• Imaging Science in Dentistry
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• v.41 no.2
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• pp.59-62
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• 2011

Purpose : This study was performed to evaluate the changes of jaw bone density around the dental implant after placement using computed tomography scan (CT-Scan). Materials and Methods : This retrospective study consisted of 30 patients who had lost 1 posterior tooth in maxilla or mandible and installed dental implant. The patients took CT-Scan before and after implant placement. Hounsfield Unit (HU) was measured around the implants and evaluated the difference of HU before and after implant installation. Results : The mean HU of jaw bone was 542.436 HU and 764.9 HU before and after implant placement, respectively (p<0.05). The means HUs for male were 632.3 HU and 932.2 HU and those for female 478.2 HU and 645.5 HU before and after implant placement, respectively (p<0.05). Also, the jaw bone with lower density needed longer period for implant procedure and the increased change of HU of jaw bone was less in the cases which needed longer period for osseointegration. Conclusion : CT-Scan could be used to assess the change of bone density around dental implants. Bone density around dental implant was increased after placement. The increased rate of bone density could be determined by the quality of jaw bone before implant placement.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.1
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• pp.165-180
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• 1997

The purpose of this study was to observe bone apposition and marginal bone loss and to check the possibility of success on titanium implant, HA coated implant and the implant with natural coral that were place immediately after teeth extraction in dogs. Experimental subjects were divided into 4 groups ; the 1st group is the titanium implant, second the HA coated implant, third the implant with natural coral, and the last the control group that was prepared in the extraction sockets. After 12 weeks, the dogs were sacrificed for visual observation and microscopic examination approaching histologic and histomorphometric analysis. The results were as follows : 1. Neither the infection nor the exposure of implant was found at the sites of all implant. 2. In a histomorphometric analysis, mean percentage of direct bone contact with the titanium implant was 80.7% and the HA coated implant showed 81.5% apposition, but the implant with natural coral showed 64.9% apposition(P<0.05). 3. In a microscopic examination, mature lamellated bone was found around the immediate implants and control group, while unabsorbed natural coral around the immediate implants with natural coral was found. 4. All immediate implant groups showed the loss of marginal bone in order from implant with natural coral, titanium implant, and HA coated implant. 5. Implant with natural coral that was placed by the type I interface of the Barzilay's classification immediately after teeth extraction showed low percentage of direct bone contact area, low success rate and a lot of marginal bone loss. Above results suggested that the immediate implants are osseointegrated successfully, although slightly marginal bone was loss.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.3
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• pp.455-469
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• 1994

Regular radiographic examination has been considered an essential diagnositic method for osseointegrated dental implantation. This study investigated marginal bone loss through the measurement on periapical radiographs and changes in bone density through digital subtraction image radiographic method around 88 endoseous root-form dental implants in 43 human subjects. Four types of endosseous dental implants were investigated : Standard series, Mini series and Hex-lock system of Steri-Oss Dental implant system, and $Br{\aa}nemark$-type implant from 3i dental implant system, in a 3 month interval for a total period of 12 months. The results were as follows : 1. Rapid bone loss occurred in the first 3 months in all 4 groups, and the bone level stabilized at the first thread of the implant fixtures. Amount of bone loss for 12 months showed correlation with the length of the polished neck portion. 2. Most of the implant systems showed resorption of alveolar bone up to the polished neck portion although a long polished neck could delay the resolution. 3. Alveolar bone loss apical to the polished neck portion stabilized at the first thread of the fixtures with no correlation to either the time of exposure of the polished neck or types of implant systems. 4. No changes in bone density around the implant threads were observed throughout the experimental period. Bone density decreased at the marginal bone, and increased at the newly-formed alveolar crest. These results indicate that most of the alveolar bone loss occur within the first 12 months after installation of endosseous root-form dental implants resulting in the exposure of polished neck portions, and the bone level stabilizes thereafter at the first thread portions of the implant fixtures. The experimental period of 12 months seems insufficient for observing changes in bone density, and a long-term observation should be needed.

