Neither technique was able to completely prepare the outline of long-oval canals. The Reciproc system removed more tooth structure. The BioRaCe left fewer untouched dentine walls in the more coronal thirds of the canal, whilst Reciproc left fewer in the apical third.

The aim of this study was to determine the removal of dentin produced by number 25 (0.08) Flare files (Quantec Flare Series, Analytic Endodontics, Glendora, California, USA) and number 1 e 2 Gates-Glidden burs (Dentsply - Maillefer, Ballaigues, Switzerland), in the mesio-buccal and mesio-lingual root canals, respectively, of extracted human permanent inferior molars, by means of measuring the width of dentinal walls prior and after instrumentation. The obtained values were compared. Due to the multiple analyses of data, a nonparametric test was used, and the Kruskal-Wallis test was chosen. There was no significant difference between the instruments as to the removal of dentin in the 1st and 2nd millimeters. However, when comparing the performances of the instruments in the 3rd millimeter, Flare files promoted a greater removal than Gates-Glidden drills (p > 0.05). The analysis revealed no significant differences as to mesial wear, which demonstrates the similar behavior of both instruments. Gates-Glidden drills produced an expressive mesial detour in the 2nd and 3rd millimeters, which was detected trough a statistically significant difference in the wear of this region (p > 0.05). There was no statistically significant difference between mesial and lateral wear when Flare instruments were employed.

Introduction: Rotary nickel-titanium (NiTi) instruments have become very popular in recent years mainly because they allow an effi cient preparation of the root canal system. New rotary endodontic instruments resulted from the development of new features, such as variable taper, non-cutting safety tip and variable length of cutting blades. The purpose of this study was to evaluate the degree of canal transportation observed with two nickel-titanium rotary systems, K3 (SybronEndo, Orange, CA, USA) and Mtwo (VDW, Munich, Germany), as well as their centering ability, by measuring dentin wall thickness before and after instrumentation. Methods: Thirty extracted mandibular molars were embedded in resin blocks and sectioned 3.5 and 5.0 mm short of the anatomical apex. The mesiobuccal canals were prepared with the K3 system, using instruments 0.12/25, 0.08/25, 0.06/25, 0.04/25, and 0.02/30 progressively until reaching the working length; and the mesiolingual canals were prepared with the Mtwo system, using instruments 0.04/10, 0.05/15, 0.06/20, and 0.06/25 to full working length. Pre-and postoperative sections were photographed and all data were recorded and analyzed statistically using the Mann-Whitney test. Results: Canal transportation and centering ability results were similar for both instruments (p > 0.05). Relevance: The K3 and Mtwo systems allowed the preparation of curved root canals with minimal transportation, 3.5 or 5.0 mm short of the anatomical apex.Root Canal Preparation; Dental Instruments; Dental Alloys.Avaliação do transporte apical e da capacidade de centralização de dois sistemas rotatórios de niquel-titânio • Introdução:Os instrumentos rotatórios em níquel titânio vêm se tornando populares nos últimos anos principalmente devido à sua efi ciência no preparo de canais radiculares. Novos instrumentos rotatórios resultaram do desenvolvimento de características como conicidade, pontas sem corte seguras, e variação do comprimento da lâmina de corte. A proposta deste estudo foi avaliar o grau de transporte do canal observado com dois sistemas rotatórios de níquel-titânio, K3 (SybronEndo, Orange, CA, EUA) e Mtwo (VDW, Munique, Alemanha), bem como sua habilidade de centralização, por meio da mensuração dos fragmentos de dentina da parede do canal radicular, antes e após a instrumentação. Métodos: Trinta molares inferiores foram inseridos em blocos de resina e seccionados a 3,5 e a 5,0 mm do ápice. Os canais mésio-vestibulares foram preparados com o sistema K3 utilizando-se a sequência #25.12, #25.08, #25.06, #25.04 e #30.02 progressivamente até o comprimento de trabalho; e os canais mésio-linguais foram preparados com o sistema Mtwo, utilizando-se os instrumentos #10.04, #15.05, #20.06 e #25.06 por todo o comprimento de trabalho. Secções pré e pós-operatória foram fotografadas, e todos os dados foram anotados e analisados estatisticamente utilizando-se o teste de Mann-Whitney. Resultados: Os resultados referentes ao grau de transporte do canal e à capacidade de centralização foram similares para ambos os sis...

The action of the endodontic instrument leads to hard-tissue debris. The main goal of the irrigation procedures is its removal. Nevertheless, depending on its kinematics the rotary file can contribute to the removal of hard-tissue debris. The TF Adaptive system (SybronEndo, Orange, CA) combines the rotary and reciprocating movement and the Reciproc system (VDW< Munique, Alemanha) with pure reciprocating movement, removes significant quantities of dentin of the canal wall with more difficulties of pulling out hard-tissue debris. The aims of this study were, using microcomputed tomography: evaluate preparation and quantify hard-tissue debris reduction in long-oval canals comparing TF Adaptive and Reciproc systems; evaluate the effect of passive ultrassonic irrigation (PUI) after preparation with the proposed groups in the accumulation of hard-tissue debris; and correlate the presence of hardtissue debris with smear layer evaluated by scanning eléctron microscope (SEM). Distal canals of thirty-eight lower molars were selected and divided in two groups: G1-TFA (n=19) and G2-RC (n=19). Each specimen was scanned three times: preand post-instrumentation of the root canal; and post-passive ultrassonic irrigation. After reconstruction of the scanned images, a co-registration was done with DataViewer. The softwares CTan and CTvol were used for binarization of the objects of interest, morphometrics alterations and reconstruction of tridimensional models and hard-tissue debris models. Volume increasing, non-prepared surfaces and hardtissue debris after instrumentation were measured. After final irrigation, the root canals were clived in halves at the apical third and analyzed by scanning eléctron microscope related to smear layer. The score system described by Hülsmann et al. (1997) was used. The results showed a non-parametric distribution by D'Agostino test. For that reason, Mann-Whitney test was used to compare the experimental groups and the Kruskall-Wallis test to compare intra-group performance. Dunn test determined which sample was different. Data shows that TF Adaptive removed more dentin in the whole root canal (p<0,05). There was no significant statistic difference comparing non-prepared surfaces between the systems (p>0,05). Related to hardtissue debris and reduction of hard-tissue debris after passive ultrassonic irrigation, there was no significant difference between TF Adaptive and Reciproc. The PUI reduced significantly hard-tissue debris, except for the apical third. The scanning electron microscope (SEM) showed a non-homogeneous smear layer covering the canal dentin walls, specially the Reciproc group. It was concluded that no system completely prepared the dentin walls of long-oval root canals and the passive ultrassonic irrigation decreased hard-tissue debris about 60-70% in the evaluated systems. SEM analysis reported no correlation between hard-tissue reduction and smear layer.