X smart plus

Thirty premolars were shaped with the iRace rotary instruments (FKG dentaire, Switzerland) reaching a final continuous 4% taper up to tip size 30, using the following files sequence: iRace tip size 10/.02 taper, iRace tip size 10/.04 taper, iRace tip size 15/.04 taper, iRace tip size 20/.04 taper, and iRace tip size 30/.04 taper. Instruments were used with an endodontic motor (X-Smart Plus, Dentsply Maillefer) following the manufacturer's instruction in continuous rotation at 600 rpm speed and with a maximum torque set at 2.0 N, with light apical pressure. During the shaping procedure, a #10 K-flexofile was taken to the WL to check patency, and irrigation with 2.5 mL of 5.25% NaOCl was performed with a syringe and an endodontic needle in each root canal after each instrument used.

A ProTaper instrument (Dentsply Tulsa Dental Specialties, Johnson City, TN, USA) was used in a 16:1 gear reduction handpiece powered by a torque-controlled electric motor (X-Smart Plus; Dentsply Maillefer). A consistent rotation speed of 300 rpm was used in a crown-down manner involving a gentle in-and-out motion according to manufacturer's instructions. A shaping file (S1) was passed apically to within 2 mm of the working length, and SX files were then used until resistance was felt (4–5 mm from working length), followed by the use of the ProTaper instrument to carry the S1 and S2 until the full working length was achieved. The apical one-third was finished by passing the F1, F2, and F3 until the working length was reached. The instruments were used in a pecking motion and were regularly cleaned to remove debris from the flutes. Once the instrument had been passed to the end of the canal and could be rotated freely, it was subsequently removed. At this point, the next instrument in the sequence was used.[27 (link)]

A total volume of 2 mL contrast solution was injected into the canals with a syringe and 30G needle. The EC insert was inserted passively into the WL and activated by the X-Smart Plus (Dentsply Maillefer, Balaigues, Switzerland) in the reciprocating movement as recommended by the manufacturer using the WaveOne program. The irrigation method was identical to the PUI group.

Glide path in sixty training blocks was established till #20 hand files using NITIFLEX^® (Dentsply Maillefer, Ballaigues, Switzerland). Glyde™ File Prep (Dentsply Maillefer, Ballaigues, Switzerland) was used as a lubricant before the utilization of each instrument, and saline was used for irrigation during preparation. A SAF 1.5 mm file (ReDent-Nova, Israel) was introduced into the canal to the apex, using an RDT3 handpiece head (ReDent-Nova, Israel) with a torque control motor (X-smart Plus™, Dentsply Maillefer, Ballaigues, Switzerland,) at a frequency of 83.3 Hz (5000 movements per minute) with an amplitude of 0.4 mm. It was used for 4 min in a pecking motion according to manufacturers’ instructions. The SAF was connected to a VATEA System Irrigator (ReDent-Nova, Israel) that pumped saline at the rate of 5 mL/min in a continuous flow. A total of 20 mL saline was used for each root. No accurate final diameter or taper of the preparation could be assumed because the SAF has no specific size or taper.

The samples in this group were instrumented using PT rotary files (Sx-F4; Dentsply Maillefer) with a preprogramed X Smart Plus (Dentsply Maillefer) at 300 rpm speed and 2-Ncm torque. The coronal third was preflared using Sx, followed by sequential files till working length (WL) S1 (#17.06), S2 (#20.06), F1 (#20.07), F2 (#25.08), F3 (#30.09), and F4 (#40.06). Before introducing a new file each time, the root canal was irrigated with 3 ml of 5.25% sodium hypochlorite (NaOCl) and recapitulated with a #15 K-file, and then the subsequent rotary file was introduced. Ethylenediaminetetraacetic acid (EDTA) paste (RC Help, Prime Dental Products, Mumbai, India) was used as lubricant for the file with every reinsertion.

New size 25 files of the systems studied were selected (n=30 per system, total 300). The systems were divided into groups in alphabetical order (Table 1).
The instruments were rotated using X-Smart Plus endo motor (Dentsply Maillefer, Ballaigues, Switzerland) (Fig. 1) at the speed and torque recommended by manufacturers. The speed and torque of each group using only the size 25 files of endodontic systems were:
The instruments were firmly held with clamping mechanism (Fig. 2) with passive adjustment and without pressure in a stainless-steel block containing an artificial canal with the following characteristics: 60º curvature, radius of curvature 3.5 mm, length 21 mm, width 2 mm, and depth 3 mm. The characteristics of model were similar to the block used by Gambarini et al. (17 (link)) and Champa et al. (18 (link)). The canal was lubricated with glycerin after each file.
The time was calculated in seconds (s) until fracture. The number of cycles to fracture (NCF) was calculated by the following formula: (Resistance (s) x Speed)/60. The separated fragment lengths were measured with a digital Vernier caliper (Fig. 3).
Statistical analysis was performed with the SPSS 18 programme at a 95% confidence level, using the Levene´s Test to compare variances, the Welch’s Test to compare means, and the Games-Howell´s Test to reveal differences between groups.