• The Journal of Advanced Prosthodontics
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• v.1 no.3
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• pp.140-144
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• 2009

STATEMENT OF PROBLEM. Little information is available about the buccal gingival level of multiple implant restorations. PURPOSE. This study was aimed to evaluate the relationship between width and height of buccal soft tissue around single and 2 adjacent implant restorations. MATERIAL AND METHODS. Four implant restoration groups (first and second molars, single second molars, posterior single restorations between teeth, and anterior single restorations between teeth) were randomly chosen from one dental institute. Each group comprised of 6 patients. After 6 months of function, silicone impressions were taken and stone models were fabricated for each restoration group. The stone models were cut in bucco-lingual direction at the most apical point of buccal gingival margin. The height and width of buccal supra-implant soft tissue were measured. One way ANOVA and Tukey HSD post hoc tests were performed to analyze the data obtained (P < .05). RESULTS. The most unfavorable width-height ratio was noted for the group, which was comprised of the second molar in the multiple adjacent (first and second molar) implant-supported restorations. The group also resulted in the shorter height of buccal supra-implant mucosa rather than that of anterior single implant restorations between natural teeth. CONCLUSION. To achieve a favorable level of buccal gingival margin, greater thickness of buccal supra-implant mucosa is required for the implant restorations without a neighboring natural tooth compared to the implant restorations next to a natural tooth.

• Archives of Plastic Surgery
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• v.44 no.4
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• pp.344-347
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• 2017

Preservation of the breast skin envelope during immediate implant-based breast reconstruction is important for producing symmetrical and natural-looking breasts. We propose the lazy S design for the closure of round-shaped wounds with the hope of improving the aesthetic outcomes and reducing the tension on the wound by preserving the skin. Additionally, the direction of tension is dispersed due to the shape of this design. Patients undergoing implant reconstruction after skin-sparing mastectomy may benefit from the lazy S design.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.644-652
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• 2007

Statement of problem: Resonance frequency analysis is evaluated as the non-invasive and objective method for the evaluation of implant stability and has been increasingly used. It is necessary to evaluate the factors affect the ISQ measurement stability. Purpose: This study was performed to evaluate the effect of the autoclave sterilization and reuse of $Smartpeg^{TM}$ on ISQ measurement. Material and methods: $SmartPeg^{TM}$ (Integration Diagnostics Ltd., $G\ddot{o}teborg$, Sweden) of autoclave group (A) was autoclave sterilized 9 times and $Smartpeg^{TM}$ of reuse group (R) was reused 9 times. Ten $SmartPeg^{TM}s$ were allocated to each group and after each autoclave sterilization and reuse, implant stability quotient (ISQ) values were measured 3 times from the two directions a and b at a right angle. $Osstell^{TM}$ mentor (Integration Diagnostics Ltd. $G\ddot{o}teborg$, Sweden) was used and type 1 (article no. 100353) $Smartpeg^{TM}$ was selected according to $Smartpeg^{TM}$ reference list. Osstem Implant US II future (Osstem Co., Seoul, Korea) in $4.0mm{\times}11.5mm$ was embedded in the self-curing acrylic resin ($Orthojet^{(R)}$, Lang Dental, U.S.A.). Data was statistically analyzed by one-way ANOVA $({\alpha}=.05)$ and scheffe test was done where a significant difference exist. Correlation test was also done between ISQ value and the number of autoclave sterilization or reuse. Results: 1. In autoclave group, the means and sd. of ISQ value before autoclave sterilization were $84.97{\pm}0.41,\;84.93{\pm}0.74$ at direction a and b. There was significant differences between autoclave groups at direction a and b (P=.000). 2. In reuse group, the means and sd. of ISQ value before reuse were $85.40{\pm}0.62,\;85.50{\pm}0.57$ at direction a and b. There was no significant difference between reuse groups at direction a and b (P>.05). 3. There was a weak positive correlation between the number of reuse and ISQ value at direction a and b (${\gamma}=.207$ and .246, P<.01). Conclusion: Within the limitations of this study, the following conclusions were drawn. Till ninth reuse of $Smartpeg^{TM}$, the ISQ measurement stability did not be affected. After twice autoclave sterilization of $Smartpeg^{TM}$ the ISQ measurement stability was affected.

