Bacterial Adhesion to Grade 4 and Grade 5 Turned and Mildly Acid-Etched Titanium Implant Surfaces: An In Vitro and Ex Vivo Study

Aim of the present study was to investigate the bacterial adhesion to titanium (Ti) implant surfaces, different for composition and topographic features. Grade 4 and 5 turned (T-4, T-5,) and mildly acid-etched (MA-4, MA-5) Ti 6 × 1 mm disks were topographically analyzed by scanning electronic microscopy and 3D profilometry. Bacterial cultures (Streptococcus sanguinis) were in vitro seeded and, after two and six hours, adherent bacteria were quantified by colony-forming unit (CFU) counting. Ti samples were also exposed to the oral environment of six periodontally healthy volunteers and, after 12 h, the formed biofilm was evaluated by CFU counting. Inter-group differences were tested by the Mann–Whitney U-Test (α = 0.05). MA surfaces were significantly rougher than T ones, whereas no difference between grade 4 and grade 5 disks was detected. Significantly higher in vitro bacterial adhesion for MA than T disks was shown at two and six hours. Significantly higher values of CFU counting for MA than T surfaces and for grade 5 than grade 4 disks were found at the 12 h-ex vivo test. Bacterial adhesion showed to be sensitive to both Ti surface topography and composition, with possible implications on peri-implant tissue health maintenance.