Techniques comparison detachment biofilm formed on titanium

Objectives: The accumulation of the oral biofilmaround dental implants can induce inflammatory reactions. Such reactions may occurin soft tissue(mucositis), or bone tissue (periimplantitis). The study of biofilm formation on titanium surfaces is fundamental for the understanding of the different stages of biofilm formation in this particular surface. The objective of this study is to compare two methods of disruption of microbial biofilms on titanium surfaces: mechanical action and chemical-mechanical action,represented here by the addition of proteinase K to the original mechanical protocol.
Methods: Cylindrical samples of titanium were prepared (Ti6Al4V) (15 mm x 8mm x 5mm), using a precision cutting machine (Isomet) and polished. Streptococcus mutans ATCC 25175 was grown on BHI agar plates, under microaerophilic conditions, for 48 hours at 37°C. Bacterial cells were centrifuged at 5,000 rpm 10 min at 4^oCand resuspended in TSB medium supplemented with urea (1g /L), yeast extract (2 g /L) and sucrose (200 g /L),to obtain a suspension with an optical density (OD₆₃₀) of 0.6, corresponding to 1x10⁸ CFU/mL, where titanium samples were immersed for 48h. Samples were subsequently washed twice with PBS, and biofilms were disrupted by either (D1) vortexing for 1 min in 1 ml of PBS, or (D2)vortexingfor 1 min in the presence of1% proteinase K (Sigma-Aldrich).The obtained bacterial suspensionswere diluted in PBS,plated on BHI agar plates and incubated at 37°C for 48 hours to determine the number of viable colony forming units (CFU). All experiments were performed in triplicate.
Results: Results showed that the average number of bacteria detached fromthe biofilm formed over the titanium samples was greater for the chemical-mechanical treatment (D2 = 6.1x10²CFU/mL) than for the mechanical treatment (D1 = 2.0x10²CFU/mL). This difference wasstatistically significant, asdetermined by One-Way analysis of McNemar test (p < 0.05).
Conclusions: Conclusion: the addition of 1% proteinase K in the buffer used for vortexing the samples increased the efficiency of S. mutansbiofilm disruption from the titanium surface.