Disinfecting and Shaping Type I C-shaped Root Canals: A Correlative Micro-computed Tomographic and Molecular Microbiology Study.

INTRODUCTION

This ex vivo study compared the disinfection and shaping abilities of 2 preparation protocols in C-shaped canals.

METHODS

Mandibular second molars with type I C-shaped canals were pair matched based on micro-computed tomographic (micro-CT) analysis and distributed into 2 groups. The canals were contaminated with a mixed bacterial culture and prepared using 2 protocols, both with 2.5% sodium hypochlorite irrigation: XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) supplemented with XP-endo Finisher (FKG Dentaire) (XP-E) and BioRaCe (FKG Dentaire) supplemented with a Hedström file (Dentsply/Sirona, Tulsa, OK) (BR-Hed). Micro-CT scans and intracanal bacteriologic samples were taken before (scan #1 and sample 1) and after preparation (scan #2 and sample 2) and after the supplementary step (scan #3 and sample 3). Canal shaping was evaluated by micro-CT imaging, and disinfection was assessed by quantitative polymerase chain reaction.

RESULTS

Micro-CT data from the XP-E (n = 21) and BR-Hed (n = 23) protocols revealed no significant differences between groups regarding shaping parameters (canal volume, surface area, structure model index, and prepared walls) after preparation and after the supplementary step (P > .05). All these parameters significantly increased after each preparation step (P < .05), except for structure model index changes after the XP-endo Finisher (P > .05). Bacteriologic data from the XP-E (n = 21) and BR-Hed (n = 22) groups showed that 14 (66.7%) and 10 (45.5%) S2 samples still had detectable bacteria, respectively. The corresponding figures for supplementary steps with the XP-endo Finisher and Hedström file were 11 (52.4%) and 10 (45.5%), respectively. Bacterial counts in sample 1 significantly decreased in samples 2 and 3 in both groups (P < .01). Intragroup comparison between sample 2 and sample 3 showed a 66% reduction in counts after using the Hedström file and 18% after using the XP-endo Finisher (P > .05 for both groups). The quantitative bacterial reduction was not different between groups (P > .05).

CONCLUSIONS

The XP-endo Shaper and BioRaCe systems have similar disinfecting and shaping abilities in C-shaped canals. Supplementary steps with the Hedström file and the XP-endo Finisher were similarly effective in improving shaping, but this was not sufficient to enhance disinfection. About half of the cases, in both groups, still harbored detectable amounts of bacteria.