Characterization of an Ex Vivo Model for the Assessment of Root Canal Disinfection

Abstract

Root canal bacteria in teeth with apical periodontitis were enumerated after extraction and incubation. Canals in 36 teeth were sampled after: S1, incubation for 2 hours (group A), 2 days (group B), 4 days (group C), and 6 days (group D); S2, subsequent incubation for 1 week; S3, canal disinfection; and S4, final incubation for 1 week. Bacterial concentrations were determined by culture (colony-forming unit [CFU]) and epifluorescence-microscopy (EFM) and compared by using pairwise and exact-permutation tests (p < 0.05). CFU counts were lower than EFM counts. CFU counts in S1 were higher in Gp A than in Gp C (p < 0.004) and Gp D (p < 0.02). EFM counts in S1 were higher in Gp A than in Gp C (p < 0.02). Both enumeration methods showed bacterial counts decreasing from S1 to S2 (p < 0.04). EFM was superior to culture in this ex vivo model. The indigenous flora survived incubation for 6 days, but the adverse effect of initial access would preclude testing of disinfection protocols that require two sessions.