Mechanical testing of thin-walled zirconia abutments

Although the use of zirconia abutments for implant-supported restorations has gainedmomentum with the increasing demand for esthetics, little informed design rationalehas been developed to characterize their fatigue behavior under different clinical scenarios.However, to prevent the zirconia from fracturing, the use of a titanium connection in bicomponent aesthetic abutments has been suggested. Objective: Mechanical testing ofcustomized thin-walled titanium-zirconia abutments at the connection with the implantwas performed in order to characterize the fatigue behavior and the failure modes forstraight and angled abutments. Material and Methods: Twenty custom-made bi-componentabutments were tested according to ISO 14801:2007 either at a straight or a 25° angle conditions at 20°C±5°C. Mean values and standard deviations were calculated for eachgroup. All comparisons were performed by t-tests assuming unequal variances. The level ! " #light and then in a scanning electron microscope. Results: Straight and angled abutmentsmean maximum load was 296.7 N and 1,145 N, the dynamic loading mean Fmax was 237.4$ %& ' $( ) $ ! * *# * * % + + / ! * ; * application, whereas in the straight abutments, fractures were located coronally and closeto the thinly designed areas at the cervical region. Conclusion: Angled or straight thinwalled zirconia abutments presented similar Fmax under fatigue testing despite the differentbending moments required for fracture. The main implication is that although zirconiaangled or straight abutments presented similar mechanical behavior, the failure modetended to be more catastrophic in straight (fracture at the cervical region) compared toangled abutments.