In vitro assessment of three types of zirconia implant abutments under static load

Statement of problem Although various zirconia abutments have been introduced, insufficient data exist regarding the maximum load capacity of internal tri-channel connection zirconia implant abutments with various implant-abutment interfaces. Purpose The purpose of this in vitro study was to compare the maximum load capacity of 3 different types of internal tri-channel connection zirconia abutments and to assess their mode of failure. Material and methods The study investigated 3 groups (n=20) of zirconia implant abutments with different implant-abutment interfaces. Group AllZr consisted entirely of zirconia (Aadva CAD/CAM Zirconia Abutment), group FrZr of a titanium insert friction-fitted to the zirconia abutment component (NobelProcera Abutment Zirconia), and group BondZr of a titanium insert bonded to the zirconia abutment component (Lava Zirconia abutment). All the abutments were thermal cycled for 20 000 cycles between 5°C and 55°C. Sixty test implants made of titanium (Dummy NobelReplace) were embedded in autopolymerizing acrylic resin, and 60 zirconia copings (Lava Zirconia) with a uniform thickness of 2.0 mm were fabricated and bonded to the abutments. A universal testing machine was used to statically load all the specimens at a crosshead speed of 1 mm/min. The maximum load was recorded and used as the failure load. The fractured specimens were collected and representative specimens were studied with a stereomicroscope and scanning electron microscope (SEM). One-way ANOVA and post hoc comparisons with the Tukey HSD tests were used for statistical analysis (α=.05). Results The mean (SD) maximum load capacity was 484.6 (56.6) N for NobelProcera, 503.9 (46.3) N for Aadva, and 729.2 (35.9) N for Lava abutments. The maximum load capacity of Lava abutments was significantly higher than that of Aadva or NobelProcera (P< 05). No significant difference between Aadva and NobelProcera abutments was noted. The mode of failure among the Aadva, NobelProcera, and Lava abutments was different. Conclusions With standard diameter internal tri-channel connection implants, the maximum load capacity of the Lava abutment was significantly higher than that of the Aadva or NobelProcera abutment. No significant difference in maximum load capacity was noted between Aadva and NobelProcera abutments. However, the fracture behavior of all 3 abutments was different.