Biofilm formation on dental implants with different surface micro-topography: an in vitro study.

Objectives To compare biofilm formation on whole dental titanium implants with different surface micro-topography. Methods A multispecies in vitro biofilm model consisting of initial (Streptococcus oralis and Actinomyces naeslundii), early (Veillonella parvula), secondary (Fusobacterium nucleatum) and late colonizers (Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans) was grown for 96 hr on sterile titanium dental implants with either minimal (S-a: 0.5-1.0 mm) or moderate-roughness titanium surfaces (S-a: 1.1-2.0 mm). The resulting biofilms were studied with Confocal Laser Scanning Microscopy (CLSM) and Scanning Electron Microscope. Concentrations (colony-forming units per mL [CFU/ml]) of each bacterium were measured by quantitative Polymerase Chain Reaction (qPCR) and compared by Student t tests. Results A biofilm, located mainly at the peak and lateral areas of the implant threads, was observed on both implant surfaces, with a greater biomass and a greater live/dead ratio in moderate- compared to minimal-roughness surface implants. Statistically significant higher values of total bacteria (mean difference = 2.61 x 10(7) CFU/ml; 95% confidence interval - CI [1.91 x 10(6); 5.02 x 10(7)]; p = 0.036), F. Nucleatum (mean difference = 4.43 x 10(6) CFU/ml; 95% CI [1.06 x 10(6); 7.80 x 10(6)]; p = 0.013) and A. actinomycetemcomitans (mean difference = 2.55 x 10(7) CFU/ml; 95% CI [1.07 x 10(7); 4.04 x 10(7)]; p = 0.002), were found in the moderate- compared to minimal-roughness surface dental implants. Conclusions Implants with moderate-roughness surfaces accumulated more bacterial biomass and significant higher number of pathogenic bacteria (F. nucleatum and A. actinomycetemcomitans), when compared to implants with minimal-roughness surfaces, within a similar biofilm structure.