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Aim: The aim of the present study was to compare the shaping ability of two different nickel-titanium rotary files in the curved root canals of extracted human molar teeth., Methods: Thirty root canals of 17 extracted human molars teeth were randomly assigned to two experimental groups (n = 15): ProTaper Next and ProTaper Universal (PTU), on the basis of the rotary files system used. The final size of all apical foramina was 0.25 mm in diameter. Standardized digital radiographs were taken before and after instrumentation in both clinical and proximal views, with a size 10 K-file inserted into the canal for the determination of the angle of curvature and apical transportation. Preparation time and fractured or deformed instruments were also recorded. The unpaired Student's t-test was used to compare results., Results: There was no significant difference between the two instruments with respect to canal straightening and apical transportation before and after instrumentation (P > 0.05). The use of both instruments resulted in a significant reduction in the angle of curvature after instrumentation (P < 0.05). Instrumentation time was significantly greater for PTU (P < 0.05)., Conclusions: The ProTaper Universal and ProTaper Next systems performed similarly with regard to the straightening of curved root canals and apical transportation. ProTaper Next was significantly faster than ProTaper Universal., (© 2015 Wiley Publishing Asia Pty Ltd.)

Introduction: A final flush with chelating agents and antiseptic irrigating solutions is needed to remove the smear layer. The improvement of these protocols is possible by using specific delivery and agitation techniques. This study examined the effect of different final irrigation regimens and methods of activation on smear layer removal in curved canals after root canal instrumentation., Methodology: Mesial root canals of 50 extracted mandibular molars were prepared using ProTaper rotary files (Dentsply Maillefer, Ballaigues, Switzerland) and 3% NaOCl. Teeth were then allocated to two control groups and four experimental groups (n = 10) for final irrigation as follows: no-activation group (final rinse with a 27-gauge needle and 17% EDTA/3% NaOCl), manual-dynamic activation group (final rinse 17% EDTA/3% NaOCl + gutta-percha agitation), automated-dynamic activation group (final rinse 17% EDTA/3% NaOCl + RinsEndo [Dürr Dental GmbH & Co KG, Bietigheim-Bissingen, Germany]), and sonic-activation group (final rinse 17% EDTA/3% NaOCl + Endoactivator [Advanced Endodontics, Santa Barbara, CA]). All mesial roots were split with a new approach to allow visualization of every third of the canal, particularly the apical third. The samples were prepared for scanning electron microscopic observation to assess the smear layer removal. Blind scoring was performed by two calibrated observers using a five-score scale. The differences in smear layer scores between the experimental groups were analyzed with the Kruskal-Wallis test and the Mann-Whitney U test. The level of significance was set at p = 0.05., Results: Very high levels of root canal cleanliness (< or = score 3) were found for each test group with activation. For the middle and apical third, the no-activation group was significantly less effective than the three other activation groups (p < 0.05). The manual-dynamic activation group (final rinse 17%EDTA/3%NaOCl + gutta-percha agitation) and the sonic-activation group (final rinse 17%EDTA/3%NaOCl + Endoactivator) showed significantly better smear layer removal (p < 0.05) in comparison with the other test groups in the apical third., Conclusion: Root canal cleanliness benefits from solutions activation (especially sonic activation and manual-dynamic activation) in comparison with no activation during the final irrigation regimen., (Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Unlabelled: Crown down preparation is the most known and described technique since the introduction of Nickel Titanium (NiTi) rotary instruments in endodontics. This technique gives good results but has limitations, such as not addressing the initial anatomy of oval or dumb-bell shaped canals. The specific design of the Protaper instruments allows use of them with a different technique and, specifically, with a brushing motion in the body of the canal. The recent introduction of hand Protaper files has expanded the range of application of this system, especially in curved canals. The 'hybrid technique', using rotary and hand files, and the advantages of the combination of both instruments, are clearly described in this article. Used with this technique, the Protaper is a very safe system to use, and more controllable, for both inexperienced and experienced practitioners alike, than other systems., Clinical Relevance: To understand the precautions needed with rotary files, and how to use them to preserve the anatomy of the canal and get a tapered shaping, even in severely curved canals.