Fatigue fracture of implant system using TiN and WC coated abutment screw

Abstract

Dental implant systems are subject to failure in the screw connection part which can occur due to screw loosening or fracture. For solving the problem of loosening, some researchers had carried out the TiN(titanium nitride) and WC(tungsten carbide) coating on the abutment screw, while fatigue failure may still be not researched as an issue of coating materials. In this study, fatigue test was performed to estimate the fatigue fracture of coated abutment screw for implant system according to the ISO 14801. For this purpose, TiN and WC film coating was carried out on the abutment screw using EB-PVD and sputtering, respectively. For the fatigue test, the implant fixture and abutment were tightened to a torque 32Ncm using digital torque gauge with 0.1Ncm accuracy. Each prepared samples were fixed to uniaxial sinusoidal cyclic loading machine (ADT-AV01k1, Shimadzu, Japan) under load control between 42-420N and 58-580N. Fractured surface was observed with FE-SEM and EDS. The fatigue life of implant system used TiN and WC coated abutment screw was found to be relatively longer compared to non-coated abutment screw at 420N. Also, fatigue life of TiN coated sample showed longer than that of other samples at 580N. After the fatigue test at 420N, fatigue striations were showed on the fractured surface of non-coated abutment screw. The semi-cleavage surface was mainly observed on the TiN coated surface. Fatigue striations were regularly appeared at crack propagation step with striation thickness of 0.5 μm/cycle. © 2011 Published by Elsevier Ltd.