Assessing apical transportation in curved canals: Comparison between cross-sections and micro-computed tomography

Department of Esthetic Dentistry, School of Dentistry, University of São Paulo, Brazil.
Brazilian oral research (Impact Factor: 0.94). 06/2012; 26(3):222-7. DOI: 10.1590/S1806-83242012000300007
Source: PubMed


The aim of this study was to compare two methods of assessing apical transportation in curved canals after rotary instrumentation, namely, cross-sections and micro-computed tomography (µCT). Thirty mandibular molars were divided into two groups and prepared according to the requirements of each method. In G1 (cross-sections), teeth were embedded in resin blocks and sectioned at 2.0, 3.5, and 5.0 mm from the anatomic apex. Pre- and postoperative sections were photographed and analyzed. In G2 (µCT), teeth were embedded in a rubber-base impression material and scanned before and after instrumentation. Mesiobuccal canals were instrumented with the Twisted File (TF) system (SybronEndo, Orange, USA), and mesiolingual canals, with the EndoSequence (ES) system (Brasseler, Savannah, USA). Images were reconstructed, and sections corresponding to distances 2.0, 3.5, and 5.0 mm from the anatomic apex were selected for comparison. Data were analyzed using Mann-Whitney's test at a 5% significance level. The TF and ES instruments produced little deviation from the root canal center, with no statistical difference between them (P > 0.05). The canal transportation results were significantly lower (0.056 mm) in G2 than in G1 (0.089 mm) (p = 0.0012). The µCT method was superior to the cross-section method, especially in view of its ability to preserve specimens and provide results that are more closely related to clinical situations.

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    • "Apical root canal transportation was evaluated through various image methods, such as radiographs5,8,15,26,27, cone-beam computed tomography (CBCT)12,18 and micro-computed tomography (micro-CT)7,9,28,29. Although CBCT and micro-CT images allow a 3-dimensional evaluation of the root canal before and after preparation, standardized radiographs are a more accessible method, by which curvature changes are verified by comparison of the pre- and postoperative images5,8,26,27. "
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    ABSTRACT: Objective: This study evaluated apical transportation associated with ProTaper Universal Fl, F2 and F3 rotary files in curved canais prepared by undergraduate students. Material and methods: Twenty mesial roots of mandibular molars with curvatures ranging between 25° and 35° were selected. Mesiobuccal canals were instrumented by twenty students with the ProTaper system (Dentsply-Maillefer, Ballaigues, Switzerland) according to the manufacturer's instructions. Pre-fiaring was performed with Sl and SX files. A #15 K-file was inserted into the root canal up to the working length (WL), and an initial digital radiograph was taken in a buccolingual direction (baseline). Afterwards, the S1, S2, F1, F2, and F3 files were employed up to the WL. Other radiographies were taken in the same orientation of the baseline after the use of the Fl, F2, and F3 files, with each file inserted into the root canal. The radiographic images were overlapped, and the Image J software was used to measure the distance between the rotary files' ends and the #15 K-file's end, characterizing the apical transportation. Data were analyzed by Repeated Measure ANOVA and by the SNK post hoc test (P<0.05). Results: It was verified that file size affected apical transportation significantly (P<0.001). The F3 file showed higher apical transportation than Fl and F2, while between these last files there was no difference. Conclusion: The undergraduate students produced lower apical transportation in curved canals when they did not use the F3 rotary file.
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    ABSTRACT: Proper chemomechanical disinfection of the entire root canal system is required for a successful treatment outcome. Various techniques of mechanical root canal preparation have been introduced and described. Preservation of the integrity of the root canal anatomy and especially of the location of the apical foramen is important during mechanical root canal preparation. Despite the introduction of flexible nickel–titanium instruments and torque-limited devices, root canal preparation of severely curved canals is still challenging and canals may be transported and/or other procedural errors may occur during preparation procedures. There are several aspects that influence the performance of root canal instruments with respect to their shaping ability. This article elucidates different parameters having an impact on canal transportation and discusses the impact of canal transportation on treatment outcomes.
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    ABSTRACT: Introduction: The aim of this study was to evaluate whether rotary instrumentation using saline, EDTA 17% solution, or RC-Prep (Premier Dental, Philadelphia, PA) resulted in differences in root canal transportation. The secondary objective was to assess if instrumentation using these agents caused changes in the working length and canal volume. Methods: Moderately curved mesiobuccal roots of 24 maxillary molars were standardized in length and randomized into 1 control and 2 experimental groups. The canals were instrumented with 0.04 taper rotary files to size #30. All groups were irrigated with saline. Group 1 was also irrigated using EDTA 17% solution (Pulpdent Corp, Watertown, MA), and in group 2, RC-Prep was used. X-ray micro-computed tomographic scans and working length measurements were made before and after instrumentation. Three-dimensional models were created from the pre- and postinstrumentation scan data and compared for volume changes. Centroid points were calculated in cross-sectional slices of the canals, and transportation was determined by measuring the distance between the pre- and postinstrumentation points. The data were analyzed with 1-way analysis of variance (α = 0.05) and the Tukey post hoc test. Results: Less transportation was observed in group 2 than in group 1 (P = .001) and the control group (P = .014). Transportation in group 1 and the control group was not significantly different. Canal volume in group 1 was increased relative to group 2 (P = .004) and the control group (P = .022). No significant differences in the working length were observed. Conclusions: The use of chelating agents during root canal instrumentation did not significantly increase apical transportation.
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