PURPOSE. The aim of this study was to evaluate the interface accuracy of computer-assisted designed and manufactured (CAD/CAM) titanium abutments and implant fixture compared to gold-cast UCLA abutments. MATERIALS AND METHODS. An external connection implant system (Mark III, n=10) and an internal co...
PURPOSE. The aim of this study was to evaluate the interface accuracy of computer-assisted designed and manufactured (CAD/CAM) titanium abutments and implant fixture compared to gold-cast UCLA abutments. MATERIALS AND METHODS. An external connection implant system (Mark III, n=10) and an internal connection implant system (Replace Select, n=10) were used, 5 of each group were connected to milled titanium abutment and the rest were connected to the gold-cast UCLA abutments. The implant fixture and abutment were tightened to torque of 35 Ncm using a digital torque gauge, and initial detorque values were measured 10 minutes after tightening. To mimic the mastication, a cyclic loading was applied at 14 Hz for one million cycles, with the stress amplitude range being within 0 N to 100 N. After the cyclic loading, detorque values were measured again. The fixture-abutment gaps were measured under a microscope and recorded with an accuracy of ${\pm}0.1{\mu}m$ at 50 points. RESULTS. Initial detorque values of milled abutment were significantly higher than those of cast abutment (P.05). After cyclic loading, detorque values of cast abutment increased, but those of milled abutment decreased (P<.05). There was no significant difference of gap dimension between the milled abutment group and the cast abutment group after cyclic loading. CONCLUSION. In conclusion, CAD/CAM milled titanium abutment can be fabricated with sufficient accuracy to permit screw joint stability between abutment and fixture comparable to that of the traditional gold cast UCLA abutment.
PURPOSE. The aim of this study was to evaluate the interface accuracy of computer-assisted designed and manufactured (CAD/CAM) titanium abutments and implant fixture compared to gold-cast UCLA abutments. MATERIALS AND METHODS. An external connection implant system (Mark III, n=10) and an internal connection implant system (Replace Select, n=10) were used, 5 of each group were connected to milled titanium abutment and the rest were connected to the gold-cast UCLA abutments. The implant fixture and abutment were tightened to torque of 35 Ncm using a digital torque gauge, and initial detorque values were measured 10 minutes after tightening. To mimic the mastication, a cyclic loading was applied at 14 Hz for one million cycles, with the stress amplitude range being within 0 N to 100 N. After the cyclic loading, detorque values were measured again. The fixture-abutment gaps were measured under a microscope and recorded with an accuracy of ${\pm}0.1{\mu}m$ at 50 points. RESULTS. Initial detorque values of milled abutment were significantly higher than those of cast abutment (P.05). After cyclic loading, detorque values of cast abutment increased, but those of milled abutment decreased (P<.05). There was no significant difference of gap dimension between the milled abutment group and the cast abutment group after cyclic loading. CONCLUSION. In conclusion, CAD/CAM milled titanium abutment can be fabricated with sufficient accuracy to permit screw joint stability between abutment and fixture comparable to that of the traditional gold cast UCLA abutment.
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문제 정의
The aim of this study was to assess the screw joint stability of CAD/CAM titanium and conventional gold-cast UCLA abutment with both external and internal connections. This was achieved by means of measuring the detorque values and the gaps between fixture and abutment after cyclic loading.
제안 방법
A poor fit with resultant lack of frictional resistance to rotation may be a possible cause of screw loosening.25For this reason, the comparative studies between the premachined UCLA abutment and the CAD/CAM milled titanium abutment were performed by measuring detorque values and gap dimensions.
The occlusal force is distributed in a complex manner in vector and magnitude in vivo. For this study, the load was applied on a single implant crown with an already determined magnitude and vector for a limited time. The actual preload achieved in the components is dependent on the friction between components, finish of the interfacial surface, and material properties.
In this study, the fifty gap measurements around the outer perimeter of the fixture-abutment connection for each specimen were performed with a microscope. The minimum of 50 measurements necessary for determining gap sizes is based on a report by Groten.
The UCLA abutment used in this study is the premachined abutments made of gold alloy, which can be cast directly onto to allow integration of the restoration with the abutment. It has the advantages of overcoming angulation and esthetic problem, but it may reflect difficulties with distortions introduced by the casting technique, and/ or porcelain firing cycles or limitations inherent in the finishing procedures.
Two implant designs from the same manufacturer were selected in this study to represent both the external and internal designs in the screw joint stability. The Brånemark Mark III implant was used for the design of the external connection, and hexagonal feature for rotational resistance, indexing, and lateral stabilization.
대상 데이터
Brånemark Mark III implant system (Nobel biocare, USA) as a representative of the external connection system (n=10), and Replace Select implant system (Nobel biocare, USA) which has the characteristic triangular internal connection structure (n=10) were selected for this study.
Finally, the remaining titanium around abutment top was cut out. The other 10 fixtures were connected to the UCLA abutment (Nobel biocare, USA) which was carved after wax add-up, burned out, and casted to the gold structure. One individual completed all waxing and castings for consistency.
성능/효과
The results of these experiments demonstrate that CAD/CAM titanium abutments can be fabricated with sufficient accuracy to permit screw joint stability between abutment and fixture comparable to that of the traditional gold cast UCLA abutment. These findings may have important implications, since the price for fabrication can be reduced once the process becomes organized.
후속연구
For this study, we focused solely on abutment and connection design, and did not consider those factors mentioned above. In addition to the earlier limitations, investigations involving more realistic loading conditions and larger sample sizes are necessary for future research.
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