Protaper next ptn

Each block was scanned by micro-CT (ScanXmate-D100SS270; Comscantecno, Kanagawa, Japan) before canal preparation under the following settings: 23.7 µm at 65 kV and 100 µA. During scanning, stage position conditions were standardized. Blocks were scanned at the same position using a pedestal made from silicone rubber impression material and a plastic container. Scanned blocks were confirmed to contain a glide path with the #15 21 mm K-file (MANI, Tochigi, Japan) and a working length of 9 mm was established. The circumference of the blocks was covered by opaque tape to mask the root canal system, and blocks were then randomly divided into four groups of six blocks each and instrumented as follows: stainless steel K-files (SSK), Self-Adjusting File (SAF; ReDent Nova, Ra’anana, Israel), ProTaper NEXT (PTN; Dentsply Maillefer, Ballaigues, Switzerland) and RECIPROC (REC; VDW, Munich, Germany). Based on Paqué et al. [22 (link)], the apical preparation was to a size #25. Canals were always filled with distilled water and all canal preparations were completed by one operator following the manufacturers’ instructions.

The working length of the specimens was established using a size 10 K-file (Mani. Tochigi, Japan). Hand K-files (Mani) up to size 25, using 5.25% sodium hypochlorite (NaOCl) as the irrigant, were used for the achievement of the initial glidepath for all root canals. The specimens were then randomly divided into 3 groups based on the intended instrumentation protocol (n = 60): group 1: ProTaper NEXT (PTN, Dentsply Maillefer, Ballaigues, Switzerland), up to X4 size; group 2: WaveOne “large” file (WO, Dentsply Maillefer); group 3: Self-adjusting File, 2 mm diameter (SAF, ReDent, Raanana, Israel).
The instruments were used according to the manufacturers’ instructions, including irrigation protocols during instrumentation, as recommended by each of the manufacturers. During these procedures, 5.25% NaOCl was used as the irrigant. Irrigation during canal instrumentation in the ProTaper NEXT and WaveOne groups was performed using a syringe and a 31 G side-port needle (Ultradent, South Jordan, UT, USA). In the SAF group, irrigation was performed through the hollow file using a VATEA irrigation pump (ReDent), which is an integral part of the SAF system. The volume of irrigating solution and irrigation time during canal instrumentation were standardized to a total of 16 mL and 4 min, respectively, for all instrumentation methods.