The implant-abutment interface of alumina and zirconia abutments

Background: Although ceramic and titanium abutments are widely used in clinical practice, the mechanical characterization of the implant-abutment interface for ceramic abutments has not been evaluated after the dynamic loading. Purpose: The purpose of this study was to assess the implant-abutment interface after the dynamic loading of titanium, alumina, and zirconia abutments. Materials and methods: Fifteen aluminum oxide, zirconium oxide, and titanium abutments were manufactured by the Procera System (R) (Nobel Biocare AB, Goteborg, Sweden) and were connected to empty set 3.75 x 13-mm regular platform implants (MK III, Nobel Biocare AB) secured in a 30 degrees inclined plane. A mechanical testing machine applied compressive dynamic loading between 20 and 200 N at 1 Hz on a standard contact area of copings cemented on abutments for 47.250 cycles. The measurements of microgaps at the implant-abutment interface from the labial, palatinal, mesial, and distal surfaces of each specimen were undertaken by scanning electron microscope analyses prior to and after the experiments. The data of the microgaps before and after the dynamic loading were statistically assessed using the Wilcoxon signed rank test and the Kruskal-Wallis variance analysis (alpha = 0.05). Results: Coping fracture, abutment fracture, or abutment screw loosening or fracture was not detected in any specimen during the entire test period. After the dynamic loading, the titanium abutment control group revealed an increased microgap (3.47 mu m) than zirconia (1.45 mu m) and alumina (1.82 mu m) groups at the palatinal site (p < .05). The mean measurement values at different measurement sites of specimens within and between each abutment group were similar (p > .05). Conclusions: Owing to their comparable microgap values at the implant-abutment interface after the dynamic loading, ceramic abutments can withstand functional forces like conventional titanium abutments.