• The Journal of Korean Academy of Prosthodontics
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• v.42 no.5
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• pp.583-596
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• 2004

Statement of problem : Stress concentration on the neck bone affects the bone resorption, and finally the implant survival. Purpose: In order to examine the stress distribution on the neck bone and prosthesis abutment for implants, decreasing abutment sizes were used. Material and methods : Axisymmetric models were used to obtain the data required. These models were composed of 4mm implants with 3.4mm and 4mm abutments, 5mm implants with 3.4mm and 5mm abutments and 6mm implants with 3.4mm and 6mm abutments. All abutments were designed to received a 10mm high by 10mm diameter gold crown. Functional element analysis was used to obtain these results using data that consisted of 50 N vertical and 45 degree inclination forces. Results : 1. Changing the diameter of the abutment on the implant affects the effect of the inclination forces more than the effect of the vortical forces. 2. Changing the diameter of the abutment on the implant affect the effect of the inclination forces more than the effect of the vertical forces. 3. Experimentation showed that the larger diameter implants provided a decreased neck bone stress, whereas a larger diameter abutment provided a decrease marginal abutment stress. 4. Experimentation showed that the neck bone and abutment received more stress from inclination forces than vertical forces, Conclusions: By decreasing the size of the abutment on the implant we were able to diminishneck bone stress.

• Journal of Technologic Dentistry
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• v.32 no.4
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• pp.317-325
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• 2010

Purpose: The aim of this study is to make some basic materials to find retention force difference based on the total height of CAD/CAM zirconia abutment used for implant, retention force difference based on how to regulate the height of the abutment, retention force difference based on the size and retention force difference based on the design group. Methods: The retention force was measured by being pulled at the speed of 1mm/min after being combined with zirconia block and abutment using Temp-BOND of Kerr. The experiment was done at the research lab of OSTEM in Busan by useing UNIVERSAL TESTING MACHINE on March 3rd, 2010. Results: After analysing the total height and the retention force, p-value had minor difference by 0.01 statistically. Namely, 3mm, 4mm, 5mm had the retention force difference and we could see retention force difference on 3mm and 5mm at the post test. After analyzing how to regulate the height and retention force, p-value had minor difference by 0.000 statistically. Namely, 1mm and 2mm had the retention difference and we could see that 1mm and 2mm with the total height had retention difference. After analyzing the retention force based on the size, p-value had minor retention force difference by 0.000 statistically. Namely, 7 different size had retention force difference and we could see the size 21.9mm, 32.9mm, 32.9mm, 38.4mm, 48.9mm and 54.9mm had retention force difference. Conclusion: Namely 9 different design group had retention difference and we could see that 9 design group with 5.6.7.8 design group and 9 design group with 1.2.3.4. design group had retention force.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.3 no.1
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• pp.44-50
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• 1995

Abutment dies which resemble the actual size and shape of crown abutment is essential in most of the research area of fixed prosthodontics like marginal accuracy, crown seating, behavior of luting agent and so on. Seeing the large portion of research is done with round shaped dies in different size and cone angles, the necessity of research on the crown abutment is self-evident. 500 molar abutments were collected randomly through the commercial dental laboratoy, regrdless of their position in the dental arch, sex, and age. The measurements of 22 points of a die were done, and the results were as fogbows : 1. The height of the molar dies was $3.9{\pm}1.2mm$ 2. The bucco-lingual width was $8.9{\pm}1.2mm$ at the base, and $7.4{\pm}1.2mm$ at the occlusal. 3. The desio-sistal width was $8.2{\pm}1.2mm$ at the base, and $7.0{\pm}1.3mm$ at the occlusal.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.5
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• pp.662-670
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• 2005

Statement of problem: Little is known about the effect of abutment preparation procedure on do-torque values in different implant platform and the relationship of final do-torque values with different implant platform size. Purpose: This study evaluated the effect of abutment preparation procedure on do-torque values in different implant platform and the relationship of final do-torque values with different implant platform size. Material and method: Six ITI implants (2 narrow-neck implants, 2 regular-neck implants, 2 wide-neck implants) and six Branemark implants (2 narrow platforms, 2 regular platforms, 2 wide platforms) were embedded in each acrylic resin block with epoxy resin. Eighteen $synOcta^(R)$ abutments (6 narrow-neck implant-abutments, 6 regular-neck implant-abutments, 6 wide-neck implant-abutments) and eighteen esthetic abutments (6 narrow platform-abutments, 6 regular platform-abutments, 6 wide platform-abutments) were tightened to each implant with digital torque gauge. Initial do-torque values were measured using digital torque gauge. After preparation of abutments, Final do-torque values were measured with digital torque gauge. Results and conclusion: 1. Screws loosening or abutments motion were not detected in all experimental group, but some scratches of implant-abutment joints were detected in all group 2. Reduction ratios of final do-torque values were greater than initial do-torque values in all measured group, except in narrow-neck implant-abutment group (p<0.05). 3. Reduction ratios of final do-torque values in wide-neck implant-abutment group were greater than regular-neck implant-abutment group (p<0.01). 4. The greatest standard deviation value was detected in wide platform group in both implant systems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.15-20
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• 2019

This paper evaluated the construction costs of 11 design cases to decrease the horizontal forces applied to the abutment. They include two abutment types, which are to improve backfill materials for a reversed T-shaped abutment and geosynthetic Reinforced Abutment for Railways (RAR). The first type of economic analysis was that the internal friction angles of backfill materials were increased from Φ=35° to Φ=40° and 50° for a reversed T-shaped abutment. In addition, the second type was the cases with the design of geosynthetic RAR. When friction angles of 40° or 50° were applied through the improvement of the backfill material, the decrease in construction cost of the abutment was not large (2.0~3.9%), even though the horizontal forces applied to the abutment had decreased to 18~48%. In the case of applying the RAR, however, a maximum 30% cost reduction was evaluated by the decrease in horizontal force to "0" theoretically. The cost reduction resulted from the decrease in wall thickness, base slab size, and number and material change of pile foundation for the abutment.

