• The Journal of Korean Academy of Prosthodontics
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• v.59 no.4
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• pp.497-507
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• 2021

All-on-six concept can be used as one of the treatment options to maximize the use of available residual alveolar bone for implant-supported fixed prosthesis on edentulous patients. But this process is complex and cumbersome. Digital system can be used at multiple steps, from implantation to prosthetic restoration, to overcome this shortcoming. In this case of a maxillary edentulous patient aged 76, digital system was used for restoration of 1-piece design, screw retained fixed prosthesis from diagnosis, implant surgery to fabrication of provisional and final prosthesis. For preoperative diagnosis and treatment planning stage, intra-oral information of a patient was digitalized by direct intra-oral scan. Surgical guide and immediate provisional prosthesis was designed based on this digitalized data. Patient's inconvenience was minimized by applying immediate provisional prosthesis, which was delicately fabricated according to the location data of six implants on most suitable residual alveolar bone. Then, final prosthesis was designed and fabricated going through new interim prosthesis which was newly designed and fabricated, considering patient's requests, stable vertical dimension and occlusion, and esthetic factors using digital system. We hereby report a case successfully applying digital system to multiple steps including implant surgery to fabricating prosthesis, to simplify existing complicated implant treatment procedure to an edentulous patient.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.70-81
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• 2009

Statement of problem: The position and length of cantilever influence on the stress distribution of implants, superstructure and bone. In edentulous mandible, implant-supported cantilever prostheses that based 4 or 6 implants between mental foramens has been attempted. Excessive bite force loaded at cantilever prosthesis causes bone resorption and breakage of superstructure prosthesis around posterior implants. To complement the cantilever length of conventional prosthesis, In 1992, (McCartney) introduced "cantilever-rest-implant" and Malo reported "All-on-Four" in 2003. Purpose: Analyze and compare the stress distribution of conventional cantilever prostheses with rest implant and All-on-$Four^{TM}$ implant prostheses. Material and method: The external loads(300 N vertically, 75 N horizontally) are applied to first molar area. The stress value, stress distribution and aspect of stress dispersion are analyzed by three-dimensional finite element analysis program, ANSYS ver. 10.0. Results: 1. The rest implant and "All-on-Four" implant system are superior to conventional cantilever prostheses to reduce stress on the bone and the superstructure around implants. 2. The rest implant was of the greatest advantage to stress distribution on bone, implant and superstructure. 3. With same number of implants, distally tilted implants are preferred to conventional cantilever prostheses for reducing the length of cantilever.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.5 no.4
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• pp.216-223
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• 2012

When the implants are inserted, the recovery period of bone matrix is around 8 to 12 weeks. The osseointegration plays an important role in recovery period of bone matrix around the implants. In this study, we surveys how mechanical stimuli, ultrasonic stimuli, laser stimuli, LED stimuli affects the osseointegration. We found that $1.47^{\sim}1.6MHz$ stimuli are ideal for all stimuli.

• 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.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.312-320
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• 2019

One of the fastest growing segments of implant dentistry is the utilization of computed tomography (CT) scan data and treatment planning software in conjunction with guided surgery for implant reconstruction cases. Computer assisted planning systems and associated surgical templates have established a predictable, esthetic, functional technique for placing and restoring implants. Especially, a philosophy of restoratively driven implant placement has been generally adopted. Recently, a variety of commercial dental fields have released their scanning and fabricating protocols and methods for restorations. This process is still being investigated and developed for the most precise and predictable outcome. This case report describes a female patient who wanted dental implants in fully edentulous areas. Restoratively driven implant placements were performed with surgical guide and the patient was fully satisfied with the clinical results, and at 5-year post restorative follow-up assessment, both implant and prosthesis were proved clinical success.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.1
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• pp.81-85
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• 2015

This report describes the prosthetic treatment of a patient with multiple missing teeth. Installation of five fixtures on maxilla with sinus lift and six fixtures on mandible with ramal bone graft were performed. With implant supported all-ceramic with zirconia core using CAD/CAM technology and porcelain-fused-to-gold prosthesis, treatment with positive outcome which satisfies both functional and esthetical aspect was obtained.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.2
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• pp.164-172
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• 2021

Purpose: The purpose of this study was to analyze the level of interest that common Internet users have in dental implant using a Google Trends, and to compare the level of interest with big data from National Health Insurance Service. Materials and methods: Google Trends provides a relative search volume for search keywords, which is the average data that visualizes the frequency of searches for those keywords over a specific period of time. Implant was selected as the search keyword to evaluate changes in time flows of general Internet users' interest from 2015 to 2019 with trend line and 6 month moving average. Relative search volume for implant was analyzed with the number of patients who received National Health Insurance coverage for implant. Interest in implant and conventional denture was compared and popular related search keywords were analyzed. Results: Relative search volume for implant has increased gradually and showed a significant positive correlation with the total number of patients (P<.01). Interest in implant was higher than denture for most of the time. Keywords related to implant cost were most frequently observed in all years and related search on implant procedure was increasing. Conclusion: Within the limitations of this study, the public interest in dental implant was gradually increasing and specific areas of interest were changing. Web-based Google Trends data was also compared with traditional data and significant correlation was confirmed.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.316-323
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• 2011

