• Journal of the Korean Academy of Esthetic Dentistry
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• v.21 no.1
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• pp.51-60
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• 2012

• 대한치과보철학회:학술대회논문집
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• 1999.04a
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• pp.88.1-88.1
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• 1999

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.1
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• pp.1-14
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• 1996

Abutment screw loosening of dental implant is a major problem in the treatment of dental implant. The purpose of this study was to examine the effect on the prevention of screw loosening according to tightening method and using of washer. In the first experiment, using a implant fixture and precisely fabricated temporary cylinder, the loosening torque was measured by tightening the screw 5 times repeatedly. In the second experiment, the fabricated crown and implant fixture was tightened by the screw that is attatched washer and then the loosening torque was measured after loading it 1800, 12600 times under the force of 150N. The results were as follows. 1. The highest loosening torque appeared after tightening 3 times repeatedly(p<0.01). 2. When the washer was used, the loosening torque was increased significantly under the loading 1800 times(p<0.01), 3. When the washer was used, the loosening torque was increaed under the loading 12600 times, but it is statistically not significant(p<0.01). The first experiment results mean that 3 times repeated tightening screw is most effective clinically. The second results mean that washer is effective in prevention screw loosening, but the effect is decreased with increasing load.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.1
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• pp.67-73
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• 2012

Fixed dental prostheses such as inlay, onlay, crown, and bridge fabricated by CAD/CAM technique combined with digital impressions is getting popular due to the recent rapid progress of digital impression taking system. For the scope of implant prosthesis, however, digital intra-oral scan hasn't been actively utilized for the fabrication of superstructures. In this case report, 6 cases of titanium-milled custom abutment based on the iTero intra-oral scan data were introduced, five of them were restored with screw-type prosthesis after cementation (SCRP) and the clinical results were satisfactory on restoring the function and esthetics.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.2
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• pp.154-160
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• 2018

When making conventional removable partial denture for the remaining teeth where the remaining teeth are only on one side, rotation of the denture occurs -in function- on the axis of the connected remaining teeth. If the edentulous portion is long, it becomes harder to obtain retention and stability for the abutment as the importance of the mucous membrane support is elevated. Such movements of denture decrease denture retention and stability, put excessive stress on the abutment, and give bad influence on periodontal health. Therefore, additional implant placement can be of a good choice in gaining additional retention and stability for partial denture. Thus hereby we report this clinical case as successful results were obtained by placing implants symmetrical to the remaining teeth and putting implant-supported surveyed crowns on the implants, allowing the partial denture to be designed to accept varying components and to have suitable path of insertion.

• Journal of Periodontal and Implant Science
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• v.45 no.1
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• pp.23-29
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• 2015

Purpose: This study was conducted to compare the cumulative survival rates (CSRs) and the incidence of postloading complications (PLCs) between a bone-level internal connection system (ICS-BL) and an external connection system (ECS). Methods: The medical records of patients treated with either a ICS-BL or ECS between 2007 and 2010 at Asan Medical Center were reviewed. PLCs were divided into two categories: biological and technical. Biological complications included >4 mm of probing pocket depth, thread exposure in radiographs, and soft tissue complications, whereas technical complications included chipping of the veneering material, fracture of the implant, fracture of the crown, loosening or fracture of the abutment or screw, loss of retention, and loss of access hole filling material. CSRs were determined by a life-table analysis and compared using the log-rank chi-square test. The incidence of PLC was compared with the Pearson chi-squared test. Results: A total of 2,651 implants in 1,074 patients (1,167 ICS-BLs in 551 patients and 1,484 ECSs in 523 patients) were analyzed. The average observation periods were 3.4 years for the ICS-BLs and 3.1 years for the ECSs. The six-year CSR of all implants was 96.1% (94.9% for the ICS-BLs and 97.1% for the ECSs, P=0.619). Soft tissue complications were more frequent with the ECSs (P=0.005) and loosening or fracture of the abutment or screw occurred more frequently with the ICS-BLs (P<0.001). Conclusions: Within the limitations of this study, the ICS-BL was more prone to technical complications while the ECS was more vulnerable to biological complications.

