Quantitative evaluation of apically extruded debris with different single-file systems: Reciproc, F360 and OneShape versus Mtwo.

AIM: To assess in a laboratory setting the amount of apically extruded debris associated with different single-file nickel-titanium instrumentation systems compared to one multiple-file rotary system. METHODOLOGY: Eighty human mandibular central incisors were randomly assigned to four groups (n = 20 teeth per group). The root canals were instrumented according to the manufacturers' instructions using the reciprocating single-file system Reciproc, the single-file rotary systems F360 and OneShape and the multiple-file rotary Mtwo instruments. The apically extruded debris was collected and dried in pre-weighed glass vials. The amount of debris was assessed with a micro balance and statistically analysed using anova and post hoc Student-Newman-Keuls test. The time required to prepare the canals with the different instruments was also recorded. RESULTS: Reciproc produced significantly more debris compared to all other systems (P < 0.05). No significant difference was noted between the two single-file rotary systems and the multiple-file rotary system (P > 0.05). Instrumentation with the three single-file systems was significantly faster than with Mtwo (P < 0.05). CONCLUSIONS: Under the condition of this study, all systems caused apical debris extrusion. Rotary instrumentation was associated with less debris extrusion compared to reciprocal instrumentation.

Shaping ability of different single-file systems in severely curved root canals of extracted teeth.

AIM: To compare the shaping ability of three different single-file systems with Mtwo rotary instruments during the preparation of curved root canals in extracted teeth. METHODOLOGY: A total of 80 root canals with curvatures ranging between 25° and 35° were divided into four groups of 20 canals. Based on radiographs taken prior to instrumentation, the groups were balanced with respect to the angle and the radius of canal curvature. Canals were prepared to the following apical sizes: Mtwo: size 30 using the single-length technique; Reciproc, F360, and OneShape: size 25. Using pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis programme. Preparation time, changes in working length, and instrument failures were also recorded. These data were analysed statistically using anova and Student-Newman-Keuls test. RESULTS: During preparation, no file fractured. All instruments maintained the original canal curvature well with no significant differences between the instrument systems (P = 0.792). Instrumentation with Reciproc and OneShape was significantly faster than with F360 and Mtwo (P < 0.05), while F360 was significantly faster than Mtwo (P < 0.05). No significant differences were obtained regarding changes in working length during instrumentation with the different instruments (P = 0.784). CONCLUSIONS: Under the conditions of this study, all instruments respected the original canal curvature well and were safe to use. The use of Reciproc and OneShape instruments required less time to prepare the curved canals compared with Mtwo and F360.