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A growing body of research supports an association between periapical inflammation and an increased risk of developing systemic diseases. There is currently no scientific evidence to support a causal effect of inflammation on the onset of insulin resistance (IR) in patients with apical periodontitis (AP). The aim of this in vitro study was to evaluate any association between AP and levels of serum inflammatory factors potentially associated with the onset of IR, and to investigate the effect of root canal treatment (RCT) on these systemic inflammation markers and on the response in vitro to insulin. A total of 27 control subjects and 27 patients with AP were enrolled. Patients with AP underwent RCT and were followed-up 6 and 12 months post-treatment. Enzyme-linked immunosorbent assays were used to evaluate serum levels of proinflammatory cytokines interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor (TNF)-α. The response in vitro to insulin was assessed by measuring glucose consumption in a human pancreatic epithelioid carcinoma cell line treated with sera from healthy and AP subjects. At baseline AP was associated with significant higher levels of IL-1, IL-6, and IL-8 in the serum of untreated (AP) patients vs controls (P <.001). Glucose consumption decreased in pancreatic cells incubated with baseline serum from patients with AP, in a manner proportional to total cytokines amount. Notably, endodontic treatment was associated with reduced levels of cytokines (P <.001) and improved response to insulin in AP group (P <.001). Our findings suggest that AP may promote inflammatory-driven IR in an in vitro model, and that RCT may ameliorate inflammatory mediators in vivo and the cellular response to insulin in vitro. [ABSTRACT FROM AUTHOR]

Cardiovascular diseases are the leading cause of mortality worldwide. Apical periodontitis (AP) has been associated with an increased risk of cardiovascular diseases. A correlation has been shown between chronic AP and endothelial dysfunction (ED), but there is no evidence to indicate ED improves after endodontic treatment in patients with periapical lesions. The aim of this study was to investigate vascular and molecular markers of early ED before and after root canal treatment in young adults with chronic AP. Twenty control subjects and 21 patients with AP were assessed at baseline. The AP patients were also evaluated 2 and 12 months post-treatment. Endothelial flow reserve was assessed via an endothelial function test, and enzyme-linked immunosorbent assays were used to evaluate plasma levels of proinflammatory cytokines interleukin (IL)-1, IL-6, and tumor necrosis factor alpha; vasoconstrictor ED marker endothelin (ET)-1; circulating endothelial adhesion markers intercellular adhesion molecule 1 (ICAM-1)/CD54 and soluble vascular cellular adhesion molecule (sVCAM)-1/CD106; soluble CD14; and the endothelial leukocyte adhesion molecule (E-selectin). AP was associated with increased serum levels of ET-1, ICAM-1, E-selectin, IL-1, and sCD14, suggesting early vascular ED, with no macroscopic evidence of a reduction in endothelial flow reserve. Root canal treatment ameliorated inflammation and early ED, lowering plasma levels of IL-1, sCD14, ET-1, ICAM-1/CD54, and E-selectin to those of control subjects. Our findings suggest that AP may drive early vascular ED and that the endodontic therapy of AP ameliorates early ED. • Apical periodontitis (AP) was associated with increased serum levels of endothelin 1, intercellular adhesion molecule 1, E-selectin, interleukin 1, and soluble CD14. • Plasma levels of interleukin 1, soluble CD14, endothelin 1, intercellular adhesion molecule 1, and E-selectin in patients with AP returned to those of healthy subjects after endodontic treatment. • Root canal treatment ameliorated inflammation and early endothelial dysfunction. [ABSTRACT FROM AUTHOR]

