Cyclic fatigue resistance, torsional resistance, and metallurgical characteristics of M3 Rotary and M3 Pro Gold NiTi files

Objectives: To evaluate the mechanical properties and metallurgical characteristics of the M3 Rotary and M3 Pro Gold files (United Dental). Materials and Methods: One hundred and sixty new M3 Rotary and M3 Pro Gold files (sizes 20/0.04 and 25/0.04) were used. Torque and angle of rotation at failure (n = 20) were measured according to ISO 3630-1. Cyclic fatigue resistance was tested by measuring the number of cycles to failure in an artificial stainless steel canal (60° angle of curvature and a 5-mm radius). The metallurgical characteristics were investigated by differential scanning calorimetry. Data were analyzed using analysis of variance and the Student-Newman-Keuls test. Results: Comparing the same size of the 2 different instruments, cyclic fatigue resistance was significantly higher in the M3 Pro Gold files than in the M3 Rotary files (p < 0.001). No significant difference was observed between the files in the maximum torque load, while a significantly higher angular rotation to fracture was observed for M3 Pro Gold (p < 0.05). In the DSC analysis, the M3 Pro Gold files showed one prominent peak on the heating curve and 2 prominent peaks on the cooling curve. In contrast, the M3 Rotary files showed 1 small peak on the heating curve and 1 small peak on the cooling curve. Conclusions: The M3 Pro Gold files showed greater flexibility and angular rotation than the M3 Rotary files, without decrement of their torque resistance. The superior flexibility of M3 Pro Gold files can be attributed to their martensite phase

Correction to: Respiratory health efects of e-cigarette substitution for tobacco cigarettes: a systematic review

Correction to: Harm Reduction Journal (2023) 20:1 https://doi.org/10.1186/s12954-023-00877-

Respiratory health effects of e-cigarette substitution for tobacco cigarettes: a systematic review

Background: E-cigarettes (electronic nicotine delivery system, ENDS) have been presented as a harm reduction strategy for people who smoke tobacco cigarettes but who cannot achieve abstinence, or for those who wish to continue to enjoy nicotine and the habit of smoking. What are the health effects of the substitution of ENDS for tobacco cigarettes? This systematic review evaluates the evidence of human clinical tests on the respiratory effects of ENDS use in participants who smoke tobacco cigarettes. Methods: A registered and published protocol was developed conforming to PRISMA 2020 and AMSTAR2 standards. The literature search was conducted in PubMed, Scopus, and the CENTRAL Cochrane Library and updated to May 2022. Three supplementary searches and a grey literature search were performed. Studies were evaluated with the JBI quality tools and the Oxford Catalogue of Bias. Due to the heterogeneity (diversity) of the studies, a narrative data synthesis was performed on the test findings plus three sub-group analyses. Results: The review consists of sixteen studies and twenty publications. Spirometry tests comprised the majority of the data. In total, 66 respiratory test measurements were reported, out of which 43 (65%) were not significant. Statistically significant findings were mixed, with 9 tests showing improvements and 14 measuring declines, none of which was clinically relevant. Ten studies were rated at a high risk of bias, and six had some concerns primarily due to inadequate research designs and the conduct of the studies. Reporting bias was documented in thirteen studies. Conclusions: Most of the studies showed no difference in respiratory parameters. This indicates that ENDS substitution for smoking likely does not result in additional harm to respiratory health. Due to the low quality of the studies, confidence in the conclusions is rated as low. Robust studies with a longer duration and sufficient power are required to validate any potential benefits or possible harms of ENDS substitution. Registration PROSPERO #CRD42021239094, International Registered Report Identifier (IRRID): DERR1-10.2196/29084

MMP-7 and MMP-9 Are Overexpressed in The Synovial Tissue from Severe Temporomandibular Joint Dysfunction

Matrix metalloproteinases (MMPs) are tissue-enzymes that play a key role during the remodeling process, such as in inflammatory diseases. MMP-7 and MMP-9 have been shown to be implicated in extracellular matrix homeostasis and in joint disc remodeling. The objective of this study was to determine the relation of MMP-7 and MMP-9 expression with severe temporomandibular joint dysfunction, in particular with anterior disk displacement without reduction (ADDwoR), using an immunohistochemical approach. Therefore, twenty human temporomandibular synovia in the test group and ten in the control group were collected. The results showed there was a statistically significant difference (P\u3c0.001) for morphometric and densitometric analysis of both detected MMPs in control and test groups. In conclusion, MMP-7 and MMP-9 were overexpressed in the synovial tissue of patients with ADDwoR

