The Accuracy of a New Cone-beam Computed Tomographic Software in the Preoperative Working Length Determination Ex Vivo

Introduction

This study investigates the accuracy of 3D Endo software (Dentsply Sirona, Salzburg, Austria) to determine the working length when using preoperative cone-beam computed tomographic (CBCT) scans of extracted teeth, compared with conventional CBCT software and an electronic apex locator (EAL).

Comparison of the Accuracy of 3-dimensional Cone-beam Computed Tomography and Micro–Computed Tomography Reconstructions by Using Different Voxel Sizes

Introduction

Cone-beam computed tomography (CBCT) data are, in principle, metrically exact. However, clinicians need to consider the precision of measurements of dental morphology as well as other hard tissue structures. CBCT spatial resolution, and thus image reconstruction quality, is restricted by the acquisition voxel size. The aim of this study was to assess geometric discrepancies among 3-dimensional CBCT reconstructions relative to the micro-CT reference.

Methods

A total of 37 permanent teeth from 9 mandibles were scanned with CBCT 9500 and 9000 3D and micro-CT. After semiautomatic segmentation, reconstructions were obtained from CBCT acquisitions (voxel sizes 76, 200, and 300 μm) and from micro-CT (voxel size 41 μm). All reconstructions were positioned in the same plane by image registration. The topography of the geometric discrepancies was displayed by using a color map allowing the maximum differences to be located.

Results

The maximum differences were mainly found at the cervical margins and on the cusp tips or incisal edges. Geometric reconstruction discrepancies were significant at 300-μm resolution (P = .01, Wilcoxon test).

Conclusions

To study hard tissue morphology, CBCT acquisitions require voxel sizes smaller than 300 μm. This experimental study will have to be complemented by studies in vivo that consider the conditions of clinical practice.     

Detection of Various Anatomic Patterns of Root Canals in Mandibular Incisors Using Digital Periapical Radiography, 3 Cone-beam Computed Tomographic Scanners,and Micro–Computed Tomographic Imaging

Introduction

The purpose of this study was to compare the accuracy of digital periapical (PA) radiography and 3 cone-beam computed tomographic (CBCT) scanners in the identification of various internal anatomic patterns in mandibular incisors.

Methods

Forty mandibular incisors were scanned using micro–computed tomographic imaging as the gold standard to establish the internal anatomic pattern. The number of root canals and internal patterns were classified into type I (single canal, n = 12), type Ia (single oval canal, n = 12), and type III (2 canals, n = 16). The teeth were placed in a human mandible, and digital PA radiography and 3 CBCT scans (Kodak 9000 3D [Carestream Health, Rochester, NY], Veraviewepocs 3De [J Morita MFG Corp, Kyoto, Japan], NewTom 5G [QR Srl, Verona, Italy]) were performed. Two blinded examiners classified each tooth's anatomic pattern, which were then compared with the micro–computed tomographic determinations.

Results

Considering type I and type Ia, which both presented with 1 root canal, there was a high degree of accuracy for all methods used (P > .05). The same result was found for type III. When identifying the shape of single canals (type I), CBCT imaging was more accurate compared with PA radiography. Concerning oval canals (type Ia), there was a significant difference between PA radiography and NewTom CBCT (PA radiography = 44%, NewTom = 88%). However, there were no significant differences between the 3 CBCT units.

Conclusions

Double-exposure digital PA radiography for mandibular incisors is sufficient for the identification of the number of root canals. All CBCT devices showed improved accuracy in the identification of single root canal anatomy when a narrow canal was present. However, the identification of oval canals was improved only with the NewTom CBCT device.     

An Automated Measurement Method for the Endodontic Working Width of Lower Molars by Means of Parametric Models Using Cone-beam Computed Tomographcy and Micro–Computed Tomography

IntroductionA new method for the approximation of the root canal's cross-sectional shape and its working width using cone-beam computed tomographic (CBCT) or micro–computed tomographic (micro-CT) imaging was introduced.MethodsScanned data from 29 extracted human mandibular first and second molar distal root canals without instrumentation were reconstructed and analyzed with a self-developed measurement algorithm. The 3-dimensional volume models were sliced perpendicular to the vertical axis. Using different 2-dimensional parametric models, the contour of each root canal slice was approximated and used to determine the canal's cross-sectional dimensions. The measurements of minor width, major width, and the root canal's conicity were statistically analyzed using analysis of variance.ResultsThe measured minor and major widths of the investigated root canals were significantly higher (probability value P < .05) when evaluated by CBCT images than the results obtained from micro-CT data. Both dimensions increased starting from the apical foramen (P < .01). The narrowest measured canal widths were 0.19–0.24 mm for CBCT imaging and 0.09–0.21 mm for micro-CT imaging in the apical part. The maximum values for conicity were between 13% and 17% in the cervical third.ConclusionsThe 3-dimensional imaging data from CBCT and micro-CT imaging enabled a valuable anatomic assessment of the root canal's cross-sectional working width along the canal up to the physiological foramen in order to determine an adequate apical diameter as well as the correct measured taper in the cervical and medial part.     

Comparative Evaluation of Dentinal Microcrack Formation before and after Root Canal Preparation Using Rotary,Reciprocating, and Adaptive Instruments at Different Working Lengths—A Micro–computed Tomographic Study

IntroductionThis study aimed to compare root dentinal microcrack formation after root canal shaping using rotary, reciprocating, and adaptive instruments at different working lengths using micro–computed tomographic imaging.MethodsOne hundred eighty extracted mature mandibular molar mesial roots with 2 separate canals were selected. The mesial roots were resected at the cementoenamel junction and randomly divided into 4 groups (n = 45) based on the nickel-titanium file system used: ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Gold (Dentsply Maillefer), Twisted File Adaptive (SybronEndo, Orange, CA), and Reciproc Blue (VDW, Munich, Germany). Each of the 4 groups were then subdivided into 3 groups (n = 15) depending on the working length used for root canal preparation (ie, instrumentation 1 mm short, flush, and 1 mm beyond the major apical foramen). The roots were imaged with micro–computed tomographic scanning before and after root canal preparation. The cross-sectional images generated were screened to detect the presence of new microcracks.ResultsThe ProTaper Universal system significantly increased the number of postinstrumentation microcracks at all working lengths (P ≤ .05). No significant increase (P > .05) in postinstrumentation microcracks was observed in the ProTaper Gold, Twisted File Adaptive, or Reciproc Blue groups.ConclusionsRotary instrumentation induced a higher number of dentinal microcracks compared with reciprocating and adaptive instruments. Instrumentation at different working lengths did not significantly influence the formation of dentinal microcracks.