Introduction Contracted endodontic cavities (CECs) have developed from the concept of minimally invasive dentistry and provide an alternative to traditional endodontic cavities (TECs). They have been designed in an effort to preserve the mechanical stability of teeth. The contracted cavity design preserves more of the dentin but may influence the geometric shaping parameters. The aim of this micro–computed tomographic study was to evaluate the influence of contracted endodontic cavities on the preservation of the original root canal anatomy after shaping with nickel-titanium rotary instruments. Methods Thirty extracted human mandibular molars with fully formed apices and independent mesial canals were randomly assigned to group 1 (TEC) and group 2 (CEC). Each group was shaped using ProGlider (Dentsply Maillefer, Ballaigues, Switzerland) and WaveOne Gold (Dentsply Maillefer). Irrigation was performed with 10% EDTA and 5% sodium hypochlorite. Samples were scanned before and after canal shaping to match canal volumes (SkyScan; Bruker microCT, Kontich, Belgium [100 kV, 100 μA, and 15-μm resolution]), and images were analyzed to evaluate canal volumes, surface areas, and centroid shift on cross sections at −1 mm and −3 mm from the apex. Results TECs showed a greater preservation of the original root canal anatomy with less apical transportation than CECs, possibly because of the absence of coronal interferences and, therefore, fewer pecking motions required to complete instrumentation. Conclusions Within the limitations of this study, TECs may lead to a better preservation of the original canal anatomy during shaping compared with CECs, particularly at the apical level. [ABSTRACT FROM AUTHOR]

Introduction: A coronal seal is fundamental for a positive outcome to endodontic therapy. In this in vitro study, we evaluated the adaptation of composite resins in postendodontic restorations using optical coherence tomographic (OCT) imaging. Our null hypothesis was that there would be no difference in marginal adaptation to the pulp chamber floor between resin composites of different viscosities. Methods: Thirty intact upper molars extracted for periodontal reasons were selected, endodontically treated, and filled with gutta-percha. The excess gutta-percha was entirely removed from the pulp chamber floor, and teeth were randomly divided into 3 groups (n = 10) according to the material used for the restoration: group 1: 0.5-mm horizontal layer of flowable composite followed by nanohybrid composite, group 2: bulk layering of bulk fill flowable composite; and group 3: oblique layering of nanohybrid composite. The degree of adaptation to the cavity floor was assessed using OCT imaging, and images were analyzed with the software program ImageJ (National Institutes of Health, Bethesda, MD) to assess the marginal gap between the composite and the pulp chamber floor. Collected data were statistically analyzed using analysis of variance testing, and statistical significance was set at P < .05. Results: Flowable composites showed significantly better adaptation than traditional packable nanohybrid composites (P < .05). All significant differences were found between groups 1 and 2. Conclusions: Within the limitations of this OCT imaging-based in vitro study, it was concluded that the flowable composite (flow + nanofilled; flow bulk fill composite) adapted better to the pulp chamber floor than the packable nanohybrid composite resin. Further studies are necessary to confirm these results. [ABSTRACT FROM AUTHOR]

Introduction The finite element method (FEM) has been proposed as a method to analyze stress distribution in nickel-titanium (NiTi) rotary instruments but has not been assessed as a method of predicting the number of cycles to failure (NCF). The objective of this study was to predict NCF and failure location of NiTi rotary instruments by FEM virtual simulation of an experimental nonstatic fatigue test. Methods ProTaper Next (PTN) X1, X2, and X3 files (Dentsply Maillefer, Baillagues, Switzerland) ( n = 20 each) were tested to failure using a customized fatigue testing device. The device and file geometries were replicated with computer-aided design software. Computer-aided design geometries (geometric model) were imported and discretized (numeric model). The typical material model of an M-Wire alloy was applied. The numeric model of the device and file geometries were exported for finite element analysis (FEA). Multiaxial random fatigue methodology was used to analyze stress history and predict instrument life. Experimental data from PTN X2 and X3 were used for virtual model tuning through a reverse engineering approach to optimize material mechanical properties. Tuned material parameters were used to predict the average NCF and failure locations of PTN X1 by FEA; t tests were used to compare FEA and experimental findings ( P < .05). Results Experimental NCF and failure locations did not differ from those predicted with FEA ( P = .098). Conclusions File NCF and failure location may be predicted by FEA. Virtual design, testing, and analysis of file geometries could save considerable time and resources during instrument development. [ABSTRACT FROM AUTHOR]

