In vitro evaluation of a multispecies oral biofilm on different implant surfaces

Biofilm accumulation on implant surfaces is one of the most important factors for early and late implant failure. Because of the related clinical implications, the aim of this in vitro study was to compare the bacterial cell attachment of a four-species oral biofilm on titanium discs of purity grade 2 and 4, with machined surfaces and etched-thermochemically modified with Avantblast (R). The in vitro biofilm model was composed of early (Actinomyces naeslundii, Streptococcus gordonii), secondary (Veillonella parvula), and intermediate (Fusobacterium nucleatum ssp. polymorphum) colonizers of tooth surfaces. A total of 36 discs were divided into four groups: Tigr2-c (titanium grade 2, machined surface), Tigr2-t (titanium grade 2, modified surface with Avantblast (R)), Tigr4-c (titanium grade 4, machined surface), Tigr4-t (titanium grade 4, modified surface with Avantblast (R)). The experiment was repeated three times. Biofilm viability was tested with 1% 2, 3, 5-triphenyltetrazolium chloride solution and bacterial cell quantification by checkerboard DNA-DNA hybridization. Descriptive analysis was performed to evaluate biofilm composition and differences between groups were checked with the Mann-Whitney test (p < 0.05). After one week, multispecies biofilms showed a similar pattern of bacterial composition on all analyzed implant surfaces. The most prevalent bacterium was V. parvula (similar to 50% of the total biomass), followed by S. gordonii (similar to 30%), F. nucleatum ssp. polymorphum (similar to 10%) and A. naeslundii (<5%). Total bacterial biomass was significantly higher in both grade-4-titanium surfaces (p < 0.05). The results demonstrated that not only implant surface treatment, but also titanium purity, influence early bacterial colonization.