“…Studies have demonstrated that tubule invasion is associated with specific bacterial cell wall-polypeptide interactions with unmineralized collagen (Love et al 1997) and other bacteria (Love et al 2000), and bacterial interactions with various molecules found in tissue fluid, dentinal fluid and saliva (Love 2001(Love , 2002. The presence of an appropriate nutritional supply in the environment influences bacterial growth (Loesche et al 1983, ter Steeg et al 1987 and may influence disease progression. Studies examining the bacterial flora of carious coronal dentine show that facultative species that primarily obtain energy from fermenting carbohydrates, for example Streptococcus spp., are mainly located in superficial dentine whilst fastidious obligate anaerobic bacteria that can metabolize host-derived amino acids and peptides, such as Peptostreptococcus micros and Prevotella intermedia, are located in deeper dentine (Edwardsson 1987, Ozaki et al 1994.…”