A scanning electron microscopic study on the microflora of chronic pericoronitis of lower third molars.

In nine cases of chronic pericoronitis of lower third molars, the affected teeth were carefully removed with the follicles in situ and prepared for scanning electron microscopic (SEM) study. The study disclosed great heterogeneity in the distribution and density of microorganisms on hard as well as soft tissues surrounding the pericoronal pouch. Common features were presence of discrete microenvironments with clusters of bacteria, a decrease in the number of organisms toward the bottom of the pericoronal pouch, and the high proportion of spirochetes, which tended to increase in an apical direction. The study showed leukocytic activity in all areas, and phagocytosis apparently took place on the tissue surfaces within the pericoronal space.