• Journal of Technologic Dentistry
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• v.46 no.2
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• pp.21-27
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• 2024

Purpose: This study aimed to analyze the stress distribution and deformation in implant abutments made from titanium (Ti-6Al-4V), zirconia, and polyetheretherketone (PEEK), including their screws and fixtures, under various loading conditions using finite element analysis (FEA). Methods: Three-dimensional models of the mandible with implant abutments were created using Siemens NX software (NX10.0.0.24, Siemens). FEA was conducted using Abaqus to simulate occlusal loads and assess stress distribution and deformation. Material properties such as Young's modulus and Poisson's ratio were assigned to each component based on literature and experimental data. Results: The FEA results revealed distinct stress distribution patterns among the materials. Titanium alloy abutments exhibited the highest stress resistance and the most uniform stress distribution, making them highly suitable for long-term stability. Zirconia abutments showed strong mechanical properties with higher stress concentration, indicating potential vulnerability to fracture despite their aesthetic advantages. PEEK abutments demonstrated the least stress resistance and higher deformation compared to other abutment materials, but offered superior shock absorption, though they posed a higher risk of mechanical failure under high load conditions. Conclusion: The study emphasizes the importance of selecting appropriate materials for dental implants. Titanium offers durability and uniform stress distribution, making it highly suitable for long-term stability. Zirconia provides aesthetic benefits but has a higher risk of fracture compared to titanium. PEEK excels in shock absorption but has a higher risk of mechanical failure compared to both titanium and zirconia. These insights can guide improved implant designs and material choices for various clinical needs.

• The Journal of Advanced Prosthodontics
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• v.3 no.2
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• pp.85-89
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• 2011

PURPOSE. The purpose of this study was to evaluate the amount of resorption and thickness of labial bone in anterior maxillary implant using cone beam computed tomography with Hitachi CB Mercuray (Hitachi, Medico, Tokyo, Japan). MATERIALS AND METHODS. Twenty-one patients with 26 implants were followed-up and checked with CBCT. 21 OSSEOTITE $NT^{(R)}$. (3i/implant Innovations, Florida, USA) and 5 $OSSEOTITE^{(R)}$. implants (3i/implant Innovations, Florida, USA) were placed at anterior region and they were positioned vertically at the same level of bony scallop of adjacent teeth. Whenever there was no lesion or labial bone was intact, immediate placement was tried as possible as it could be. Generated bone regeneration was done in the patients with the deficiency of hard tissue using $Bio-Oss^{(R)}$. (Geistlich, Wolhusen, Switzerland) and $Bio-Gide^{(R)}$. (Geistlich, Wolhusen, Switzerland). Second surgery was done in 6 months after implant placement and provisionalization was done for 3 months. Definite abutment was made of titanium abutment with porcelain, gold and zirconia, and was attached after provisionalization. Two-dimensional slices were created to produce sagittal, coronal, axial and 3D by using OnDemand3D (Cybermed, Seoul, Korea). RESULTS. The mean value of bone resorption (distance from top of implant to labial bone) was $1.32 \;{\pm}\; 0.86\; mm$ and the mean thickness of labial bone was $1.91 \;{\pm}\; 0.45 \;mm$. CONCLUSION. It is suggested that the thickness more than 1.91 mm could reduce the amount and incidence of resorption of labial bone in maxillary anterior implant.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.905-917
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• 2022

This study was conducted to evaluate the use of the MAR function and the image quality of the image when examining with each radiation dose. A simple Periapical phantom was made to set up an implant, and images were obtained and analyzed according to the presence or absence of MAR function for each radiation dose using CBCT equipment. In this study, MEAN, SNR, and CNR values were obtained using the Image J program, and through statistical analysis, images were the most quantitative and suitable values when the Abutment of Implant was 100 kVp and 8 mA, and when the Center of Implant and Apex of Implant were 100 kVp and 9 mA. As a result, it was confirmed that if the radiation dose increased, the Pixel Value, SNR, and CNR values of the image rose up so that the quality of the image improved, and using the MAR function reduced artifacts.

• Corrosion Science and Technology
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• v.10 no.6
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• pp.212-217
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• 2011

In this study, corrosion characteristics of TiN and ZrN film on the abutment screw by arc-ion plating were investigated using a potentiodynamic anodic polarization test in deaerated 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. The surface morphologies of the coating layers before and after corrosion test were investigated by a field-emission scanning electron microscope (FE-SEM) and a energy dispersive x-ray spectroscopy (EDS). The surfaces of the TiN and ZrN coated abutment screws showed the smooth surfaces without mechanical defects like scratches which can be formed during the manufacturing process, compared with those of the non-coated abutment screw. The corrosion and passive current densities of TiN and ZrN coated abutment screws were lower than those of the non-coated abutment screw.