Ecological Differences between Untreated and Root Canal Treated Teeth

The untreated infected root canal is an environment that provides micro-organisms with nutritional diversity in a shifting pattern over time. The available nutrients are mainly peptides and amino acids, which favour anaerobic proteolytic species.

These microbes endure a static environment and starvation, but with some luck may encounter a serum like fluid transudate from the periapical tissue. The species that persist are those that either have survived the antimicrobial treatment, or have entered during treatment and found it possible to establish where others cannot do so. Where the coronal seal is defective or missing, there is the possibility for new infection of the root canal space.

Species commonly associated with persistent intraradicular infection such as Candida and Enterococci can be viewed as opportunistic pathogens.

In general, micro-organisms involved in persistent infections implement one of three strategies to evade the immune response — sequestration, cellular or humoral evasion.

• Sequestration involves a physical barrier between the microbe and the host (E.faecalis and Candida).
• Cellular evasion means that micro-organisms avoid leukocyte dependent antibacterial mechanisms.
• Humoral evasion means that those extracellular bacteria avoid the host's antibodies and complement.