Root-end resection with or without retrograde obturation after orthograde filling with two techniques: A micro-CT study

To evaluate the filling ability of two orthograde obturation techniques followed by the apical resection with or without retrograde obturation through micro-computed tomography (CT). Thirty-two single-rooted permanent teeth were prepared and randomised into four groups (n = 8) according to the orthograde obturation technique (single cone technique [SCT] and mineral trioxide aggregate placement) combined or not with retrograde obturation. The volume of voids (VoV) within the entire endodontic space, the apical 3 mm, and 1 mm after root resection was calculated by micro-CT. Statistical analysis showed no significant difference among the groups regarding the total VoV in all root canals, as well as within the apical 1 mm after root resection. The SCT and apical resection without retrograde filling showed significantly better results in terms of VoV at the apical 3 mm after root resection. Within the study limitations, SCT associated with apical resection without retrograde preparation exhibited a similar or less amount of voids than the other groups

Shaping ability of Procodile and R6 Reziflow nickel-titanium reciprocating instruments in curved mesial root canals of mandibular molars: A MicroCT study

To compare the shaping ability of Procodileand R6 Reziflow instruments used in reciprocating motion in severely curved root canals, assessed with micro-computed tomography (mu CT). Fourteen extracted human mandibular first molars were randomly assigned to two instrumentation techniques (n = 14 mesial root canals): Procodile or R6 Reziflow. For both groups, root canals were prepared to the working length up to a size 25,.06 taper. Molars were virtually divided into apical, middle and coronal thirds and mu CT was used to scan all samples pre- and post-root canal. Canal transportation, centring ability, volume, surface area and unprepared area were evaluated. Geometrical parameter changes were compared with preoperative values (one-way analyses of variance and Tukey multiple comparison post-hoc test) between groups and Student t-test within groups (alpha = 0.05) Significantly less transportation was observed associated with the Procodile technique in the molar's coronal third compared to the R6 Reziflow technique (p &lt;.05). No significant differences in root canal centring ability, volume, surface area and unprepared area were observed. Procodile showed a lower percentage increase of surface area compared to R6 Reziflow (p &lt;.05). The Procodile and R6 Reziflow techniques applied to first molar root canal performed similarly except for the less transportation observed in the coronal third using Procodile.Research Highlights MicroCT analysis of canal geometry before and after instrumentation revealed that Procodile and R6 Reziflow showed a similar shaping ability to shape curved root canals without substantially modifications of the original tooth anatomy

Common, low-frequency, rare, and ultra-rare coding variants contribute to COVID-19 severity

The combined impact of common and rare exonic variants in COVID-19 host genetics is currently insufficiently understood. Here, common and rare variants from whole-exome sequencing data of about 4000 SARS-CoV-2-positive individuals were used to define an interpretable machine-learning model for predicting COVID-19 severity. First, variants were converted into separate sets of Boolean features, depending on the absence or the presence of variants in each gene. An ensemble of LASSO logistic regression models was used to identify the most informative Boolean features with respect to the genetic bases of severity. The Boolean features selected by these logistic models were combined into an Integrated PolyGenic Score that offers a synthetic and interpretable index for describing the contribution of host genetics in COVID-19 severity, as demonstrated through testing in several independent cohorts. Selected features belong to ultra-rare, rare, low-frequency, and common variants, including those in linkage disequilibrium with known GWAS loci. Noteworthily, around one quarter of the selected genes are sex-specific. Pathway analysis of the selected genes associated with COVID-19 severity reflected the multi-organ nature of the disease. The proposed model might provide useful information for developing diagnostics and therapeutics, while also being able to guide bedside disease management. © 2021, The Author(s)

Identifying spin bias of nonsignificant findings in biomedical studies

Abstract Objective The purpose of this research note is to share a technique for the identification of spin bias that we developed as part of a living systematic review on the cardiovascular testing of e-cigarette substitution for cigarette smoking. While some researchers have remarked on the subjective nature of ascertaining spin bias, our technique objectively documents forms of spin bias arising from the misrepresentation of nonsignificant findings and from the omission of data. Results We offer a two-step process for the identification of spin bias consisting of tracking data and findings and recording of data discrepancies by describing how the spin bias was produced in the text. In this research note, we give an example of the documentation of spin bias from our systematic review. Our experience was that nonsignificant results were presented as causal or even as significant in the Discussion of studies. Spin bias distorts scientific research and misleads readers; therefore it behooves peer reviewers and journal editors to make the effort to detect and correct it