• Journal of Periodontal and Implant Science
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• v.35 no.2
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• pp.383-399
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• 2005

The successful implantation necessitate tissue regeneration m site of future implant placement, there being severe bone defect. Therapeutic approaches to tissue regeneration in the site have used bone grafts, root surface treatments, barrier membranes, and growth factors, the same way being applied to periodontal tissue regeneration. Great interest in periodontal tissue regeneration has lead to research in bone graft, guided-tissue regeneration, and the administration of growth factors as possible means of regenerating lost periodontal tissue. The blood component separated by centrifuging the blood is the platelet-rich plasma. There are growth factors, PDGF, $TGF{beta}1$, $TGF{beta}2$ and IGF in the platelet-rich plasma. The purpose of this study was to study the histopathological correlation between the use of platelet-rich plasma and the healing of bone defect around implant fixture site. Implant fixtures were inserted and graft materials were placed into the left femur of in the experimental group, while the control group received only implant fixtures. In the first experimental group, platelet-rich plasma and BBP xenograft were placed at the implant fixture site, and the second experimental group had platelet-rich plasma, BBP xenograft, and the e-PTFE membrane placed at the fixture site. The degree of bone regeneration adjacent to the implant fixture was observed and compared histopathologically at 2, 4, and 8 weeks after implant fixture insertion. The results of the experiment were as follows: 1. Bone remodeling in acid etched surface near the implant fixture of all experimental groups was found to be greater than new bone formation. 2. Bone remodeling in acid etched surface distant to the implant fixture of all experimental groups was decreased and new bone formation was not changed. 3. Significant new bone formation in machined surface near the implant fixture of bothl experimental groups was observed in 2 weeks. 4. New bone formation in machined surface distant to the implant fixture of both experimental groups was observed. Bone remodeling was significant in near the implant fixture and not in distant to the implant fixture. The results of the experiment suggested that the change of bone formation around implant. Remodeling in machined surface distant to the implant fixture of both experimental groups, and new bone formation and remodeling near the implant fixture were significant.

• Advances in biomechanics and applications
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• v.1 no.2
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• pp.95-109
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• 2014

Peri-acetabular bone ingrowth plays a crucial role in long-term stability of press-fit acetabular cups. A poor bone ingrowth often results in increased cup migration, leading to aseptic loosening of the implant. The rate of peri-prosthetic bone formation is also affected by the polar gap that may be introduced during implantation. Applying a mechano-regulatory tissue differentiation algorithm on a two-dimensional plane strain microscale model, representing implant-bone interface, the objectives of the study are to gain an insight into the process of peri-prosthetic tissue differentiation and to investigate its relationship with implant-bone relative displacement and size of the polar gap. Implant-bone relative displacement was found to have a considerable influence on bone healing and peri-acetabular bone ingrowth. An increase in implant-bone relative displacement from $20{\mu}m$ to $100{\mu}m$ resulted in an increase in fibrous tissue formation from 22% to 60% and reduction in bone formation from 70% to 38% within the polar gap. The increase in fibrous tissue formation and subsequent decrease in bone formation leads to weakening of the implant-bone interface strength. In comparison, the effect of polar gap on bone healing and peri-acetabular bone ingrowth was less pronounced. Polar gap up to 5 mm was found to be progressively filled with bone under favourable implant-bone relative displacements of $20{\mu}m$ along tangential and $20{\mu}m$ along normal directions. However, the average Young's modulus of the newly formed tissue layer reduced from 2200 MPa to 1200 MPa with an increase in polar gap from 0.5 mm to 5 mm, suggesting the formation of a low strength tissue for increased polar gap. Based on this study, it may be concluded that a polar gap less than 0.5 mm seems favourable for an increase in strength of the implant-bone interface.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.6
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• pp.575-579
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• 2006

