Effect of tissue fluids on hydrophobicity and adherence of Enterococcus faecalis to dentin

This in vitro study was carried out to determine (1) the hydrophobicity of selected oral bacteria, (2) the influence of growth media (saliva and serum) and mode of growth (planktonic or biofilm) on the hydrophobicity of Enterococcus faecalis, and (3) the influence of growth media and conditioning fluids on the adherence of E. faecalis to dentin. The ability to bind to a hydrocarbon phase (xylene) was used as an index of relative hydrophobicity of cells. Fluorescent microscopy-based technique was used to assay the bacterial adherence to dentin. Results showed that bacteria involved in the primary stage of oral biofilm formation such as Streptococcus mutans, Fusobacterium nucleatum, and Porphyromonas gingivalis are relatively more hydrophobic than E. faecalis. The hydrophobicity of E. faecalis was significantly increased during starvation and biofilm mode of growth (p <.05). The adherence of E. faecalis to dentin was appreciably increased after starvation and when dentin was conditioned with saliva. It was observed that surface conditioning of dentin with saliva and starvation can enhance the adherence of E. faecalis to dentin. The findings from this study indicated that the coronal leakage of saliva and the physiologic state of microbes might play an important role in the adherence and biofilm formation of bacteria to root canal dentin.