Figure 1.

Scanning electron microscopic images of the apical of the apical foramen of a tooth showing a mature biofilm of (i) Leuconostoc spp. (10,000×). A multilayered polymeric matrix is evident. Also noticed are communicating channels in the biofilm (A), extracellular fibers secreted by bacterial cells (B), metabolically active cells characterized by cell division (C) and compact extracellular polymers (D); (ii) Biofidobacterium spp. in a maturation state (10,000×). Secretion of polymers in granular form by the bacterial cells (A), microfilaments of extracellular polymers surrounding the rod shape of the microorganism (B) and extracellular polymers in the maturation state (C) can be seen (Courtesy: Dr. Ana Maria González Amaro, Maria Verónica Méndez González, UASLP Mexico).