Purpose : The purpose of this study was to evaluate peri-implant bone loss and implant success on anterior maxillary alveolar ridges and Compare Class III and Class IV ridges in the aspect of peri-implant bone loss. Material and Methods : 14 patients (aged 21 to 68, 6males and 8females), who lacked maxillary anterior teeth and were installed from January 2000 to April 2003 at Samsung Medical Center, were selected. The type of implant used included 30 $Br\ddot{a}nemark$ implant. They were taken with digital tomographic and conventional intraoral radiographic examinmation, and were treated with implant installaion without bone augmentation. The peri-implant bone resorption was measured at the mesial and distal aspect of implant on the conventional intraoral radiographs. Results : The study classified the anterior maxillary alveolar ridge and measured peri-implant bone resorption from the period of implant installation to the 2nd year after functional loading radiographically. The study revealed no statistically significant difference between two groups, which was classified by its morphology. The average bone resorption on healing period before loading was 0.18mm and 0.18mm, the 1st year of loading period, 0.77 mm and 0.84mm, and on the 2nd year of loading period, 0.07mm and 0.06mm, respectively on both Class III and class IV. Conclusion : In the knife edge form of anterior maxillary residual ridges(Class IV), implant placement without ridge augmentation does not have significant difference with that of Class III alveolar ridge in the concern of Implant success after 2 year functional loading period in the aspect of peri-implant bone resorption radiographically.

• The Journal of Advanced Prosthodontics
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• v.3 no.1
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• pp.10-15
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• 2011

PURPOSE. This study investigated the influence of bone quality and surgical technique on the implant stability quotient (ISQ) value. In addition, the influence of interfacial bone quality, directly surrounding the implant fixture, on the resonance frequency of the structure was also evaluated by the finite element analysis. MATERIALS AND METHODS. Two different types of bone (type 1 and type 2) were extracted and trimmed from pig rib bone. In each type of bone, the same implants were installed in three different ways: (1) Compaction, (2) Self-tapping, and (3) Tapping. The ISQ value was measured and analyzed to evaluate the influence of bone quality and surgical technique on the implant primary stability. For finite element analysis, a three dimensional implant fixture-bone structure was designed and the fundamental resonance frequency of the structure was measured with three different density of interfacial bone surrounding the implant fixture. RESULTS. In each group, the ISQ values were higher in type 1 bone than those in type 2 bone. Among three different insertion methods, the Tapping group showed the lowest ISQ value in both type 1 and type 2 bones. In both bone types, the Compaction groups showed slightly higher mean ISQ values than the Self-tapping groups, but the differences were not statistically significant. Increased interfacial bone density raised the resonance frequency value in the finite element analysis. CONCLUSION. Both bone quality and surgical technique have influence on the implant primary stability, and resonance frequency has a positive relation with the density of implant fixture-surrounding bone.

• Journal of Periodontal and Implant Science
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• v.49 no.3
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• pp.185-192
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• 2019

Purpose: Implant wall thickness and the height of the implant-abutment interface are known as factors that affect the distribution of stress on the marginal bone around the implant. The goal of this study was to evaluate the long-term effects of supracrestal implant placement and implant wall thickness on maintenance of the marginal bone level. Methods: In this retrospective study, 101 patients with a single implant were divided into the following 4 groups according to the thickness of the implant wall and the initial implant placement level immediately after surgery: 0.75 mm wall thickness, epicrestal position; 0.95 mm wall thickness, epicrestal position; 0.75 mm wall thickness, supracrestal position; 0.95 mm wall thickness, supracrestal position. The marginal bone level change was assessed 1 day after implant placement, immediately after functional loading, and 1 to 5 years after prosthesis delivery. To compare the marginal bone level change, repeated-measures analysis of variance was used to evaluate the statistical significance of differences within groups and between groups over time. Pearson correlation coefficients were also calculated to analyze the correlation between implant placement level and bone loss. Results: Statistically significant differences in bone loss among the 4 groups (P<0.01) and within each group over time (P<0.01) were observed. There was no significant difference between the groups with a wall thickness of 0.75 mm and 0.95 mm. In a multiple comparison, the groups with a supracrestal placement level showed greater bone loss than the epicrestal placement groups. In addition, a significant correlation between implant placement level and marginal bone loss was observed. Conclusions: The degree of bone resorption was significantly higher for implants with a supracrestal placement compared to those with an epicrestal placement.

