Fracture resistance of a second generation of zirconia implants after artificial ageing: An in vitro study.

OBJECTIVES

The aim of this study was to determine the bending moments of a further developed generation of a one-piece zirconia implant system, which, for example, has a reduced diameter in the neck area compared to the predecessor model.

METHODS

A total of 48 one-piece ceramic implants with diameters of 3.6 mm and 4.1 mm were included. After preparation of the abutments of 50 % of the implants, 32 out of the 48 implants were subjected to artificial ageing in a chewing simulator (Force: 98 N; 1.2 or 5 million loading cycles; thermocyclicing: 5 °C / 55 °C). The implants were then subjected to static loading until fracture in order to determine the maximum load forces to calculate the bending moments.

RESULTS

Implants tested after 1.2 million loading cycles exhibited the highest bending moments (3.6 mm diameter without abutment preparation: 496.1 ± 50.6 Ncm; 3.6 mm diameter with abutment preparation: 507.9 ± 53.5 Ncm; 4.1 mm diameter without abutment preparation: 612.5 ± 49.0 Ncm; 4.1 mm diameter with abutment preparation: 656.9 ± 26.8 Ncm). In contrast, unloaded implants showed the lowest values (3.6 mm diameter without abutment preparation: 443.0 ± 38.6 Ncm; 3.6 mm diameter with abutment preparation: 436.1 ± 42.8 Ncm; 4.1 mm diameter without abutment preparation: 570.3 ± 64.8 Ncm; 4.1 mm diameter with abutment preparation: 560.9 ± 51.5 Ncm), while implants subjected to 5 million cycles of loading showed bending moment values between these two groups.

CONCLUSIONS

Within the limits of the present study, preparation of the abutment did not appear to have a negative effect on stability. Also, artificial ageing did not seem to have a negative effect on the fracture resistance; a possible negative effect on the bending moment would have to be investigated with >5 million loading cycles. The measured maximum fracture loads were generally higher than the masticatory forces described in the literature.

CLINICAL SIGNIFICANCE: The investigated zirconia implants seem to be a viable alternative to titanium implants.