study of the friction coefficient between metallic and ceramic materials for dental implants: fretting phenomenon investigation

Tooth loss is a common issue that can bring the patient to lose the regular aesthetics of the month as the correct chewing mechanics. Nowadays the dental implants represent a valid replacement of natural teeth. The most common design for them involves three different units, the crown usually made in Zirconia that thanks to its superior mechanical properties and aesthetics permit to bear the chewing loads and provides a natural appearance, the abutment, across the gingiva, usually made in Titanium for is good biocompatibility and the root in direct contact with the bone also made in Titanium. Despite of that these two materials have still some problems mostly related to the the wear by their coupling. In the latest years the dental implants productors focused their attentions always more on a particular form of wear: the fretting. The phenomenon of fretting occurs every time that small amplitude flows between your surfaces in contact occur for a large number of cycles. This movement leads to two forms of damage: superficial wear and fatigue deterioration. The aim of this study was to evaluate the tribological behavior of 3 different type of titanium against zirconia to show what of them as the best behaviour under fretting conditions. Pins made in CpTi, Ti-6Al-4V and DLC (Ti-6Al-4V ) were tested against zirconia balls to reproduce the fixture-abutment contact of a dental implant. The fretting phonomenon was simulated with a Biotribometer (MicroForce, Ducom). For Evaluating the different behaviours of the materials they were tested with 2 protocols of diffent Normal load 0.5 and 2 N. Both the tests were runned for 40-minutes with the frequency of 1 Hz with 3 different steps with a dynamic change of stroke lenght: 5 min with 0.02mm, 5 min with 0.05 mm, 30 min with 0.1 mm. For every Pin was evaluated the geometric scar wear by means of an optical microscope and the change of roughness with a light profilometer (profilm 3D Filmetrics). The tests were made under the lubrication of the BioXtra gel solution.