In vitro performance of zirconia and titanium implant/abutment systems for anterior application

Objectives: To investigate the type of failure and fracture resistance behaviour of different zirconia and titanium implant/abutment systems for anterior application. Methods: Eight groups of implant-abutment combinations (n = 8/system) were restored with identical full-contour zirconia crowns. The systems represented one-piece and multi-piece zirconia (Z) or titanium (T) implants/abutments with different types of connection (screwed = 5, bonded = B). The following combinations (implant-abutment-connection) were investigated: ZZS, ZZB, ZZZB (three-piece), ZTS, TTS, TTS reference, and Z (one-piece, 2x). To simulate clinical anterior loading situations the specimens were mounted into the chewing simulator at an angle of 135 degrees and subjected to thermal cycling (2 x 3000 x 5 degrees/ 55 degrees C) and mechanical loading (1.2 x 10(6) x 50 N; 1.6 Hz). Fracture resistance and maximum bending stress were determined for all specimens that survived ageing. Data were statistically analyzed with the Kolmogorov-Smimov-test and one-way ANOVA (alpha = 0.05). Survival performance was calculated with the Kaplan-Meier Log-Rank test. Results: Independent of the material combinations screwed systems showed partly failures of the screws during simulation (ZZS: 3x, ZTS: 8x, TTS: 3x). Screw failures were combined with implant/abutment fractures of zirconia systems. Zirconia one-piece implants and the reference system did not show any failures, and only one specimen of the systems with a bonded connection (ZZZB) fractured. Mean (+/- standard deviation) fracture forces and maximum bending stresses differed significantly (p = 0.000) between 187.4 +/- 42.0 N/ 250.0 +/- 56.0 N/mm(2) (ZZZB) and 524.3 +/- 43.1 N/753.0 +/- 61.0 N/mm(2) (Z). Conclusions: Both material (zirconia or titanium) and the type of connection influenced failure resistance during fatigue testing, fracture force, and maximum bending stress. Clinical significance: Different material combinations for implants and abutments as well as different types of connection achieved acceptable or even good failure and fracture resistance that may be satisfactory for anterior clinical application. (C) 2014 Elsevier Ltd. All rights reserved.