title: Evaluation of dentinal defect formation after root canal preparation with two reciprocating systems and hand instruments: anin vitrostudy.
abstract: The purpose of this study was to evaluate the presence of dentinal defects after root canal preparation with hand instruments and two different reciprocating instruments. Sixty freshly extracted mandibular incisor teeth were selected for thisin vitrostudy. On the basis of root length, mesiodistal and buccolingual dimensions, the teeth were allocated into three identical experimental groups (n= 15) and one control group (n= 15). The teeth in the control group were left unprepared. The other groups were: stainless steel hand instruments, WaveOne® Primary instruments and RECIPROC® R25 instruments. The reciprocating instruments were used with a reciprocating gentle in-and-out motion in a torque-limited electric motor at the appropriate preset mode. Horizontal sections were made 3, 6 and 9 mm from the apex. Samples were stained with methylene blue and viewed through a stereomicroscope. The presence of dentinal defects (fractures, incomplete cracks and craze lines) and their locations were investigated by two endodontists. These data were analysed statistically by Fisher's exact and chi-square tests. No defects were observed in the unprepared group. All instruments caused dentinal defects, with no significant differences between the instrument systems. All experimental groups demonstrated significantly more defects at the 3-mm level in comparison with the unprepared group (p= 0.032). At the other levels, there was no significant difference between the experimental groups and the control group. The use of hand or reciprocating instruments could induce the formation of dentinal defects during root canal preparation.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Kocaeli University , Kocaeli , Turkey.
authors.forename: Dilek
authors.initials: D
authors.lastname: Helvacioglu-Yigit
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Kocaeli University , Kocaeli , Turkey.
authors.forename: Seda
authors.initials: S
authors.lastname: Aydemir
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Istanbul University , Istanbul , Turkey.
authors.forename: Ayca
authors.initials: A
authors.lastname: Yilmaz
keywords: reciprocating instruments; root canal preparations; vertical root fracture