• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.139-155
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• 2009

Objective : To assess the biological stability of immediate transmucosal placement of tapered implants into tooth extraction sockets. Material and methods : Following tooth extraction, tapered implants were immediately placed into the sockets. Teeth with evidence of acute periapical pathology were excluded. After implant placement, sutured allowing a non-submerged, transmucosal healing. Standardized radiographs were obtained every visiting from baseline to 32 weeks after implant placment. Changes in depth of the distance from the implant shoulder (IS) and from the alveolar crest (AC) to the bottom of the defect (BD) were assessed. Results : Thirteen patients (10 males and 3 females) were enrolled and followed. They contributed with 15 tapered implants. extraction iste displayed sufficient residual bone volume to allow primary stability of all implants. The mean surgery time was $41{\pm}10.0$ mins. All implants healed uneventfully yielding a survival rate of 100%. Mean ISQ values were relatively stable. Interproximal crestal bone decreased $1.69{\pm}1.2mm$ (mesial), $1.65{\pm}1.2mm$ (distal) from baseline to 32-week follow-up. No statistically significant changes with respect to FMPS, FMBS, PPD and width of KG were observed. Conclusions: Immediate transmucosal implant placement represented a predictable treatment option for the replacement of teeth lost due to reasons including fractures, endodontic failures and caries.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.1
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• pp.25-39
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• 2011

In animal studies, Magnesium (Mg) - incorporated oxidized implants showed significant enhancement of the bone response. This prospective clinical trial was performed to investigate the success rate, implant stability and marginal bone loss of Mg oxidized clinical implant. The experimental protocol was approved by Institutional Review Board of the Gangneung-Wonju National University Dental Hospital. Fifty healthy patients had partial edentulism were included in this study. Mg oxidized clinical implants (Implant M, Shinhung, Korea) were installed and restored with conventional protocol. The patients were recalled at 1, 3, 6 months after functional loading. Implant stability quotient (ISQ) was measured and periapical radiographic images were obtained. Amount of marginal bone loss was calculated with calibrated images from periapical radiographs. Repeated measured analysis of variance and post hoc Tukey test were used to compare the mean ISQ and bone level. A total of 101 implants were analyzed. The mean ISQ values increased continuously with time lapse from 68.4 at fixture installation to 71.5 at 6 months after loading. Implant stability was correlated with gender, fixture diameter, bone quality and implant sites. The mean marginal bone loss during 6 months after loading was 0.26 mm. There was no failed implant and six-month success rate was 100%. Within the limitations of this study, the six-month success rate of Mg oxidized implant was satisfactory. The implant stability and marginal bone level were excellent. However, further longer clinical studies will be needed to confirm the success of Mg oxidized clinical implant.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.70-79
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• 2020

Purpose: The purpose of this study was to evaluate the effect of attachments and palatal coverage on stress distribution in maxillary implant overdenture using finite element analysis. Materials and Methods: Four maxillary overdenture 3-D models with four implants placed in the anterior region were fabricated with computer-aided design. 1) Ball-F: Non-splinted ball attachment and full palatal coverage, 2) Ball-P: Non-splinted ball attachment and U-shaped partial palatal coverage, 3) Bar-F: Splinted milled bar attachment and full palatal coverage, 4) Bar-P: Splinted milled bar attachment and U-shaped partial palatal coverage. Stress distribution analysis was performed with ANSYS workbench 14. 100 N vertical load was applied at the right first molar unilaterally and maximum stress was calculated at the implant, peri-implant bone and mucosa. Results: The use of the ball attachment showed lower maximum stress on implant and peri-implant bone than the use of the milled bar attachment. But it showed contrary tendency in the mucosa. Regardless of attachment, full palatal coverage showed lower maximum stress on implant, peri-implant bone and mucosa. Conclusion: Within the limitation of this study, ball attachment improved stress distribution on implant and peri-implant bone rather than milled bar attachment in maxillary implant overdenture. Also, full palatal coverage is more favorable in stress distribution.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.1
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• pp.67-76
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• 2008

Implant requires long lasting, strong osseointegration using bio-mechanical interlocking by bone ingrowth. In regarding the size level for bone ingrowth, the micro-patterning would enhance bone response. Micro-patterning can increase the area contacting the bone tissues. Therefore, it may distribute the load to the surrounding bone tissue, more effectively. This study compared and analyzed the load distributing effect with the shape and number of micro-patterning. For the optimal comparison of threads, the assumptions different from general finite element analysis model were made. It was assumed that the implant was axisymmetric and infinitely long. The implant was assumed to be completely embedded in the infinitely long cortical bone and to have 100% bone apposition. The implant-bone interface had completely fixed boundary conditions and received an infinitely big axial load. The condition of threads were as follows. The reference model 1 had conventional thread. Model 2 had 2 micro-patterns on the upper flank of the thread. Model 3 had 2 micro-patterns on the lower flank of the thread. Model 4 had 2 micro-patterns on the upper and lower flanks of the thread. Model 5 had 3 micro patterns on the upper and lower flanks of the thread. The results were as follows: 1. The thread with micro-patterns distributed stress better than the conventional thread. 2. The thread with micro-patterns on the lower flank distributed stress better than that with micro-patterns on the upper flank. 3. The thread with 3 micro-patterns distributed stress better than that with 2 micro-patterns, However, an area with stress concentration occurred.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.1
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• pp.11-21
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• 2013