• The Journal of Advanced Prosthodontics
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• v.7 no.2
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• pp.115-121
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• 2015

PURPOSE. This study aimed to evaluate the effect of implant thread depth on primary stability in low density bone. MATERIALS AND METHODS. The insertion torque was measured by inserting Ti implants with different thread depths into solid rigid polyurethane blocks (Sawbones) with three different bone densities ($0.16g/cm^3$, $0.24g/cm^3$, and $0.32g/cm^3$). The insertion torque value was evaluated with a surgical engine. The static compressive strength was measured with a universal testing machine (UTM) and the Ti implants were aligned at $30^{\circ}$ against the loading direction of the UTM. After the static compressive strength test, the Ti implants were analyzed with a Measurescope. RESULTS. The Ti implants with deeper thread depth showed statistically higher mean insertion torque values (P<.001). Groups A and group B had similar maximum static compressive strengths, as did groups C and D (P>.05). After the static compressive strength, the thread shape of the Ti implants with deeper thread depth did not show any breakage but did show deformation of the implant body and abutment. CONCLUSION. The implants with deeper thread depth had higher mean insertion torque values but not lower compressive strength. The deep threads had a mechanical stability. Implants with deeper thread depth may increase the primary stability in areas of poor quality bone without decreasing mechanical strength.

• Journal of Technologic Dentistry
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• v.42 no.4
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• pp.348-354
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• 2020

Purpose: Zirconia is differentiated from other ceramics because of its high resistance to corrosion and wear, excellent flexural strength (900~1400 MPa), and high hardness. Dental zirconia with proven mechanical/biological stability is suitable for the manufacture of implants. However, there are limited in vivo studies evaluating stress distribution in zirconia compared with that in titanium implants and studies analyzing finite elements. This study was conducted to evaluate the stress distribution of the supporting bone surrounding zirconia and titanium implants using the finite element analysis method. Methods: For finite element analysis, a single implant-supported restoration was designed. Using a universal analysis program, eight occlusal points were set in the direction of the occlusal long axis. The occlusal load was simulated at 700 N. Results: The zirconia implant (47.7 MPa) von Mises stress decreased by 5.3% in the upper cortical bone compared with the titanium implant (50.2 MPa) von Mises stress. Similarly, the zirconia implant (20.8 MPa) von Mises stress decreased by almost 4% in the cancellous bone compared with the titanium implant (21.7 MPa) von Mises stress. The principal stress in the cortical and cancellous bone exhibited a similar propensity to von Mises stress. Conclusion: In the supporting bone, the zirconia implant is able to reduce bone resorption caused by mechanically transferred stress. It is believed that the zirconia implant can be a potential substitute for the titanium implant by reinforcing aesthetic characteristics and improving stress distribution.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.3
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• pp.176-182
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• 2020

Purpose: To evaluate the effects of load direction, number of implants, and alignment of implant position on stress distribution in implant, prosthesis, and bone tissue. Materials and Methods: Four 3D models were made to simulate posterior mandible bone block: two implants and 3-unit fixed dental prosthesis (FDP) with a pontic in the center (model M1), two implants and 3-unit FDP with a cantilever pontic at one end (model M2), FDP supported by three implants with straight line placement (model M3) and FDP supported by three implants with staggered implant configuration (model M4). The applied force was 120 N axially or 120 N obliquely. Results: Peak von Mises stresses caused by oblique occlusal force were 3.4 to 5.1 times higher in the implant and 3.5 to 8.3 times higher in the alveolar bone than those stresses caused by axial occlusal force. In model M2, the connector area of the distal cantilever in the prosthesis generated the highest von Mises stresses among all models. With the design of a large number of implants, low stresses were generated. When three implants were placed, there were no significant differences in the magnitude of stress between staggered arrangement and straight arrangement. Conclusion: The effect of staggering alignment on implant stress was negligible. However, the number of implants had a significant effect on stress magnitude.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.2
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• pp.296-326
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• 1994

