Mechanical properties and shock absorption of dental implants equipped with abutments made of composite matherials

The modern dental endosseous implants include some parts which can be mounted at successive time steps of the tooth replacement. Due to their different requirements - mechanical, aesthetic or related to the comfort -the parts can be profitably constituted by different materials, homogeneous or composite. A crucial component is the abutment connecting the "artificial root" integrated into the bone to the artificial tooth: it is subjected high to axial and transversal loads and preferably it must be clear or semi-transparent because the artificial tooth is not completely opaque. Some composite materials have been tested and compared with the classic components made of titanium alloy. Preliminary in vivo long term analysis on the bone surrounding the implants show that the bone re-absorption rate decreases for the implants equipped with some composite abutments. In order to better understand the implants behavior, the pieces have been tested by means of quasi static and dynamic bending tests and fatigue tests; the damping level of the implant system have been tested by means of vibration and impact tests. The test equipment includes an artificial tooth to be impacted and an implant frame, both instrumented with accelerometers. The results highlight that the impact peaks transmitted from the tooth to the bone vary with the abutment material. These findings together with the information on fatigue strength of the pieces can drive the design of new endossoeus implants. A numerical model of the implant for dynamic simulation, which take into account the distribution and the direction of the fibers of each layer of the composite material, allows to optimize the system mechanical properties. The next step of the research will be the in vivo and mechanical test of the optimized abutments.