Microbiological analysis of endodontically treated teeth with apical periodontitis before and after endodontic retreatment

Objective To characterize the microbiota of teeth with endodontic treatment failure by 16S ribosomal RNA genetic sequencing (GS) and PCR at the different phases of the endodontic retreatment and to associate the presence of specific bacteria with clinical and radiographic features in teeth with apical periodontitis. Materials and methods Twenty infected root canals of single-rooted teeth were selected. Samples were collected with sterile paper points before chemo-mechanical preparation (CMP) (S1), after CMP (S2) and after 30 days of intracanal medication (ICM) (S3). Microbial identification was performed using GS and PCR. Tukey-Kramer post hoc test and post hoc ANOVA were used for intergroup analysis. Pairedttest and repeated-measures ANOVA were applied for intragroup analysis, at a significance level of 5%. Results A total of 89 strains were identified using GS. Sixty-five strains were recovered in S1 and 15 strains in S2, and 9 strains remained in S3.Enterococcus faecaliswas the most predominant bacteria. Gram-positive cocci bacteria predominated. Gram-negative species were also detected. Using species-specific PCR primers to detect seven species, the most prevalent ones at all the phases of the endodontic retreatment wereE. faecalisandPorphyromonas gingivalis. However,Parvimonas micraandP. gingivaliswere associated with previous pain,P. gingivaliswas associated with tenderness to percussion andE. faecalis,Fusobacterium nucleatumandP. gingivaliswere associated with periapical lesion > 3 mm. Conclusions In conclusion, the microbiota of persistent infection is polymicrobial with predominance ofE. faecalisandP. gingivalisin all phases of the endodontic retreatment, regardless of the method used for microbial identification. Associations were found between specific bacteria and clinical/radiographic features.

Automated summary

The study found that the microbiota of teeth with endodontic treatment failure is polymicrobial, with Enterococcus faecalis and Porphyromonas gingivalis predominating in all phases of retreatment. Specific bacteria were associated with certain clinical and radiographic features.