Introduction The aim of this micro–computed tomography study was to describe the shaping properties of ProGlider/ProTaper Next (PG/PTN) and ScoutRace/BioRace (SR/BR) nickel-titanium rotary systems. Methods Thirty maxillary first permanent molars were selected. Mesiobuccal canals were randomly assigned ( n = 15) to PG/PTN or SR/BR groups. Irrigation was performed with 5% NaOCl and 10% EDTA. Specimens were scanned (voxel size, 9.1 μm) for matching volumes and surface areas and post-treatment analyses. Root canal centering ability, canal geometry enlargement, and thickness of dentinal wall at inner curvature were assessed at apical level and point of maximum curvature. Results were analyzed with 4 one-way analyses of variance. Results Canal centering ability was superior in PG/PTN ( P = .006 at apical level, P = .025 at point of maximum curvature). PG/PTN demonstrated a more conservative increase of canal areas ( P = .027 at apical level, P = .038 at point of maximum curvature). Centrifugal increase in canal diameters did not significantly differ between groups ( P = .65 at apical level, P = .61 at point of maximum curvature). Inner dentinal wall thickness was less reduced with PG/PTN compared with SR/BR, with no statistical differences ( P = .23 at point of maximum curvature, P = .89 at apical level). PG/PTN shaping taper ranged between 6% and 7%. Conclusions Neither system produced significant shaping errors in curved canals. PG/PTN system showed better preservation of canal anatomy. PTN offset section did not influence final preparation taper. [ABSTRACT FROM AUTHOR]

Introduction Instrument failure caused by excessive torsional stress can be controlled by creating a manual or mechanical glide path. The ProGlider single-file system (Dentsply Maillefer, Ballaigues, Switzerland) was recently introduced to perform a mechanical glide path. This study was designed to compare the effect of a glide path performed with PathFiles (Dentsply Maillefer) and ProGlider on torque, time, and pecking motion required for ProTaper Next X1 (Dentsply Maillefer) to reach the full working length in simulated root canals. Methods Forty Endo Training Blocks (Dentsply Maillefer) were used. Twenty were prepared with a mechanical glide path using PathFiles 1 and 2 (the PathFile group), and 20 were prepared with a mechanical glide path using a ProGlider single file (the ProGlider group). All samples were shaped with ProTaper Next X1 driven by an endodontic motor connected to a digital wattmeter. The required torque for root canal instrumentation was analyzed by evaluating the electrical power consumption of the endodontic engine. Electric power consumption (mW/h), elapsed time (seconds), and number of pecking motions required to reach the full working length with ProTaper Next X1 were calculated. Differences among groups were analyzed with the parametric Student t test for independent data ( P < .05). Results Elapsed time and electric power consumption were significantly different between groups ( P = .0001 for both). ProGlider appears to perform more efficiently than PathFiles in decreasing electric power consumption of ProTaper Next X1 to reach the full working length. Conclusions This study confirmed the ability of ProGlider to reduce stress in ProTaper Next X1 during shaping through a glide path and preliminary middle and coronal preflaring. [ABSTRACT FROM AUTHOR]

To evaluate shear stress (SS) and normal pressure (NP) at the tooth-restoration interface of highly-filled flowable resin composite applied to deep margin elevation technique through FEM analysis generated by a microCT scan. A reference maxillary molar with two class II cavities was prepared according to deep margin elevation protocol. A geometrical model was segmented from a micro-CT scan generating separate volumes of enamel, dentin and restorative materials. The 3D Finite Element (FE) model was subsequently built-up and an axial chewing load was simulated. Data concerning the tooth-restoration interface were analyzed in terms of SS and NP. Different materials and techniques were tested in order to evaluate the effects of the restorative material, the usage of a highly-filled flowable composite as liner and the substrate of the cervical area. Both SS and NP presented similar distribution, but showed significant differences between tested materials. Composites showed more homogeneous behavior in stress distribution compared to ceramic. The use of a highly-filled flowable composite as liner on the cervical margin significantly reduced SS and NP on the cavity floor and the cervical margin area. Lastly, stress distribution in the cavity floor area varied according to the cervical margin substrate: enamel showed a protective role in stress distribution. Highly-filled flowable resin composites showed encouraging results when applied to deep margin elevation from an interfacial mechanical point of view. Further studies are needed to validate these data and to better define the role of cervical enamel in stress distribution. • Micro-CT can be used to create a realistic finite element model of the tooth-restoration complex. • Highly-filled flowable resin reduced shear and normal pressure stresses on the cavity floor. • Shear and normal pressure stresses presented similar distributions, being influenced by the different materials. • Resin-based materials showed a more homogeneous behavior in stress distribution compared to ceramic. [ABSTRACT FROM AUTHOR]