Surface, microstructural and mechanical characterization of contemporary implant abutment screws

The aim of the present work was to evaluate six commercially available abutment screws by characterising roughness parameters, microstructure and mechanical properties.

Six abutment screws from each implant system, were used. The surface roughness parameters (S_a, S_q, S_sk, S_ku, S_pk, S_k and S_vk) were identified by an optical interferometric profiler. Microstructural observations and crystallographic analysis were performed using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectroscopy (EDX) device for elemental analysis and an X-ray diffractometer (XRD), respectively. The Martens Hardness (HM), Indentation Modulus (E_IT), elastic index (η_IT) and Vickers hardness (HV) of all specimens were determined by instrumented indentation testing (IIT). The results were analyzed by one-way ANOVA and Tukey multiple-comparison tests (a=0.05).

EDX and XRD showed the abutment screws to be mixed α- and β-phase titanium alloys. Microstructural analysis revealed a fine homogeneous microstructure without porosity, consisting of fine dispersoid rods of β-phase embedded in a continuous α-phase matrix. Statistically significant differences were found among the mechanical properies and surface roughness parameters apart from S_q, S_pk and S_vk.

The tested abutment screws showed significant differences in the probed properties, and, thus, differences in their clinical behaviour are anticipated.