Particle-abrasion of Titanium Abutments Increases Retention for Zirconia Crowns

Objectives: The study objective was to compare the effect of air-borne particle abrasion (APA) and fatigue to retention forces of zirconia crowns cemented with two different heights of titanium abutments.
Methods: Thirty titanium implant abutment bases (Variobase RC, Straumann) 3.5mm (n=15) and 5.5mm (n=15) in height and thirty Y-TZP zirconia crowns were used. The 3.5mm-height titanium bases were allocated to Groups A to D. Group A: (n=10) no surface treatment, Group B: (n=5) surface treatment with APA, Group C: (n=5), fatigue test without surface treatment, and Group D (n=5), fatigue test with APA treatment. Identical group allocation was applied to the 5.5mm-height titanium bases in Groups E to H. All crowns and titanium abutments of the surface-roughening groups were performed APA (50μm, alumina), bonded with a dual-cure resin cement (Panavia V5, Kuraray America), light cured (20s), and applied force (2N, 15min) followed by storing under moist condition (37°C, 24h). The specimens for groups B, D, G and H were tested by cyclic loading of 100,000 cycles in a wet environment under a peak load of 1,800 N. A 'pull-out' test was performed for each specimen using a universal testing machine (Instron 5566A) until complete separation. Maximum tensile loads were recorded for retention forces between crown and abutment. Data were analyzed with ANOVA and Tukey HSD (a=0.05).
Results: Failure pattern was predominantly adhesive. The APA groups recorded significantly higher retention. The 5.5mm-height titanium base showed greater retention than 3.5mm-height, solely in the APA groups. Group H: 5.5mm-height, APA and the fatigue test marked significantly higher retention than the static test group.
Conclusions: The APA treatment on titanium abutments increased the retention with zirconia crowns. The titanium base height had significant influence on retention forces with APA treatment. Except for the group B the fatigue test did not decrease retention forces.