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

Abstract 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.