Light emitting diode assessment of dentinal microcracks after root canal preparation with 4 different heat-treated file systems

BACKGROUND: The purpose of this research was to evaluate the dentinal microcracks formation after root canal prepa-ration with Hyflex (R) EDM ([electrical discharge machining], Coltene; Altstatten, Switzerland), Neolix Neoniti A1 EDM (Neolix; Beijing, China), Wave One Gold (Dentsply Sirona; York, PA, USA) and Edge File (R) X1 (EdgeEndo; Albuquer-que, NM, USA) under illumination and magnification. METHODS: One hundred fifty mandibular molars with 2 different mesial canals extracted for periodontal reasons were included in the study. The samples were decoronated at 15 mm from the apex using a carborundum disc under copious water cooling. Access opening was done using a round bur. Sectioning of the distal root was done. Patency of mesial canals were checked using a 10 K file. The samples were randomly divided into 5 groups using simple randomization technique: group 1 (uninstrumented group); group 2 (Hyflex (R) EDM [HEDM] [Coltene]); group 3 (Neolix Neoniti A1 [NA1] [Neolix]); group 4 (Wave One Gold [WOG] [Dentsply Sirona]); and group 5 (Edge File (R) X1 [EFX] [EdgeEndo]). Biomechanical preparation in all groups was done following the manufacturer's instructions. Sectioning was done at 3 mm, 6 mm, and 9 mm from the apex using a 0.13 mm circular saw under copious water cooling. Sections were observed at 16x magnification under the dental operating microscope and illumination using a light emitting diode (LED) curing light. The chi(2) test was used to determine the statistically significant differences at P<0.05. Intergroup comparison was done by the post-hoc Tukey test. RESULTS: Total of 1800 images were analyzed. The highest number of cracks was seen in Neoniti A1 group (43.33%) while the least number of cracks were seen with Wave One Gold group (13.33%). There was statistically difference be-tween reciprocating groups and the rotary group. CONCLUSIONS: Within the limitations of this study, it can be concluded that all the heat-treated file systems produced dentinal microcracks. Rotary group (NA1 and HEDM) produced significantly more cracks than reciprocation group (WOG and EFX).