The modulating effect on Staphylococcus species and Pseudomonas aeruginosa biofilm development of salivary pellicle conditioning titanium surfaces

Objectives To evaluate the modulating effect of salivary pellicle (SP) on titanium (Ti) surfaces on the development of Staphylococcus species and Pseudomonas aeruginosa biofilm. Materials and Methods Ti substrates were incubated for 2 hours with whole saliva samples to induce the salivary pellicle formation. After conditioning with SP, Ti substrates were incubated for 12 hours with P. aeruginosa , S. aureus , S. epidermidis strains individually, in addition to co-culture of the three bacteria. The biofilm development on the Ti substrates was visualized by scanning electron microscopy (SEM). To measure the metabolic activity and vitality of cells within the biofilm the XTT assay was used, while the proportion of the species tested in the biofilms was determined throughout DNA-DNA hybridizations (checkerboard). Results Salivary pellicle modulated the biofilm development on the Ti surfaces, favouring the formation of P. aeruginosa biofilms, while inhibiting the growth of S. aureus and S. epidermidis . In the case of the coculture biofilms, a predominance of P. aeruginosa cells over the Staphylococcus strains was observed. Conclusions When the bacterial strains were tested individually, the SP importantly reduced the development of biofilms of Staphylococcus species, whereas it favored the development of P. aeruginosa biofilms on Ti surfaces. Similarly, when mixed biofilms developed, SP favored the selective expansion of P. aeruginosa and S. aureus growth over S. epidermidis growth. Clinical relevance: The results of this study provide valuable information on the modulatory effect of the SP on the development of opportunistic bacteria biofilms on Ti surfaces used for dental and oral implantology.