A scoping review of new technologies for dental plaque quantitation: Benefits and limitations

&lt;h3&gt;Objectives&lt;/h3&gt;&lt;p&gt;To determine the validity and reliability of novel digitalized tools for &lt;a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/tooth-plaque"&gt;dental plaque&lt;/a&gt; detection and explore the benefits and limitations connected to their use.&lt;/p&gt;&lt;h3&gt;Data&lt;/h3&gt;&lt;p&gt;Reporting followed the Preferred Reporting Items for &lt;a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/systematic-review"&gt;Systematic Reviews&lt;/a&gt; and Meta-Analyses (PRISMA) Extension for Scoping Reviews. All human clinical studies comparing dental plaque detection using digitalized systems against a standard reference were included.&lt;/p&gt;&lt;h3&gt;Sources&lt;/h3&gt;&lt;p&gt;PubMed and Scopus were screened from 01 January 2013 to 28 September 2023. Bibliographies of primary studies and principal peer-reviewed scientific journals were manually searched.&lt;/p&gt;&lt;h3&gt;Study selection&lt;/h3&gt;&lt;p&gt;The initial search identified 576 articles, with a total of 13 included in the review, published between 2015 and 2023. Most of the studies included (77&nbsp;%) were cross-sectional with three being prospective. Digital devices captured 2D and 3D images via cameras and intra-oral scanners, respectively. The Turesky's modified &lt;a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/plaque-index"&gt;plaque index&lt;/a&gt; was the most frequent clinical index. Correlation with clinical examination was moderate to strong, with good to excellent intra- and inter-system agreement.&lt;/p&gt;&lt;h3&gt;Conclusions&lt;/h3&gt;&lt;p&gt;Within the limitations of this scoping review, image analysis-based plaque detection systems demonstrated good correlations with clinical plaque indices, using both 2D and &lt;a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/3d-imaging"&gt;3D imaging&lt;/a&gt; systems. Whilst digital plaque detection devices offer advantages in terms of procedural standardization and reproducibility, they also have limitations, therefore currently, their application should be underpinned by a comprehensive clinical examination.&lt;/p&gt;&lt;h3&gt;Clinical significance&lt;/h3&gt;&lt;p&gt;Digital plaque detection tools, that provide standardized measurements and store acquired images, facilitate more informed feedback to patients. This objective analysis may enhance clinician confidence in their utility for &lt;a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/clinical-trial"&gt;clinical trials&lt;/a&gt; and other applications.&lt;/p&gt;&lt;h2&gt;Funding&lt;/h2&gt;&lt;p&gt;This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.&lt;/p&gt

Evaluation of the Cyclic Fatigue of Two Single Files at Body and Room Temperature with Different Radii of Curvature

Background: To compare the influence of different temperatures and curvature radii on the cyclic fatigue resistance of F6 SkyTaper (F6ST) and One Curve (OC) single file nickel-titanium rotary instruments. Methods: A total of 120 instruments of F6ST and OC #25.06 were evaluated in 5 mm and 3 mm curvature radii at two temperatures (20 °C ± 1 °C and 37 °C ± 1 °C) in 16 mm stainless steel artificial canals associated with a curvature of 60°. The cyclic fatigue of tested files was assessed by employing a customized testing apparatus and expressed as times to fracture (TtF). A statistical analysis was performed with the significance level set at 95%. Results: All instruments decreased their TtF at 37 °C except for OC in the 3 mm radius, in which no significant difference was detected between 20 °C and 37 °C. A 3 mm curvature radius negatively affected TtF of all tested instruments, except for F6ST at 20 °C. F6ST had higher TtF than OC in the 3 mm radius at 20 °C, with no significant difference between them in the other tested conditions. Conclusions: Under the limits of the present in vitro study, body temperature impaired cyclic fatigue resistance of all files, except for OC in the 3 mm curvature radius. All instruments exhibited lower times to fracture in the 3 mm radius, excluding F6ST at 20 °C