지대주의 반복적인 착탈에 따른 임플랜트 고정체의 external hexagon과 지대주 internal hexagon의 변화에 관한 연구
Surface change of external hexagon of implant fixture and internal hexagon of abutment after repeated delivery and removal of abutment
정석원, 김희중, 정재헌,
소속 상세정보
정석원 ( Jung Seok-Won ) - 조선대학교 치과대학 치과보철학교실
김희중 ( Kim Hee-Jung ) - 조선대학교 치과대학 치과보철학교실
정재헌 ( Chung Chae-Heon ) - 조선대학교 치과대학 치과보철학교실
KMID : 0362420050430040528
Abstract
Statement of problem: Repeated delivery and removal of abutment cause some changes such as wear, scratch or defect of hexagonal structure. It may increase the value of rotational freedom(RF) between hexagonal structures.
Purpose: The purpose of this study was to evaluate surface changes and rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment after repeated delivery and removal under SEM and toolmaker’s microscope.
Materials & Methods: Implant systems used for this study were 3i and Avana. Seven pairs of implant fixture, abutment and abutment screws for each system were selected and all fixtures were perpendicularly mounted in liquid unsaturated polyesther with dental surveyor. Each one was embedded beneath the platform of fixture. Surfaces of hexagonal structure before repeated closing and opening of abutment were observed using SEM and rotational freedom was measured by using toolmaker’s microscope. Each abutment was secured to the implant fixture by each abutment screw with recommended torque value using a digital torque controller and was repeatedly delivered and removed by 20 times respectively. After experiment, evaluation for the change of hexagonal structures and measurement of rotational freedom were performed.
Results: The results were as follows ; 1. Wear of contact area between implant fixture and abutment was considerable in both 3i and Avana system. Scratches and defects were frequently observed at the line-angle of hexagonal structures of implant fixture and abutment. 2. In the SEM view of the external hexagon of implant fixture, the point-angle areas at the corner edge of hexagon were severely worn out in both systems. It was more notable in the case of 3i systems than in that of Avana systems. 3. In the SEM view of the internal hexagon of abutment, Gingi-Hue abutment of 3i systems showed severe wear in micro-stop contacts that were machined into the corners to prevent rotation and cemented abutment of Avana systems showed wear in both surface area adjacent to the corner mating with external hexagon of implant fixture. 4. The mean values of rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment were 0.48+/-0.04 degrees in pre-tested 3i systems and 1.18+/-0.25 degrees after test, and 1.80+/-0.04 degrees in pre-tested Avana systems and 2.61+/-0.16 degrees after test. 5. Changes of rotational freedom after test showed statistically a significant increase in both 3i and Avana systems(p<0.05, paired t-test). 6. Statistically, there was no significant difference between amount of increase in the rotational freedom of 3i systems and amount of increase in that of Avana ones(p>0.05, unpaired t-test).
Conclusion: Conclusively, it was considered that repeated delivery and remove of abutment by 20 times would not have influence on screw joint stability. However, it caused statistically the significant change of rotational freedom in tested systems. Therefore, it is suggested that repeated delivery and remove of abutment should be minimal as possible as it could be and be done carefully. Additionally, it is suggested that the means or treatment to prevent the wear of mating components should be devised.
키워드
Wear;abutment;fixture;Hexagonal structure;Rotational freedom(RF);Screw joint stability
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