Study about the architecture and behavior of single and mixed biofilms - Fusobacterium nucleatum and Porphyromonas gingivalis - facing two different dental implants abutments materials

Abstract

Dental implant rehabilitation has become a routine procedure to replace missing teeth. Its success depends on proper osseointegration, as well as the lack of inflammation. An important factor contributing to the development of inflammation is the attachment of microorganisms and subsequent development of biofilms on the prosthetic components. This study focused on effect of materials and treatment surfaces on the bacterial adhesion and biofilm formation. We, first, assessed the biofilm formation on machined titanium (Ti) discs treated and untreated with UV-photofunctionalization. UV-treatment was performed using a photo-device for 12 minutes. Hydrophobic-to-hydrophilic conversion was confirmed on UV-treated titanium surfaces. Biofilm was formed by incubating the discs in rich medium containing a complex representative saliva-derived oral microbial community. After 3 and 16 hours, the biomass of biofilm and the bacteria profile was analyzed. For other experiments, it was used titanium and zirconia (ZrO2) discs as abutment implants and bovine enamel (BE) as a positive control. Roughness means that topography and energy-free surface analysis were performed prior to applying microbiology biofilms onto materials. Biofilms in single species with Streptococcus mutans (S. mutans), Porphyromonas gingivalis (P. gingivalis) and Fusobacterium nucleatum (F. nucleatum) and multi species with P. gingivalis and F. nucleatum were developed on each samples and quantitatively evaluated by counting forming units (CFU) and qualitatively by confocal microscopy. Also, we analyzed the development of a complex oral biofilm on two different abutments implants surfaces. Quantitatively and qualitatively analysis were performed after 16 and 48 hours of incubation under anaerobic conditions. In relation to first study, the biomass of biofilm formed on UV-treated surfaces was significantly lower than untreated surfaces. Among Ti, ZrO2 and BE surfaces, the mean roughness in all discs was d 0.21 ¼m and it did not affect the bacterial adhesion. Our results indicated a strong hydrophobic characteristic for Ti and ZrO2 whereas BE, due to its molecular structure, revealed both properties; however, after immersion of the samples in human saliva, these properties were changed. Qualitative image revealed higher density of cells onto BE surfaces than other materials. P. gingivalis single biofilm on titanium, and P. gingivalis + F. nucleatum multi-specie on zirconia, showed small amount of cells on disc surfaces. Qualitative images with confocal revealed a thin layer of multispecies biofilm on ZrO2 materials. In contrast to these outcomes, the results with a complex oral community indicated that although we found similarity on bacteria profile in both materials surfaces, the biomass of a complex oral biofilm was higher on ZrO2 than Ti materials. In conclusion, the UV-photofunctionalization treatment of titanium reduces saliva-originated biofilm formation. Our findings suggest that the material composition and the bacteria community species used for experiments have an important impact on the type of bacteria that adhered onto abutment surfaces. This information can lead to important development in strategies to create anti-microbial surfaces, and thus potentially improve outcome of implant placement. (AU)