Molecular Microbiological Analysis of ProTaper Next, XP-Endo Shaper and Reciproc Blue systems in severely curved canals

Aim: This study evaluated the effectiveness of the mechanical reduction of intracanal bacteria produced by the endodontic systems Reciproc Blue (VDW GmbH), XP-Endo Shaper (FKG Dentaire) and ProTaper Next (Dentsply Sirona Endodontics) in severely curved canals by means of a molecular microbiological analysis. Methodology: A total of 42 severely curved mesiobuccal canals of human permanent mandibular molars were selected and prepared. Then, canals were contaminated with Enterococcus faecalis strains (ATCC 29212) by incubation during 21 days at 37 oC for formation of a mature biofilm. After that, contaminated specimens were randomly divided into 3 groups (n=14): ProTaper Next (G1), XP-Endo Shaper (G2) and Reciproc Blue (G3). Microbial samples were obtained before (S1) and after root canal preparation (S2). Analyses of intracanal E. faecalis reduction was performed using quantitative polymerase chain reaction (qPCR), and the differences between groups was analyzed by Kruskal-Wallis test. Significance level was set at P<0.05. Results: All systems presented effective bacterial reduction, but still had bacterial growth. No significant difference between the evaluated file systems was demonstrated (P>0.05). Conclusions: ProTaper Next, Reciproc Blue and XP-Endo Shaper presented similar mechanical reduction of intracanal bacteria. No file system was capable of rendering severely curved canals completely free from bacteria.