Aim: This in vitro study was conducted to measure and compare the incidence of dentinal defects caused by (RECIPROC blue, ProTaper Gold, ProTaper NEXT and RECIPROC) nickel titanium (NiTi) rotary instruments.Materials and methods: Seventy-five palatal roots of freshly extracted human maxillary first molars were used in this study. The total samples were randomly divided into five groups. Each group contained 15 samples (N = 15): group I: single file RECIPROC system, group II: ProTaper Next system, group III: ProTaper GOLD system, group IV: single file RECIPROC blue system and Group V: control group (No preparation). Root canal instrumentation were carried out according to manufacturer's instructions for each instrumentation system to # 40 apical size. Each root sample was sectioned horizontally at 2 mm, 4.5 mm and 7 mm, respectively from the apex. All root sections were observed under a stereomicroscope at 25X magnification. Results:The roots prepared by Reciproc showed the highest incidence of dentinal defects followed by ProTaper NEXT, ProTaper Gold then RECIPROC blue group which showed the lowest incidence of dentinal defects. The data obtained were analyzed statistically using Fisher's exact test at or equal to 5% significance levels. Fisher's exact test revealed that RECIPROC groups had a significant difference when compared with RECIPROC blue (p ≤ 0.01) and with ProTaper Gold (p ≤0.05) groups. While, other comparisons between each pair of groups revealed a non-significant difference between groups (p > 0.05). Regarding dentinal defects at different levels (apical, middle, coronal), Fisher's exact test showed that there was a non-significant difference in the incidence of dentinal defects when comparing among different levels in the same group or when comparing among different groups at the same level (p > 0.05). Conclusion:all experimental groups showed dentinal defects while no dentinal defects were observed in the negative control group.Clinical significance: the potential of root fracture is reduced using more flexible Ni Ti rotary instruments.

Background. Apically extruded debris (AED) is an inherent concern during root canal treatment for both endodontists and general practitioners. The present study investigates the AED of the novel R-Motion single-file reciprocating system compared to standard single reciprocating and multifile rotary systems. Materials and Methods. Fifty-six moderately curved palatal roots of upper maxillary first molars were selected for the present study. The samples were then divided randomly into four groups (n = 14)— Group I: R-motion (RM), Group II: WaveOne Gold (WOG), Group III: ProTaper Next (PTN), and Group IV: HyFlex EDM (HFEDM). The researcher has modified Myers and Montgomery’s method to simulate human body temperature. Vials were used to collect debris and weighted using a 0.00001 sensitive balance before and after instrumentation. The instrumentation of all experimented groups was done at 37°C, terminated at master apical file #25. An auto syringe with a side vented needle was used to deliver 8 ml of deionized water for irrigation of each sample during preparation. Vials were stored in a dry sealed desiccator which contained CaSO4 crystals, for 24 hr before weighing. The weight of the collected debris was obtained by subtracting the preinstrumentation weight from the postinstrumentation weight for each vial. The Kruskal–Wallis and Mann–Whitney U tests were performed to analyse the statistical difference in the amount of debris between the tested groups at a 0.05 significance level. Results. The RM system produced less debris extrusion than all tested groups, with a significant difference between the former and the WOG and the PTN systems. However, WOG, PTN, and HFEDM showed no statistically significant difference in the amount of AED. Conclusion. All tested groups produced apical debris in different amounts. The RM produced substantially less AED than WOG and PTN. Meanwhile, WOG, PTN, and HFEDM caused a comparable amount of AED.

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The aim of the this study was to investigate the efficacy of ProTaper rotaryinstruments compared to hand instrumentation with Hedstrom files, with and withoutthe use of a solvent (eucalyptol) in the retreatment of gutta-percha filled root canals.Roots of forty extracted single-rooted maxillary anterior teeth with straight root canalswere utilized in this study. The root canals were prepared using step-back techniqueand obturated with laterally condensed gutta-percha and sealer cement. The rootsrandomly divided into four groups with ten specimens each. Removal of gutta-perchawas performed using ProTaper and Hedstrom files, both were used with and withoutthe solvent eucalyptol. Both, time taken to reach the working length and time taken tocomplete removal of gutta-percha were recorded. Statistical analysis of the collecteddata revealed a highly significant decrease in the working time when ProTaper wasused to remove gutta-percha compared with Hedstrom files. A highly significantdecrease in the working time was found when eucalyptol was used with ProTaper. Nosignificant difference existed between the treatments using Hedstrom with or withoutthe use of eucalyptol.

The aim of this study was to investigate the effect of different irrigants (EDTA,MTAD, CHX) on the sealing ability of new Bioceramic root canal sealer. Materialand methods: A total of sixty extracted human single-rooted premolar teeth wereused. After instrumentation, teeth were randomly divided into three main groups(n=20) according to the type of final irrigants used. In group (A) 17% EDTA wasused. Group (B) irrigants was MTAD. In group (C) irrigant was 2% CHX. Each maingroup further subdivided into two subgroup (n=10) according to the type of sealerused. Subgroup (1) canals obturated with Bioceramic sealer. In subgroup (2) canalsobturated with AH plus sealer. After incubation period for one week the roots wereplaced in 2% methylene blue dye and kept in incubator for 48 hours then the rootswere cleared, dye penetration measured by stereomicroscopic. Results: statisticalsignificant difference was found between groups (p<0.001). In subgroup (1) BC sealer& CHX showed the lowest mean of leakage in comparing to other type of irrigantswith highly significance difference with BC sealer & EDTA. In subgroup (2) AH Plus& EDTA showed the lowest mean of apical leakage. A highly significance differenceswas found between subgroup (1) and subgroup (2) for all type of irrigants.(p<0.001).Conclusion: when Bioceramic sealer is used in obturation of root canalsystem, it is better to use it in combination with CHX irrigant to improve the apicalseal.