comparison of dentinal crack formation with reciproc, mtwo and protaper root canal preparation systems

Background: instrumentation with rotary instruments could potentially cause dentinal cracks possibly leading to tooth fracture. reciproc files require a single file to finalize the root canal preparation and the effect of this procedure has not been compared with other systems. objectives: the aim of this study was to compare the incidence of dentinal micro-cracks following root canal preparations with protaper, mtwo and reciproc files. materials and methods: in an experimental in vitro trial, 80 maxillary and mandibular first molars were selected and their crowns and distal roots were cut. the roots were then examined to remove any previous cracks and defects. an impression polyether materialwasused to simulate teeth periodontal ligament (pdl). the teeth were divided to four experimental groups (n=20)andprepared using reciproc, mtwo and protaper or remained unprepared as a control group. the specimens were then sectioned horizontally on 3, 5 and 9mmfrom the apex and number of micro-cracks was determined by stereomicroscope. the incidence of dentinal cracks on different systems or sections were statistically analyzed by means of the chi-square test. results: dentinal defects on 3-mm, 5-mm and 9-mm sections from the apex were noted in 10 (5.6%); 7 (3.9%) and 9 (5.0%) samples of all, respectively. following canal preparation using reciproc, protaper and mtwo systems, the defects were observed in 7 (3.9%), 12 (6.7%) and 7 (3.9%) the sections, respectively. no significant differences were observed regarding the defect incidence on the studied instrumentation files or sections. conclusions: regarding the study limitations, dentinal cracks were observed in all files and distances from the apex. although there was more crack incidence in protaper files, no significant differences were noted regarding the studied systems and sections from the apex.