Endodontic pathogens: propagation of infection through patent dentinal tubules in traumatized monkey teeth

Periapical pathology indicating endodontic infection, when present in marginal periodontitis-affected teeth, has recently been shown to be an aggravating factor in progression of marginal destruction. This has been associated with patency of dentinal tubules in the tooth cervix, an area normally devoid of cementum following periodontal therapy. These studies are, however hampered by that only circumstantial evidence such as presence of periapical destruction have been applied as criteria of endodontic infection. The purpose of the present investigation was to study to what extent a predefined selection of endodontic pathogens inoculated in the root canal can influence periodontal pathology and healing in areas of the root covered by or devoid of cementum, using root resorption as a histomorphometric marker. Exposed dentine surfaces, in the present study showed significantly larger areas of resorption in infected roots compared to non-infected roots, while cementum surfaces showed an almost identical distribution of tissue reactions regardless of root canal infection or not. It was concluded that endodontic pathogens or their products were not able to penetrate the cementum barrier. The significantly larger areas of resorption on exposed dentine surfaces in infected roots compared to non-infected roots indicated that endodontic pathogens or their products could spread through dentinal tubules to a root surface void of cementum. Extrapolated to the marginal situation this indicated that endodontic pathogens in the root canal might be able to aggravate marginal infection in areas of root devoid of cementum.