Effect of Blue Heat Treatment on Vertical Force Induced with Endodontic Files

To evaluate the vertical forces induced with Reciproc (R) and Reciproc Blue (RB) systems during canal shaping.

Maxillary premolar teeth with two separate straight and constricted canals were chosen (n=26). After access cavity preparation, each tooth was fixed in a standing position on a stage connected to a force analyzing device (M5-20 Advanced Digital Force Gauge; Mark-10 Corporation, NY, USA). The glide path was prepared manually until K file sizes #15. Then, canals in all the groups were completely shaped with an R25/RB25 file (size 25,.08 taper). The canal shaping was done with a steady and gentle pressure on the file to give a slow 'in-and-out' movement of 2 mm amplitude. The file was inserted three times until it reached the WL successfully. After each insertion, the canal was recapitulated and irrigated with a 1% sodium hypochlorite solution. The shaping time was analyzed by Student's t-test. The inward and upward peak forces were used for analysis by using the Mann-Whitney test. All statistical analyses were performed using SPSS software at a 95% confidence level.

Each root canal was shaped successfully with a single file inserted three times until the WL was reached. Within each group, the overall real-time force increased with the successive insertions of the file. The inward peak forces in both groups ranged from 1.71 to 8.38 N and the R group showed minimal peak forces than the RB group in the three insertions (P<0.05). The upward peak forces ranged from 1.50 to 3.26 N wherein both groups showed comparable peak forces at each insertion (P>0.05). The R and RB systems required average times of 22.01±3.08 and 23.93±4.15 s, respectively, to shape the canals completely (P>0.05). In this experiment, no file fracture took place during canal shaping.

The blue heat treatment influenced the forces developed during canal shaping. RB file was associated with higher inward peak forces than R file.