• Journal of Periodontal and Implant Science
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• v.36 no.2
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• pp.531-554
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• 2006

Oral implants must fulfill certain criteria arising from special demands of function, which include biocompatibility, adequate mechanical strength, optimum soft and hard tissue integration, and transmission of functional forces to bone within physiological limits. And one of the critical elements influencing the long-term uncompromise functioning of oral implants is load distribution at the implant- bone interface, Factors that affect the load transfer at the bone-implant interface include the type of loading, material properties of the implant and prosthesis, implant geometry, surface structure, quality and quantity of the surrounding bone, and nature of the bone-implant interface. To understand the biomechanical behavior of dental implants, validation of stress and strain measurements is required. The finite element analysis (FEA) has been applied to the dental implant field to predict stress distribution patterns in the implant-bone interface by comparison of various implant designs. This method offers the advantage of solving complex structural problems by dividing them into smaller and simpler interrelated sections by using mathematical techniques. The purpose of this study was to evaluate the stresses induced around the implants in bone using FEA, A 3D FEA computer software (SOLIDWORKS 2004, DASSO SYSTEM, France) was used for the analysis of clinical simulations. Two types (external and internal) of implants of 4.1 mm diameter, 12.0 mm length were buried in 4 types of bone modeled. Vertical and oblique forces of lOON were applied on the center of the abutment, and the values of von Mises equivalent stress at the implant-bone interface were computed. The results showed that von Mises stresses at the marginal. bone were higher under oblique load than under vertical load, and the stresses were higher at the lingual marginal bone than at the buccal marginal bone under oblique load. Under vertical and oblique load, the stress in type I, II, III bone was found to be the highest at the marginal bone and the lowest at the bone around apical portions of implant. Higher stresses occurred at the top of the crestal region and lower stresses occurred near the tip of the implant with greater thickness of the cortical shell while high stresses surrounded the fixture apex for type N. The stresses in the crestal region were higher in Model 2 than in Model 1, the stresses near the tip of the implant were higher in Model 1 than Model 2, and Model 2 showed more effective stress distribution than Model.

• Journal of Periodontal and Implant Science
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• v.37 no.3
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• pp.535-542
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• 2007

Background : Repeated dis/re-connection of implant abutment caused bone loss around implant fixtures due to the new formation of biologic width of the mucosal-implant barrier. The aim of this clinical study was to evaluate whether the repeated dis/re-connection of implant abutment cause bone loss clinically and the effect of cleansing methods on a bone loss during the early healing period. Methods : A total 50 implants were installed in 20 patients and repeated dis/re-connection of abutment was performed at the time of surgery and once per week for 12 weeks. 0.9% normal saline solution as group1 and 0.1% chlorhexidine solution as group 2 was used to clean abutments. All patients had radiographs taken at the placement of implant and 4, 8, and 12 weeks postoperatively. The data for bone loss around implant were analyzed. Results: The marginal bone loss at 12 weeks were $1.28{\pm}0.51mm$, $1,32{\pm}0,57mm$ in the mesial and distal sides in group1, $1.94{\pm}0.75mm$, $1.81{\pm}0.84mm$ in group 2, respectively. In view of marginal bone loss, there was not a significant statistical difference between groups. Conclusions : Repeated dis/re-connection of implant abutment may not cause marginal bone loss around implant fixture although limited samples and short-term observation period. In spite of more bone loss in group 2, there was no statistical significant difference between groups. In context of those results, the clinical significance of the repeated dis/re-connection of implant abutment and the cleansing method of abutments is debatable when it comes to marginal bone loss during early healing period.