RESUMEN
AIMS: To determine the efficacy of a single session protocol (SSP) in the reduction of septic content of primary teeth root canals and identify the persistence of bacterial species associated with unsuccessful treatment. METHODS: Primary teeth root canals (16) with pulp necrosis and peri-radicular lesions were treated. Samples were collected at baseline (T1), and after chemo-mechanical preparation, before filling (T2). Identification of the microorganisms was determined using checkerboard DNA-DNA hybridisation. STATISTICAL ANALYSIS: Wilcoxon test was applied for comparison of mean number of species, proportion and mean count of each species between the evaluation times. RESULTS: Significant reductions were found in the mean number of bacteria species between T1 and T2 (p < 0.05), but not for the reduction in proportion (p > 0.05). There was a reduction (6.0-4.6) of the mean number of species associated with failure, without statistical significance. CONCLUSION: The SSP was capable of significantly reducing the septic content, even though, many of the bacteria associated with failure persisted at the time of root canal filling.