A comparative study of the 1-piece and 2-piece conical abutment joint: the strength and the fatigue resistance

Kwon, Taek Ka; Yang, Jae Ho; Kim, Sung Hun; Han, Jung Suk; Lee, Jai Bong

Abstract

STATEMENT OF PROBLEM: The performance and maintenance of implant-supported prostheses are primarily dependent upon load transmission both at the bone-to-implant interface and within the implant-abutment-prosthesis complex. The design of the interface between components has been shown to have a profound influence on the stability of screw joints. PURPOSE. The Purpose of this study was to compare the strength and the fatigue resistance of 1-piece and 2-piece abutment connected to oral implant, utilizing an internal conical interface. MATERIAL AND METHODS: Twenty Implatium(R) tapered implants were embedded to the top of the fixture in acrylic resin blocks. Ten Combi(R)(1-piece) and Dual(R)(2-piece) abutments of the same dimension were assembled to the implants, respectively. The assembled units were mounted in a testing machine. A load was applied perpendicular to the long axis of the assemblies and the loading points was at the distance of 7mm from the block surface. Half of 1-piece and 2-piece abutment-implant units were tested for the evaluation of the bending strength, and the others were cyclically loaded for the evaluation of the fatigue resistance until plastic deformation occurred. Nonparametric statistical analysis was performed for the results.
RESULTS
Mean plastic and maximum bending moment were 1,900+/-18Nmm, 3,609+/-106Nmm for the 1-piece abutment, and 1,250+/-31Nmm, 2,688+/-166Nmm for the 2-piece abutment, respectively. Mean cycles and standard deviation when implant-abutment joint showed a first plastic deformation were 238,610+/-44,891. cycles for the 1-piece abutment and 9,476+/-3,541 cycles for the 2-piece abutment. A 1-piece abutment showed significantly higher value than a 2-piece abutment in the first plastic bending moment (P<.05), maximum bending moment (P<.05) and fatigue strength (P<.05).
CONCLUSION
Both 1-piece and 2-piece conical abutment had high strength and fatigue resistance and this suggests long-term durability without mechanical complication. However, the 1-piece conical abutment was more stable than the 2-piece conical abutment in the strength and the fatique resistance.