Microbiome Changes during Regenerative Endodontic Treatment Using Different Methods of Disinfection

INTRODUCTION: The purpose of this study was to characterize qualitatively and quantitatively the changes in the endodontic microbiome, in teeth with necrotic pulp, open apexes, and apical periodontitis, with 3 antimicrobial protocols, undertaken in a multicenter clinical trial. METHODS: Microbiological samples were collected from 116 regenerative endodontic teeth, and 97 qualified for inclusion. The teeth were randomly divided into 3 treatment groups: apexification (APEX), regeneration (REGEN), and revascularization (REVASC), all in 2 appointments. The group variables in the first appointment irrigants, and second appointment irrigants and medicaments were as follows: APEX: 5.25%-6% NaOCl, 5.25%-6% NaOCl + 17% EDTA and calcium hydroxide; REGEN: 1.25% NaOCl, 17% EDTA, and 0.1 mg/mL triple antibiotic paste (TAP); and REVASC 5.25% NaOCl, saline, and 1 g/mL TAP, respectively. Sampling was done upon access (S0), after irrigation in the first appointment (S1), and after using medication and irrigation in the second appointment (S2). RESULTS: Quantitative polymerase chain reaction analysis of the 16S ribosomal RNA gene showed significant reduction in bacterial load from S0 to S2 in all groups; however, the APEX and REVASC groups had significantly less residual DNA than the REGEN group (P = .0045). The relative abundance of Bacteroidetes, Fusobacteria, Spirochaetes, and Synergistetes were reduced with the treatment rendered. However, relative abundance of Firmicutes and Actinobacteria was not changed, and that of Proteobacteria increased. LEfSe analysis showed that reduction in bacterial taxa was more in REVASC than APEX, which in turn was more than in REGEN. CONCLUSION: Enhanced antimicrobial protocols lead to better reduction in quantitative and qualitative parameters of the endodontic microflora.