The purpose of this study was to evaluate the mechanical effects when one implant fixture was connected to the natural teeth with reduced alveolar bone height. This study also examined the effects of increasing the number of abutment teeth and the effects of the intramobile connector and the titanium connector as they were inserted between the implant superstructure and the fixture. The distribution and concentration load was applied to the fixed partial denture(FPD) supported by implant and the natural teeth with reduced alveolar bone height. The stress and displacement of each element was observed and compared by the two-dimensional finite element method. The following results were obtained : 1. The greater the loss of alveolar bone in natural teeth area, the greater the displacement of FPD and the stress concentration in alveolar bone around implant, especially at the stress concentration in the mesial alveolar bone crest around implant fixture. 2. The displacement of FPD was increased more and that of implants fixture was decreased more when intramobile connector was used than titanium connector was used. Also the stress concentration in alveolar bone around implant fixture was greater when intramobile connector than titanium connector. One implication of this finding was that the difference in stiffness of implant and the natural teeth with reduced alveolar bone height could be partially compensated in case of the POM intramobile connector. 3. The amount and direction of displacement and the stress distribution of the 4-unit FPD was better than those of the 3-unit FPD. It implied that the difference of stiffness of implant and natural teeth with reduced alveolar bone height could be partially compensated in case of the 4 unit FPD.

• Journal of Periodontal and Implant Science
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• v.25 no.2
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• pp.418-437
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• 1995

The effect of the hydroxyapatite coatings on Titanium implants has been the subject of recent investigations. So far, the use of HA coating remains substantially controversial.This study was aimed to evaluate histologically the bone healing patterns around titanium plasm sprayed(TPS) amd HA-coated implant after implantation into the femur neck of ten adult dogs. After implantation, animals were sacrificed at the intervals of 2,4,6,8 and 12 weeks.The fluorescent dyes were injected on the postoperative 4th and 12th week into the animals supposed to be killed at the 12th week. The morphology and direction of new bone formation was similar in both TPS and HA-coated implants.There was a tendency toward more bone formation in the cortical bone area than in the cancellous bone area. Histologically,in the interface of the HA-coated implants, bone response and bone maturation was faster, compared to the TPS implants in the 2nd and 4th week. By fluorescent microscopy, new bone formation was active in the 4th week around both implants and was directed from the periosteum overlying cortical bone to the cancellous bone. These results suggest that the bone formation and maturation is faster during the early healing stage in the interface of the HA-coated implant and where the cortical bone quality is poor, HA coated implant is superior to the TPS implant in the early phase of new bone formation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.39 no.3
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• pp.144-147
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• 2013

Damage to adjacent teeth is one of the various complications that may occur during implant placement and is often the result of improper direction during fixture placement or excessive depth of placement. In general, if detrimental symptoms, such as reaction to percussion in damaged teeth, mobility, and pulp necrosis, are not present, osseointegration should be observed at follow-up. In three cases, the possibility of root damage due to an implant fixture placed too close to each adjacent tooth was perceived on radiographs. However, in all of these cases, there were no clinical symptoms or radiographic changes present in the tooth, and the implants did not exhibit decreased stability or peri-implantitis. Therefore, we can carefully predict that the implant fixture close to the adjacent tooth did not invade the cementum of the root, and therefore did not produce the suspected pulpal damage or periradicular symptoms. In this study, we considered both the implant status as well as the adjacent tooth.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.1
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• pp.55-74
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• 2006

The external contour of an implant can have significant effects on the load transfer characteristics and may result in different bone failure rates for different implant system. The purpose of this study was to investigate the effects of crest module shape and occlusal load direction on bone failure modes of five commercially available dental implant systems. Five different implant systems with internal connection; ITI (Model 1), Astra (Model 2), Bicon (Model 3), Friadent (Model 4), and Paragon (Model 5), comparable in size, but different in thread profile and cest module shapes, were compared using the finite element method. Conclusively, in the internal connection system of the implant-abutment connection methods, the stress-induced pattern at the supporting bone according to the abutment connection form had differenence among them, and implants with narrowing crestal module cross-sections at the top of the cortical bone created more favorable load transfer characteristics in this region. But it is considered that the future study is necessary about how this difference in the magnitude of the stress have an effect on the practical clinic.