Evaluation of castable and premachined metal base abutment/implant interfaces before and after cyclical load.

PURPOSE: The purpose of this study was to compare the vertical fit of the castable abutment/implant and premachined base metal abutment/implant interface, before and after cyclic loading. MATERIALS AND METHODS: Ten UCLA abutments were distributed in 2 groups: castable and premachined with a cobalt-chromium metal base. The abutments were cast in cobalt-chromium alloy and were screwed onto implants (3.75 x 13 mm, external hexagon) with a 32 N.cm torque. The vertical gap (in micrometers) at the interface abutment/implant was evaluated by linear microscope 2 times: after torque and after cyclic load (1 million cycles, 400 N). RESULTS: The mean values of the vertical gap at the castable abutment/implant and premachined abutment/implant interfaces before and after cyclic load were 5.33 to 6.64 microm and 7.36 to 8.16 microm, respectively. The mean values of the vertical gap were statistically analyzed (ANOVA and t test, P </= 0.05). Vertical gap values of the castable abutment/implant interface were not significantly different from those of the premachined abutment/implant interface, before (P = 0.154) and after (P = 0.471) cyclical loading. CONCLUSION: Castable and premachined base metal abutments showed similar gaps at the implant/abutment interface, both after applying torque and after cyclic loading.