• Structural Engineering and Mechanics
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• v.34 no.5
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• pp.635-662
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• 2010

In this study, the effect of superstructure-abutment continuity on the distribution of live load effects among the girders of integral abutment bridges (IABs) is investigated. For this purpose, two and three dimensional finite element models of several single-span, symmetrical integral abutment and simply supported (jointed) bridges (SSBs) are built and analyzed. In the analyses, the effect of various superstructure properties such as span length, number of design lanes, girder size and spacing as well as slab thickness are considered. The results from the analyses of two and three dimensional finite element models are then used to calculate the live load distribution factors (LLDFs) for the girders of IABs and SSBs as a function of the above mentioned parameters. LLDFs for the girders are also calculated using the AASHTO formulae developed for SSBs. Comparison of the analyses results revealed that the superstructure-abutment continuity in IABs produces a better distribution of live load effects among the girders compared to SSBs. The continuity effects become more predominant for short span IABs. Furthermore, AASHTO live load distribution formulae developed for SSBs lead to conservative estimates of live load girder moments and shears for short-span IABs.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.3
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• pp.375-382
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• 1999

The purpose of this article is to present the clinical and laboratory procedures for single tooth restoration using 'Combination Implant Crown'. It is cemented on implant abutment and that abutment is screw-retained over implant body. This type of implant restorations has the advantages of cement-retained restoration while being antirotational and retrievable. And, more esthetic and functional result can be achieved by minimizing the size of access hole. The results were as follows : 1. Preparation of abutment below the cuff line should be avoided 2. Axial reduction of implant abutment should not be excessive because it may weaken the abutment 3. More esthetical and functional occlusal surface was achieved with a minimal access hole which is slightly larger than the diameter of hex driver to enable future total retrievability. 4. Combination Implant Crown has the advantages of both the cement-retained and screw-retained type implant restoration. 5. Cementation between implant crown and abutment reduces screw loosening through even force distribution

• Structural Engineering and Mechanics
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• v.10 no.6
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• pp.621-633
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• 2000

Dynamic responses of a bridge system with several simple spans under longitudinal seismic excitations are examined. The bridge system is modeled as the multiple oscillators and each oscillator consists of four degrees-of-freedom system to implement the poundings between the adjacent oscillators and the friction at movable supports. Pounding effects are considered by introducing the impact elements and a bi-linear model is adopted for the friction force. From the parametric studies, the pounding is found to induce complicated seismic responses and to restrain significantly the relative displacements between the adjacent units. The smaller gap size also restricts more strictly the relative displacement. It is found that the relative displacements between the abutment and adjacent pier unit became much larger than the responses between the inner pier units. Consequently, the unseating failure could take a place between the abutment and nearby pier units. It is also found that the relative displacements of an abutment unit to the adjacent pier unit are governed by the pounding at the opposite side abutment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.508-517
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• 2018

This study evaluated the construction costs of 11 design cases to decrease the horizontal forces applied to an abutment. They include two kinds of abutment types, which are used to improve the backfill materials for reversed T-shaped abutment and geosynthehtic reinforced abutment for railways (RAR). In the first economic analysis, the internal friction angles of the backfill materials were increased from ${\Phi}=35^{\circ}$ to ${\Phi}=40^{\circ}$ and $50^{\circ}$ for a reversed T-shaped abutment. The second analysis examined cases with the design of a geosynthehtic RAR. When the friction angles were $40^{\circ}$ or $50^{\circ}$ after improvement of the backfill material, the reduction in the construction cost of the abutment was not as large (2.0-3.9%), even though the horizontal forces on the abutment were decreased by 18-48%. However, in the case of applying the RAR, a maximum cost reduction of 30% was achieved by decreasing the horizontal force to zero. The cost reduction results from the decreased wall thickness, base slab size, and the number of pile foundations for the abutment, as well as changing the material.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.5
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• pp.617-625
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• 2003

Statement of problem : There are many studies focused on the effect of shape of futures on stress distribution in the mandibular bone. However, there are no studies focused on the effect of the abutment types on stress distribution in mandibular bone. Purpose : The purpose of this study is to investigate the effect of three different abutment types on the stress distributions in the mandibular bone due to various loads by performing finite element analysis. Material and method : Three different implant systems produced by Warantec (Seoul, Korea), were modeled to study the effect of abutment types on the stress distribution in the mandibular bone. The three implant systems are classified into oneplant (Oneplant, OP-TH-S11.5). internal implant (Inplant, IO-S11.5) and external implant (Hexplant, EH-S11.5). All abutments were made of titanium grade ELI. and all fixtures were made of titanium grade IV. The mandibular bone used in this study is constituted of compact and spongeous bone assumed to be homogeneous, isotropic and linearly elastic. A comparative study of stress distributions in the mandibular bone with three different types of abutment was conducted. Results : It was found that the types of abutments have significant influence on the stress distribution in the mandibular bone. It was due to difference in the load transfer mechanism and the size of contact area between abutment and fixture. Also the maximum effective stress in the mandibular bone was increased with the increase of inclination angle of load. Conclusion : It was concluded that the maximum effective stress in the bone by the internal implant was the lowest among the maximum effective stresses by other two types.