According to our findings and the results of the clinical trial, the occurrence of postoperative pain was low and similar between the reciprocating and rotary techniques during the time intervals assessed. These results are different from basic laboratory studies that affirm that the reciprocating techniques tend to promote more postoperative pain since extrusion of debris is greater.

The different glide path techniques promoted minimal apical transportation, and the reciprocating single-file system tested remained relatively centralized within the root canal. Also, the different techniques interfered in the cleaning effectiveness of the reciprocating system.

The purpose of this study was to evaluate, by scanning electron microscopy (SEM), smear layer removal and quantify, by atomic absorption spectrophotometry, the amount of calcium ion present in the chelating solutions after their use. Sixteen extracted canines were instrumented using the step-back technique and were assigned to 3 groups according to the irrigating solution used: G1: 1 mL 17% EDTAC between each file; G2: 1 mL 17% CDTA; G3: 1 mL 17% EGTA. The solutions were collected after use. The teeth were cleaved longitudinally, evaluated under SEM and assessed for smear layer by blinded examiners and scored from 1 to 4. In order to quantify calcium ion release, the collected solutions were examined by atomic absorption spectrophotometry. Freidman's test was used for statistical analysis of SEM values and showed that canals irrigated with 17% EDTAC and 17% CDTA had significantly less smear layer throughout the canals than 17% EGTA (p<0.01). For analysis of the collected solutions, Tukey's test was used and showed that EDTAC and CDTA had a greater amount of calcium ions (22.8+/-7.54 and 60.6+/-20.67 microg/mL, respectively) compared to EGTA (70.5+/-14.2 microg/mL) (p<0.01). The association both methodologies may contribute to the understanding of how these solutions act in the root canal.

The PBM reduces the prevalence of postoperative pain and may benefit patients who need endodontic treatment.

Objective:The complete filling material removal during endodontic retreatment is a clinical procedure difficult to achieve. The aim of this study was to evaluate the efficacy of reciprocating and continuous rotary nickel-titanium instruments used in root canal retreatment.Materials and Methods:Forty freshly extracted human premolars were cleaned and shaped by the crown-down technique, followed by filling by the lateral compaction technique. The teeth were randomly separated into two groups (n = 20), according to the system used for filling material removal: G1 - Reciproc and G2 - ProTaper Universal Retreatment System. The teeth were photographed under operating microscope at ×8 magnification; and the total area of the root canal and remaining filling material were quantified.Results:No statistically significant difference (P > 0.05) in residual filling material was observed between groups; however, the time required for filling removal was significantly shorter for Reciproc system (P < 0.05).Conclusions:It was observed remaining filling material in all teeth, irrespective of the system used; however, root canal retreatment was faster when reciprocating motion was used.

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Objective:To compare cleaning effectiveness by histological analysis of a reciprocating single-file system with ProTaper rotary instruments during the preparation of curved root canals in extracted teeth.Methods:A total of 40 root canals with curvatures ranging between 20 - 40 degrees were divided into two groups of 20 canals. Canals were prepared to the following apical sizes: Reciproc size 25 (n=20); ProTaper: F2 (n=20). The normal distribution of data was tested by the Kolmogorov-Smirnov test and the values obtained for the test (Mann-Whitney U test, P < .05) were statistically analyzed using the GraphPad InStat for the Mac OS software (GraphPad Software, La Jolla, CA, USA).Results:There were no significant differences in remaining debris (P > .05) between the two groups.Conclusion:The application of reciprocating motion during instrumentation did not result in increased debris when compared with continuous rotation motion, even in the apical part of curved canals. Both instruments resulted in debris in the canal lumen, irrespective of the movement kinematics applied.