Purpose: The purpose of this study was to investigate the effect of different thread designs on the marginal bone stresses around dental implant. Materials and methods: Standard ITI implant(ITI Dental Implant System; Straumann AG, Waldenburg, Switzerland), 4.1 mm in diameter and 10 mm in length, was selected as control. Test implants of four different thread patterns were created based on control implant, i.e. maintaining all geometrical design of control implant except thread pattern. Four thread designs used in test implants include (1) small V-shape screw (model A), (2) large V-shape screw (model B), (3) buttress screw (model C), and (4) trapezoid screw (model D). Surface area for unit length of implant was 14.4 $mm^2$ (control), 21.7 (small V-shape screw), 20.6 (large V-shape screw), 17.0 (buttress screw) and 28.7 $mm^2$ (trapezoid screw). Finite element models of implant/bone complex were created using an axisymmetric scheme with the use of NISA II/DISPLAY III (Engineering Mechanics Research Corporation, Troy, MI, USA). A load of 100 N applied to the central node on the crown top either in parallel direction or at 30 degree to the implant axis (in order to apply non-axial load to the implant NKTP type 34 element was employed). Quantification and comparison of the peak stress in the marginal bone of each implant model was made using a series of regression analyses based on the stress data calculated at the 5 reference points which were set at 0.2, 0.4, 0.6, 0.8 and 1.0 mm from implant wall on the marginal bone surface. Results: Results showed that although severe stress concentration on the marginal bone cannot be avoided a substantial reduction in the peak stress is achievable using different thread design. The peak marginal bone stresses under vertical loading condition were 7.84, 6.45, 5.96, 6.85, 5.39 MPa for control and model A, B, C and D, respectively. And 29.18, 26.45, 25.12, 27.37, 23.58 MPa when subject to inclined loading. Conclusion: It was concluded that the thread design is an important influential factor to the marginal bone stresses.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.4
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• pp.387-392
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• 2016

Purpose: The aim of this study was to investigate the effects of grooved abutments on abutment screw loosening. Materials and methods: This study was conducted to evaluate the abutment screw loosening after 6 months for 50 patients (51 implants) treated at the department of Prosthodontics in Yonsei University Dental Hospital from March, 2015 to July, 2015. A control group with non-grooved abutment consists of 30 implants, and an experimental group with grooved abutment consists of 21 implants. Astra, Straumann, Implantium, Osstem system were used in the study. The abutments with loose screws cases after a period of 6 months has been investigated, with two kinds of measurements: 1) measuring the additional rotational angle on abutment during placement with the same force, 2) measuring the PTV on bucco-cervical area of implant crown. All data collected has been analyzed by normality test followed by Mann-Whitney test using SPSS program. Results: No complications were reported after 6 months for the 51 implants. Abutment screw loose and crown fracture have not been seen in the study groups. The data collected from the two measurements showed no significant differences between the two groups with P-value 0.576 (average= control group: $7.35^{\circ}$, experimental group: $4.75^{\circ}$) for the additional rotational angle measurement and with P-value 0.767 for PTV. Conclusion: There are no significant differences between the grooved and non-grooved abutment in screw stability. However, further studies with long-term followups and larger group of patients is needed in order to investigate the effects of grooved abutment on screw stability.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.3
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• pp.212-217
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• 2018

Purpose: This study was to assess clinically the incidence of abutment screw loosening of posterior implant-supported fixed prosthesis and its affecting factors. Materials and methods: 391 implant-supported crowns restored from January 2013 to January 2016 were included in this study. All restorations were fabricated with either a single crowns or a splinted crown, and cemented with temporary cement. The incidence of abutment screw loosening is investigated and gender, restoration position, opposing teeth, restoration type, abutment connection type were assessed as possible factors affecting abutment screw loosening. Results: During the observation period (2 - 5 years), abutment screw loosening was found in 29 restorations (7.4%). It took 3 to 48 months (means 19.5 months) to loose the screw, and three of these implants were fractured. Among the factors considered, there were statistically significant differences at abutment screw loosening rate between molar group (9.4%) and premolar group (2.6%) (P<.019). According to the type of opposing teeth, there were statistically significant differences between nature teeth (74.7%) and implant (25.0%), removable denture (3%) (P<.019). The other possible factors did not have a significant effect on loosening of the abutment. Conclusion: The incidence of abutment screw loosening in posterior restoration was 7.4%. Abutment screw loosening were more likely to occur in molars group than premolar group, and according to the opposing teeth, there were the greatest frequency in nature teeth than implant and removal denture. There was a statistically significant difference.