Bacterial status in root-filled teeth exposed to the oral environment by loss of restoration and fracture or caries--a histobacteriological study of treated cases

AIM: To describe histological and microbiological findings in teeth where root fillings had been exposed to caries and the oral environment for a prolonged period. METHODOLOGY: For inclusion in the study, only teeth with a follow-up period of 3 years or more and those that had been without proper restoration for at least a period of 3 months were considered. Some root fillings had been without restoration for several years. In all, 39 roots representing 32 teeth were examined by histology. RESULTS: The majority of the specimens were without a discernible periapical bone lesion as assessed by radiography. Osteolytic lesions were seen with five roots. Longitudinal tissue sections stained with a modified Brown/Brenn staining technique revealed presence of stainable bacteria in abundance at the canal entrance and in dentinal tubules but were absent mid-root and apically in all but two specimens. Soft tissue attached to the root tip and in apical ramifications displayed distinct inflammatory cell infiltrates, suggesting microbial exposure in 7 of the 39 roots examined. In all other specimens, inflammatory cell infiltrates were either nonexistent or sparse and then associated with extruded sealer material. CONCLUSIONS: Well-prepared and filled root canals resist bacterial penetration even upon frank and long-standing oral exposure by caries, fracture or loss of restoration.