cultured. Cell count, morphology, total protein measurement and alkaline phosphatase activities of the cultures were examined. Results and Conclusion: The results were as follows 1. The four groups showed specific microtopography respectively. Anodized group showed grain structure with micropores. 2. Surface roughness values were, from the lowest to the highest, electropolished group, machined group, low roughness anodized group, and high roughness anodized group. 3. Highly roughened anodized group was found to have increased surface oxide thickness and surface crystallinity. 4. The morphology of cells, flattened or spherical, were different from each other. In the electropolished group and machined group, the cells were almost flattened. In two anodized groups, some cells were spherical and other cells were flattened. And the 14 day culture cells of all of the groups were nearly flattened due to confluency. 5. The number of attached cells was highest in low roughness anodized group. And the machined group had significantly lower cell count than any other groups(P<.05). 6. Total protein contents showed no difference among groups. 7. The level of alkaline phosphatase activities was higher in the anodized groups than electropolished and machined groups(P<.05).

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.2
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• pp.122-127
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• 2010

Purpose: The objective of this study was to investigate the effects of calcium phosphate coated titanium implant surface on bone response and implant stability at early stage of healing period of 3 weeks and later healing period of 6 weeks. Material and methods: A total of 24 machined, screw-shaped implants (Dentium Co., Ltd., Seoul, Korea) which dimensions were 3.3 mm in diameter and 5.0 mm in length, were used in this research. All implants (n = 24), made of commercially pure (grade IV) titanium, were divided into 2 groups. Twelve implants (n = 12) were machined without any surface modification (control). The test implants (n = 12) were anodized and coated with thin film (150nm) of calcium phosphate by electron-beam deposition. The implants were placed on the proximal surface of the rabbit tibiae. The bone to implant contact (BIC) ratios was evaluated after 3 and 6 weeks of implant insertion. Results: The BIC percentage of calcium phosphate coated implants ($70.8{\pm}18.9%$) was significantly higher than that of machined implants ($44.1{\pm}16.5%$) 3 weeks after implant insertion (P = 0.0264). However, there was no significant difference between the groups after 6 weeks of healing (P > .05). Conclusion: The histomorphometric evaluation of implant surface revealed that; 1. After 3 weeks early healing period, bone to implant contact (BIC) percentage of calcium phosphate coated implants (70.8%) was much greater than that of surface untreated machined implants (44.1%) with P = 0.0264. 2. After 6 weeks healing period, however, BIC percentage of calcium phosphate coated implants group (79.0%) was similar to the machined only implant group (78.6%). There was no statistical difference between two groups (P = 0.8074). 3. We found the significant deference between the control group and experimental group during the early healing period of 3 weeks. But no statistical difference was found between two groups during the later of 6 weeks.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.4
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• pp.301-311
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• 2011

Introduction: This study examined the effect of the application of low intensity pulsed ultrasound on bone healing after an injection of adipose tissue-derived stem cells (ADSCs) during the implantation of a titanium implant in the tibia of diabetes-induced rats. Materials and Methods: Twelve Sprague-Dawely rats were used. After inducing diabetes, the ADSCs were injected into the hole for the implant. Customized screw type implants, 2.0 mm in diameter and 3.5 mm in length, were implanted in both the tibia of the diabetes-induced rats. After implantation, LIPUS was applied with parameters of 3 MHz, 40 mW/$cm^2$, and 10 minutes for 7 days to the left tibiae (experimental group) of the diabetesinduced rats. The right tibiae in each rat were used in the control group. At 1, 2 and 4 week rats were sacrificed, and the bone tissues of both tibia were harvested. The bone tissues of the three rats in each week were used for bone-to-implant contact (BIC) and bone area (BA) analyses and the bone tissues of one rat were used to make sagittal serial sections. Results: In histomorphometric analyses, the BIC in the experimental and control group were respectively, $39.00{\pm}18.17%$ and $42.87{\pm}9.27%$ at 1 week, $43.74{\pm}6.83%$ and $32.27{\pm}6.00%$ at 2 weeks, and $32.62{\pm}11.02%$ and $47.10{\pm}9.77%$ at 4 weeks. The BA in experimental and control group were respectively, $37.28{\pm}3.68%$ and $31.90{\pm}2.84%$ at 1 week, $20.62{\pm}2.47%$ and $15.64{\pm}2.69%$ at 2 weeks, and $11.37{\pm}4.54%$ and $17.69{\pm}8.77%$ at 4 weeks. In immunohistochemistry analyses, Osteoprotegerin expression was strong at 1 and 2 weeks in the experimental group than the control group. Receptor activator of nuclear factor kB ligand expression showed similar staining at each week in the experimental and control group. Conclusion: These results suggest that the application of low intensity pulsed ultrasound after an injection of adipose tissue-derived stem cells during the implantation of titanium implants in the tibia of diabetes-induced rats provided some positive effect on bone regeneration at the early stage after implantation. On the other hand, this method is unable to increase the level of osseointegration and bone regeneration of the implant in an uncontrolled diabetic patient.