Changes in the abutment-implant interface in Morse taper implant connections after mechanical cycling: a pilot study.

PURPOSE: The aim of this study was to measure and compare, using scanning electron microscopy, the abutment-implant interface of a Morse taper system before and after cyclic loading. MATERIALS AND METHODS: Four Morse cone implants and four solid abutments were used. These abutments had been machined to reduce the diameter of the part corresponding to the site of prosthesis cementation. They were then screwed onto the implants and torqued to 25 N. Under a scanning electron microscope, 32 images (16 before and 16 after cycling) of the interfaces were obtained under x1,000 and x5,000 magnification. The samples were subjected to 345,600 cycles with a fatigue testing machine, in which the applied load was 80 N and the frequency was 4 Hz, to simulate chewing. With appropriate software (Image Tool 3.0), the marginal gaps of the interfaces before and after load cycling were measured. The data were analyzed with the Student t test at a significance level of 5%. RESULTS: Significant differences were found between interfaces before and after cycling. Prior to mechanical cycling, the Morse taper implant/abutment assemblies exhibited an average gap size of 3.34 +/- 2.17 mum, whereas the average gap size after mechanical cycling was 1.35 +/- 0.64 mum. CONCLUSION: After mechanical cycling, there was a significant decrease in the size of the gap, which indicated better adaptation and sealing ability at the level of the microgap.