Removal torque of taper and indexed abutment: mechanical loading effect

Objectives: The long term success of an implant supported restoration and the health of the surrounding tissues is closely related to prosthetic components accuracy and its fit to the fixture and abutment/implants interface stability as well as its strength when subjected to masticatory loads. The aim of this study was to examine the effect of cyclic fatigue on the reversal torque values of dental implant/abutments joints. Methods: Twenty implants with either internal morse taper or indexed (hexagonal internal positioning interface) configuration (Conexão Sistemas de Prótese – Brazil) were used to test two kinds of implant/abutment interface: morse taper and indexed. The assemblies were divided into 2 test groups (n=10): G1: implant and solid morse taper abutment; G2: implant and indexed abutment. All abutments were torque tightened into the implant to 20 N/cm with the aid of a digital torque device, and subjected to 500.000 fatigue cycles. Torque removal testing was then performed on the assemblies. Intergroup comparisons were made with Mann-Whitney tests at 95% confidence level. Results: The results showed that G1 (12,01±3,53 N/cm) was statistically different from G2 (3,05±1,62 N/cm) (p-value = 0,0002< 0,05). Conclusion: This study showed that the morse taper abutment provided superior torque removal values after fatigue than the indexed abutment.