Micro-CT assessment of the shaping ability of four root canal instrumentation systems in oval-shaped canals.

AIM: To compare the shaping ability of four root canal instrumentation systems in oval-shaped canals using micro-computed tomographic analysis. METHODOLOGY: Forty anatomically matched mandibular incisors were scanned and assigned to four groups (n = 10), according to the canal preparation protocol: BioRace, Reciproc, Self-Adjusting File (SAF) and TRUShape systems. After canal instrumentation, the specimens were rescanned, and the registered pre- and postoperative datasets were examined to evaluate the percentages of accumulated hard-tissue debris, untouched canal walls and dentine removed. Kruskal-Wallis and Mann-Whitney U-tests with Bonferroni correction were used to compare the variables in the groups (α = 5%). RESULTS: The preparation techniques did not affect the percentage of accumulated hard-tissue debris (P = 0.126). The percentage of untouched canal areas was significantly higher for BioRace (32.38%)compared to Reciproc (18.95%) and SAF (16.08%) systems (P < 0.05). Reciproc removed significantly more dentine (4.18%) than BioRace (2.21%) and SAF (2.56%) (P < 0.05). The TRUShape system had intermediate results for both untouched canal walls (19.20%) and dentine removed (3.77%), with no significant difference compared to BioRace, Reciproc and SAF systems. CONCLUSIONS: The preparation techniques resulted in the same level of accumulated hard-tissue debris. Compared to the other tested systems, BioRace was associated with more untouched canal walls and Reciproc produced the greatest amount of removed dentine. Although it touched more of the root canal walls, the SAF system removed less dentine, whereas TRUShape had intermediate results for these same parameters. None of the systems tested were able to provide optimal shaping ability in oval-shaped canals.

A quality assessment of randomized controlled trial reports in endodontics.

AIM: To assess the quality of the randomized clinical trial (RCT) reports published in Endodontics between 1997 and 2012. METHODOLOGY: Retrieval of RCTs in Endodontics was based on a search of the Thomson Reuters Web of Science (WoS) database (March 2013). Quality evaluation was performed using a checklist based on the Jadad criteria, CONSORT (Consolidated Standards of Reporting Trials) statement and SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials). Descriptive statistics were used for frequency distribution of data. Student's t-test and Welch test were used to identify the influence of certain trial characteristics upon report quality (α = 0.05). RESULTS: A total of 89 RCTs were evaluated, and several methodological flaws were found: only 45% had random sequence generation at low risk of bias, 75% did not provide information on allocation concealment, and 19% were nonblinded designs. Regarding statistics, only 55% of the RCTs performed adequate sample size estimations, only 16% presented confidence intervals, and 25% did not provide the exact P-value. Also, 2% of the articles used no statistical tests, and in 87% of the RCTs, the information provided was insufficient to determine whether the statistical methodology applied was appropriate or not. Significantly higher scores were observed for multicentre trials (P = 0.023), RCTs signed by more than 5 authors (P = 0.03), articles belonging to journals ranked above the JCR median (P = 0.03), and articles complying with the CONSORT guidelines (P = 0.000). CONCLUSIONS: The quality of RCT reports in key areas for internal validity of the study was poor. Several measures, such as compliance with the CONSORT guidelines, are important in order to raise the quality of RCTs in Endodontics.

Micro-CT assessment of dentinal micro-cracks after root canal filling procedures.

AIM: To evaluate the frequency of dentinal micro-cracks after root canal filling procedures with GuttaCore (GC), cold lateral compaction (CLC) and warm vertical compaction (WVC) techniques in mandibular molars using micro-computed tomographic analysis. METHODOLOGY: Thirty mesial roots of mandibular molars, with a type II Vertucci's canal configuration, were prepared to working length with a Reciproc R40 instrument and randomly assigned to one of the three experimental groups (n = 10), according to the technique used for root filling: GC, CLC or WVC. The GC group was filled with a size 40 GC obturator, whilst CLC and WVC groups used conventional gutta-percha cones. AH Plus sealer was used in all groups. The specimens were scanned at an isotropic resolution of 14.25 µm before and after root canal preparation and after root filling. Then, all pre- and postoperative cross-sectional images of the roots (n = 41 660) were screened to identify the presence of dentinal defects. RESULTS: Overall, 30.75% (n = 12 810) of the pre- + post-filling images displayed dentinal defects. In the GC, CLC and WVC groups, dentinal micro-cracks were observed in 18.68% (n = 2510), 15.99% (n = 2389) and 11.34% (n = 1506) of the cross-sectional images, respectively. All micro-cracks identified in the post-filling scans were also observed in the corresponding post-preparation images. CONCLUSION: Root fillings in all techniques did not induce the development of new dentinal micro-cracks.

Computed radiography simulation using the Monte Carlo code MCNPX.

Simulating X-ray images has been of great interest in recent years as it makes possible an analysis of how X-ray images are affected owing to relevant operating parameters. In this paper, a procedure for simulating computed radiographic images using the Monte Carlo code MCNPX is proposed. The sensitivity curve of the BaFBr image plate detector as well as the characteristic noise of a 16-bit computed radiography system were considered during the methodology's development. The results obtained confirm that the proposed procedure for simulating computed radiographic images is satisfactory, as it allows obtaining results comparable with experimental data.

Assessment of weld thickness loss in offshore pipelines using computed radiography and computational modeling.

In order to guarantee the structural integrity of oil plants it is crucial to monitor the amount of weld thickness loss in offshore pipelines. However, in spite of its relevance, this parameter is very difficult to determine, due to both the large diameter of most pipes and the complexity of the multi-variable system involved. In this study, a computational modeling based on Monte Carlo MCNPX code is combined with computed radiography to estimate the weld thickness loss in large-diameter offshore pipelines. Results show that computational modeling is a powerful tool to estimate intensity variations in radiographic images generated by weld thickness variations, and it can be combined with computed radiography to assess weld thickness loss in offshore and subsea pipelines.

Methodology for digital radiography simulation using the Monte Carlo code MCNPX for industrial applications.

This work presents a methodology for digital radiography simulation for industrial applications using the MCNPX radiography tally. In order to perform the simulation, the energy-dependent response of a BaFBr imaging plate detector was modeled and introduced in the MCNPX radiography tally input. In addition, a post-processing program was used to convert the MCNPX radiography tally output into 16-bit digital images. Simulated and experimental images of a steel pipe containing corrosion alveoli and stress corrosion cracking were compared, and the results showed good agreement between both images.

Dose-image quality study in digital chest radiography using Monte Carlo simulation.

One of the main preoccupations of diagnostic radiology is to guarantee a good image-sparing dose to the patient. In the present study, Monte Carlo simulations, with MCNPX code, coupled with an adult voxel female model (FAX) were performed to investigate how image quality and dose in digital chest radiography vary with tube voltage (80-150 kV) using air-gap technique and a computed radiography system. Calculated quantities were normalized to a fixed value of entrance skin exposure (ESE) of 0.0136 R. The results of the present analysis show that the image quality for chest radiography with imaging plate is improved and the dose reduced at lower tube voltage.