Observation of bacteria and fungi in infected root canals and dentinal tubules by SEM.

The aim of this study was to observe the root canal flora and possible penetration of microorganisms into dentinal tubules in teeth with necrotic pulps. Ten infected maxillary and mandibular molars with periapical lesions were extracted and fixed in 2.5% phosphate-buffered glutaraldehyde solution for nine days. After separation from the crowns, longitudinal grooves were cut in the roots, and they were split into two halves. The specimens were prepared for SEM. The root canals and the dentinal tubules of the fractured dentin were scanned systematically from the cervical to the apical area of the root. Cocci and rods were seen in 6 specimens. Penetration of bacteria into the dentinal tubules ranged from 10 to 150 microns. In 4 specimens, the root canals were heavily invaded by yeasts. The antimicrobial effect of routinely used endodontic disinfectants also on yeasts may be considered in persistent root canal infections.