Ecology of pulpal and periapical flora

Inflammatory lesions in the periapical tissues of the teeth are a result of root canal infection following partial or complete breakdown of the pulp. Infected root canals have a complex microbial flora consisting of cocci, rods, spirochaetes, filaments and fungi which may exist as a loose collection in mist canal lumen or as dense aggregates (biofilms) adhered to dentinal walls. The biofilm environment has been found to be advantageous for bacterial living; as it helps the bacteria to survive and multiply, inducing their metabolic products that will lead in the persistence of periapical infection.