The effect of titanium implant surface modification on the dynamic process of initial microbial adhesion and biofilm formation

Purpose: The aim of the study was to investigate the dynamic process of biofilm adhesion on titanium implant with two surface treatments, either pickled (PT) or moderately roughened by sandblasting with large grits and acid-etched (SLA). Materials and methods: Two types of titanium disks with various surface treatments, i.e. PT and SLA with respective surface roughness (Sa) of 0.3 μm and 1.4 μm, were used as substrata. Three types of biofilms, Streptococcus mutans, Streptococcus sanguinis and polymicrobial biofilms (Microcosm), were grown on the two respective types of titanium disks for 2 h, 1 day, and 7 days. The formation of the biofilms was quantified by colony forming unit (CFU) count, and the structure of the biofilms on the titanium disks was observed by scanning electron microscope (SEM). Results: At 2 h, the number of bacterial cells adhered to SLA surfaces was significantly higher than those to PT surfaces for all tested microorganisms. On day 1 and 7, no differences in biofilm CFU counts were observed between SLA and PT surfaces for S. mutans and Microcosm biofilms, while the S. sanguinis biofilm formation on SLA surfaces was significantly higher than the biofilm on PT surfaces throughout the whole test period. SEM images showed the increasing biofilm formation in time for all types of biofilms. Microcosm biofilms displayed different morphology from the other two single-species biofilms. Conclusions: The higher roughness of a titanium surface would favor the early bacterial adhesion of S. mutans, S. sanguinis and Microcosm. However, as the biofilm became mature, the influence of surface roughness was diminished in a bacterial species dependent manner. Our results underline the importance of dynamic biofilm form