MATERIAL AND METHODS

A 18mm diameter rod of Ti–6Al–4V alloy ELI grade according to the standard ASTMF136-02 supplied by SURGIVAL was cut into 2 mm thick disk specimens, ground through successive grades of SiC paper to 1200 grade, degreased with a conventional detergent and rinsed in tap water followed by deionised water. The specimens were then chemically polished (CP).

The disks were anodized only on one side by using a two electrode cell in a suitable electrolyte. TiO₂ barrier layers, without fluoride (BL), were produced by anodizing in 1 M H₂SO₄ at 15 mA cm-2 to 90 V, reaching 200 nm of thickness.

Fluoride barrier layers (FBL) were produced in an electrolyte containing 1 M NH₄H₂PO₄ and 0.15 M NH₄F, at constant voltage controlled at 20 V for 120 min at 20°C; the thickness of the layer is 140 nm.

Laboratory biofilm-forming strains of Staphylococcus aureus 15981 [6] and Staphylococcus epidermidis ATCC 35984 were used in adherence studies, which were performed using the protocol by Kinnari et al [7]. Photographs obtained were studied by ImageJ software. Statistical analysis was performed by EPI-INFO software. The experiments were performed in triplicates