The purpose of this study was to get a proper time when implant was loaded and superstructure was fabricated by tracing a change of the implant stability in bone type for 1 year. We carried out RFA(resonance frequency analysis) of 67 implants in 36 patients at the time of surgery, 2, 6, 10, 14weeks, and 1year postoperatively for each implant, and analyzed data for different bone density. The ISQ value at the time of 10 & 14weeks postoperatively were significant(P<0.01) in subjective grouping, while that were not significant in objective grouping(P>0.05). The change pattern of ISQ value could be expressed $y=y_0+a{\times}\{1-\exp(-b{\times}x)\}$ for 1 year in this study, ISQ value at surgery might be used to estimate the time of superstructure fabrication consequentially.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.2
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• pp.114-118
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• 2017

Purpose: The aim of this study was to investigate the effects of a titanium component for the zirconia abutment in the internal connection implant system on screw loosening under thermocycling conditions. Materials and Methods: Internal connection titanium abutments and external connection zirconia abutments with titanium sockets were connected respectively to screw-shaped internal connection type titanium implants with 30 Ncm tightening. These implant-screw-abutment assemblies were divided into two groups of five specimens each; titanium abutments as control and zirconia abutments with titanium sockets as experimental group. The specimens were subjected to 2,000 thermocycles in water baths at $5^{\circ}C$ and $55^{\circ}C$, with 60 seconds of immersion at each temperature. The removal torque values (RTVs) of the abutment screws of the specimen were measured before and after thermocycling. RTVs pre- and post-thermocycling were investigated in statistics. Results: There was not screw loosening identified by tactile and visual inspection in any of the specimens during or after thermocycling. The mean RTV difference for the control group and the experimental group were $-1.34{\pm}2.53Ncm$ and $-1.26{\pm}2.06Ncm$, respectively. Statistical analysis using an independent t-test revealed that no significant differences were found in the mean RTV difference of the groups (P > 0.05). Conclusion: Within the limitations of this in vitro study, the titanium socket for the zirconia abutment did not show a significant effect on screw loosening under thermal stress compared to the titanium abutment in the internal connection implant.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.1
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• pp.29-40
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• 2020

Purpose: The purpose of this study was to compare the accuracy of impression taking method using the encoded healing abutment, scan body and pick-up impression coping with different implant angulations. Materials and Methods: Master model was fabricated by 3D printer and three implants were placed into the model with 0°, 10° and 20° mesial angulation. The abutments were secured to each implants and master model was scanned to make a reference model. Group P model was fabricated using pick-up impression copings and model was scanned after securing the abutments. Encoded healing abutment (Group E) and scan body (Group S) were secured on the master model and digital impression was taken using intraoral scanner 15 times each. Each STL files of test groups were superimposed with reference model using best fit alignment and root mean square (RMS) value was analyzed. Results: The RMS values were lowest in Group P, followed by Group S and Group E. Group P showed significant difference with Group S and E (P < 0.05) while there was no significant difference between Group S and E. Correlation between implant angulation and RMS value was significant in Group E (P < 0.05). Conclusion: The pick-up impression coping method showed higher accuracy and there was no significant difference in accuracy between the healing abutment and the scan body. The clinical use of the encoded healing abutment is possible, but it should be used with caution in the case of angulated implant.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.1
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• pp.47-54
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• 2017

The atrophy of edentulous ridge and pneumatization of the maxillary sinus often limit the volume of bone available for implant placement on maxillary posterior teeth. Most clinicians suffer difficulties from poor bone quality and quantity on maxillary posterior site. Thus, the success of maxillary posterior implant surgery depends on the increase of the available bone and obtaining a good initial stability of the implant after maxillary sinus reconstruction. The maxillary sinus augmentation methods include a crestal approach and a lateral approach. Less morbidity and complications after operation is major advantage to sinus augmentation using crestal approach than lateral approach. However, when the residual ridge height is ${\geq}6mm$, it is known that crestal approach is appropriate. Also delayed implantation after sinus augmentation is recommended in severely atrophic ridge. We present the three cases of implant placement simultaneously sinus augmentation using crestal approach in posterior maxilla site with ${\leq}3mm$ of residual alveolar bone.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.4
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• pp.371-392
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• 2011

The purpose of this study was to comparatively analyze the stress distribution according to the inclinations of abutments and angulations of the implant fixtures under occlusal loading force. Three study models with straight and $15^{\circ}$ and $25^{\circ}$-angled abutments were prepared following the insertion of Implants parallel to the long axis of the tooth. Additional two experimental models were fabricated with $15^{\circ}$ and $25^{\circ}$ fixture inclinations. Using ANSYS 11, a finite element analysis program, the magnitudes of stress distribution were analyzed. The magnitude of stress under loading was lowest when the load was applied vertically onto the axis of implant. And the magnitude of stress under compound(vertical+oblique) loading was increased as the inclination of implant abutment and fixture was increase. But, the distribution of stress was different as the loading conditions, because of the horizontal offset. As the offset between the axis of loading and the central axis of the implant increased, the stress was increased.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.3
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• pp.323-337
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• 2010

The objective of this study was to examine the availability of the new impression coping by comparing with conventional coping in implant pick-up impression technique. Five implant fixtures were installed on #14, 21, 23, 25, 27 in acrylic resin model. That model with 5 fixtures was standard model, which was divided 3 groups; using new flag type impression coping, conventional impression coping splinted with self-curing resin, conventional impression coping without splinting. We made metal circular cones for calculation 3-dimensional coordinates by attaching to implant fixtures or analogs. Three-dimensional relationships of each model were calculated. Data was analyzed by multiple ANOVA and Bonferroni. The accuracy of impression between using new flag type impression coping and conventional impression coping did not show differences in 3 - dimensional analysis.Within limitations of this study, the new flag type impression coping is available in implant pick-up impression technique.