In-vitro performance of different anterior zirconia or/and titanium implant/abutment systems

Method: Seven implant-abutment combinations were restored with identical full-zirconia crowns (n=8 per system, tooth 11). For simulating clinical anterior loading situations, the implants were fixed under 135° to the tooth axis. The following combinations were investigated:

Thermal cycling and mechanical loading (TC: 2x3000 cycles between 5°C/55°C, dist. water, ML: 50N for 1.2x10⁶ cycles; f=1.6Hz; mouth opening: 2mm) with standardized antagonists was performed to simulate five years of oral service.  During TCML all restorations were permanently controlled for failures. Restorations which failed during TCML were investigated in detail with scanning electron microscopy (SEM Quanta, Phillips). After TCML all restorations, which survived were loaded to fracture (No. 1446, Zwick, v= 1mm/min). Mean and standard deviation of fracture forces were calculated and statistically analysed (one-way ANOVA; α=0.05).

Result: Independently from material combinations screwed systems showed partly loosening of screws during simulation. Zirconia one-piece implants/abutments provided no failures during TCML. For the bonded systems only one abutment lost retention. Fracture values varied from 187.4 N (zirconia-bonded-zirconia) to 524.3N (zirconia one part). Control titanium-screwed-titanium system showed a fracture resistance of 394.1N. Statistical differences were found between the individual systems.

Conclusion: On basis of the actual in-vitro data it can be assumed that different material combinations for implants and abutments as well as different assembly systems can provide good in-vitro performance and fracture resistance, which may be satisfactory for an anterior clinical application.