Introduction: Micro-organism adhesion and plaque formation is affected by surface free energy (SFE), surface roughness, hydrophilicity, surface chemistry, surface charge and the presence of proteins.
Aims: The aim of this study was to assess and compare surface characteristics of surgical grade cobalt chromium alloy (CCM) and of commercially pure titanium (cpTi).
Method: Nine metallic cylinders were machined to precise standards from each material. Surface roughness was measured at four different points on each sample and the average Ra value was calculated for each material. Contact angles were obtained using the sessile-drop method and applied in calculating the SFE. Surface hardness was evaluated by means of a Vickers hardness micro-indentation.
Results: Surface roughness was similar for both metals, but total SFE values and Vickers surface hardness scores showed significant differences (p < 0.0001).
Conclusion: SFE analysis showed CCM to be more hydrophobic and that oral bacteria might therefore be less adherent than to cpTi. The mean Vickers Hardness scores of the cpTi were significantly lower (p < 0.0001), suggesting that CCM may be more resistant to surface modifications and surface roughening, thus remaining smoother with less plaque accumulation than cpTi. This study demonstrated that CCM might be a suitable alternative implant abutment material.