Quantitative analysis of apically extruded bacteria following preparation of curved canals with three systems.

This study compared the amount of apically extruded bacteria following preparation of curved root canals using two continuously rotating multifile and one reciprocating single-file systems. Mesiobuccal canals from maxillary molars were contaminated with Enterococcus faecalis and divided into three groups according to the instrumentation system: Reciproc (R25 instrument, 25/.08), BT-RaCe (10/.06, 35/.00 and 35/.04), and Mtwo (25/.06, 30/.05 and 35/.04). Apically extruded material was collected by a customized apparatus with 1.5% agarose gel covering the root apex to simulate the periradicular tissues. The extruded material was extracted from the gel and subjected to bacteriological culture for bacterial quantification. The three systems showed a high frequency of bacterial extrusion (>70%). There were no statistically significant differences in the counts of extruded bacteria between groups (P > 0.05). The incidence and amount of apical bacterial extrusion were similar between the three systems. The customized apparatus was effective in collecting apically extruded bacteria.

Bacteria and Hard Tissue Debris Extrusion and Intracanal Bacterial Reduction Promoted by XP-endo Shaper and Reciproc Instruments.

INTRODUCTION: This study used a multipurpose analytic approach to compare the levels of apically extruded bacterial and hard tissue debris as well as intracanal bacterial reduction after root canal preparation with either XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) or Reciproc (VDW, Munich, Germany) instruments. METHODS: Distobuccal canals from extracted maxillary molars were contaminated with Enterococcus faecalis and randomly distributed into 2 groups according to the instrumentation system: the XP-endo Shaper or Reciproc. Teeth were mounted in an apparatus that simulates the apical resistance offered by the periapical tissues and permitted to collect debris extruded during preparation. Saline was used as the irrigant during preparation, and all treatment procedures were performed inside a cabinet under a controlled temperature of 37°C. DNA extracts from samples taken from the canal before and after preparation were subjected to quantitative real-time polymerase chain reaction for E. faecalis counting. The volume of extruded debris was evaluated by micro-computed tomographic imaging. DNA was extracted from the extruded hard tissue debris and analyzed by quantitative real-time polymerase chain reaction. RESULTS: Mechanical intracanal bacterial reduction was significantly more pronounced when using the XP-endo Shaper (P < .001). Although both instruments produced a similar volume of extruded debris (P > .05), extruded bacteria counts were significantly lower with Reciproc than the XP-endo Shaper (P < .001). No correlation was observed between the extruded bacterial counts and debris volume. CONCLUSIONS: Although bacterial extrusion was lower with Reciproc, the intracanal bacterial reduction was higher with the XP-endo Shaper. Both techniques produced a similar volume of hard tissue debris extrusion.