• The Journal of Korean Academy of Prosthodontics
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• v.39 no.6
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• pp.625-632
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• 2001

Statement of Problem. Objective and quantitative measurement of implant stability is very important from implant installation to long-lasting maintenance period thereafter. Purpose of study. This study was to evaluate and compare two ISQ and PTVs on the implant stability measurements according to the increased effective implant length. Materials and methods. Twenty self-tapping fixtures were installed in the bovine scapula and in 10 of those for group I, ISQ and PTVs were obtained in the vertical/horizontal directions according to the increased effective implant length using $Osstell^{TM}$ and $Periotest^{(R)}$. After stability measurement, removal torques were measured between the after installation and after thread exposure group. Results. ISQ and PTVs showed decreased and increased values according to the increased abutment length. Apart from PTVs, ISQ values were shown higher in horizontal direction to the long axis of bone in both the after installation and the after thread exposure groups. Removal torque values were shown higher in after installation group. Conclusion. From the results of this study, implant stability measurement using resonance frequency analysis was more sensitive and discriminative than PTVs measurement.

• The korean journal of orthodontics
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• v.41 no.5
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• pp.354-360
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• 2011

Objective: To investigate the effects of different pilot-drilling methods on the biomechanical stability of self-tapping mini-implant systems at the time of placement in and removal from artificial bone blocks. Methods: Two types of artificial bone blocks (2-mm and 4-mm, 102-pounds per cubic foot [102-PCF] polyurethane foam layered over 100-mm, 40-PCF polyurethane foam) were custom-fabricated. Eight mini-implants were placed using the conventional motor-driven pilot-drilling method and another 8 mini-implants were placed using a novel manual pilot-drilling method (using a manual drill) within each of the 2-mm and 4-mm layered blocks. The maximum torque values at insertion and removal of the mini-implants were measured, and the total energy was calculated. The data were statistically analyzed using linear regression analysis. Results: The maximum insertion torque was similar regardless of block thickness or pilot-drilling method. Regardless of the pilot-drilling method, the maximum removal torque for the 4-mm block was statistically higher than that for the 2-mm block. For a given block, the total energy at both insertion and removal of the mini-implant for the manual pilot-drilling method were statistically higher than those for the motor-driven pilot-drilling method. Further, the total energies at removal for the 2-mm block was higher than that for the 4-mm block, but the energies at insertion were not influenced by the type of bone blocks. Conclusions: During the insertion and removal of mini-implants in artificial bone blocks, the effect of the manual pilot-drilling method on energy usage was similar to that of the conventional, motor-driven pilot-drilling method.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.3
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• pp.379-392
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• 2005

Statement of problem. One of the common problems of dental implant prosthesis is the loosening of the screw that connects each component, and this problem is more common in single implant-supported prostheses with external connection, and in molars. Purpose. The purposes of this study were: (1) to compare the initial abutment screw detorque values of the six different implant-abutment interface designs, (2) to compare the detorque values of the six different implant-abutment interface designs after cyclic loading, (3) to compare the detorque values of regular and wide diameter implants and (4) to compare the initial detorque values with the detorque values after cyclic loading. Material and methods. Six different implant-abutment connection systems were used. The cement retained abutment and titanium screw of each system were assembled and tightened to 32Ncm with digital torque gauge. After 10 minutes, initial detorque values were measured. The custom titanium crown were cemented temporarily and a cyclic sine curve load(20 to 320N, 14Hz) was applied. The detorque values were measured after cyclic loading of one million times by loading machine. One-way ANOVA test, scheffe’s test and Mann-Whitney U test were used. Results. The results were as follows : 1. The initial detorque values of six different implant-abutment connections were not significantly different(p>0.05). 2. The detorque values after one million dynamic cyclic loading were significantly different (p<0.05). 3. The SS-II regular and wide implant both recorded the higher detorque values than other groups after cyclic loading(p<0.05). 4. Of the wide implants, the initial detorque values of Avana Self Tapping Implant, MIS and Tapered Screw Vent, and the detorque values of MIS implant after cyclic loading were higher than their regular counterparts(p<0.05). 5. After cyclic loading, SS-II regular and wide implants showed higher detorque values than before(p<0.05).

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.2
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• pp.192-209
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• 2004

Purpose : The purpose of this study was to evaluate the machining accuracy and consistency of implant/abutment/screw combination or internal connection type. Material and methods: In this study, each two randomly selected internal implant fixtures from ITI, 3i, Avana, Bicon, Friadent, Astra, and Paragon system were used. Each abutment was connected to the implant with 32Ncm torque value using a digital torque controller or tapping. All samples were cross-sectioned with grinder-polisher unit (Omnilap 2000 SBT Inc) after embeded in liquid unsaturated polyester (Epovia, Cray Valley Inc). Then optical microscopic and scanning electron microscopic(SEM) evaluations of the implant-abutment interfaces were conducted to assess quality of fit between the mating components. Results : 1) Generally, the geometry of the internal connection system provided for a precision fit of the implant/abutment into interface. 2) The most precision fit of the implant/abutment interface was provided in the case of Bicon System which has not screw. 3) The fit of the implant/abutment interface was usually good in the case of ITI, 3I and Avana system and the amount of fit of the implant/abutment interface was similar to each other. 4) The fit of the implant/abutment interface was usually good in the case of Friadent, Astra and Paragon system. The case of Astra system with the inclined contacting surface had the most Intimate contact among them. 5) Amount of intimate contact in the abutment screw thread to the mating fixture was larger in assembly with two-piece type which is separated screw from abutment such as Friadent, Astra and Paragon system than in that with one-piece type which is not seperated screw from abutment such as ITI, 3I and Avana system. 6) Amount of contact in the screw and the screw seat of abutment was larger in assembly of Friadent system than in asembly of Astra system of Paragon system. Conclusion: Although a little variation in machining accuracy and consistency was noted in the samples, important features of all internal connection systems were the deep, internal implant-abutment connections which provides intimate contact with the implant walls to resist micro-movement, resulting in a strong stable interface. From the results of this study, further research of the stress distribution according to the design of internal connection system will be required.

• The korean journal of orthodontics
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• v.41 no.1
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• pp.25-35
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• 2011

Objective: The purpose of this study was to optimize the thread pattern of orthodontic microimplants. Methods: In search of an optimal thread for orthodontic microimplants, an objective function stability quotient (SQ) was built and solved which will help increase the stability and torsional strength of microimplants while reducing the bone damage during insertion. Selecting the AbsoAnchor SH1312-7 microimplant (Dentos Inc., Daegu, Korea) as a control, and using the thread height (h) and pitch (p) as design parameters, new thread designs with optimal combination of hand p combination were developed. Design soundness of the new threads were examined through insertion strain analyses using 3D finite element simulation, torque test, and clinical test. Results: Solving the function SQ, four new models with optimized thread designs were developed (h200p6, h225p7, h250p8, and h275p8). Finite element analysis has shown that these new designs may cause less bone damage during insertion. The torsional strength of two models h200p6 and h225p7 were significantly higher than the control. On the other hand, clinical test of models h200p6 and h250p8 had similar success rates when compared to the control. Conclusion: Overall, the new thread designs exhibited better performance than the control which indicated that the optimization methodology may be a useful tool when designing orthodontic microimplant threads.