Effect of decontamination and cleaning on the shear bond strength of high translucency zirconia

(1) Background: This study evaluated the bonding performance of high translucency zirconia after diverse surficial decontamination and cleaning procedures. (2) Methods: High translucency zirconia (LavaTM Esthetic) specimens (2.0 mm × 20 mm × 10 mm) were exposed to different surface treatments prior to bonding to CoCr cylinders (d = 5 mm, height = 3 mm). All surfaces were sandblasted (40 µm aluminum oxide, 2 bar) and treated with alcohol (al), saliva (s), saliva + water (sw), or saliva + NaOCl + water (sn) before bonding was performed with the following adhesive luting systems: RelyXTM Unicem 2 (RX), ScotchbondTM Universal (SBU) + RelyXTM Ultimate (RU) or Monobond Plus (MP) + Multilink® Automix (ML). After 24 h, thermocycling (TC:12,000 × 5 °C/55 °C) and 90 days of storage at 37 °C in distilled water, the shear bond strength (SBS) was evaluated according to ISO/TS 11,405:2015. Failure modes along bonding areas were characterized. Means and standard deviations (n = 10 per group) were determined and statistically analyzed with one-way ANOVA/Bonferroni (α = 0.05). (3) Results: The SBS after 24 h varied between 3.5 (sRX) and 69.4 MPa (snMP + ML). Values from 0 (sRX) to 70.3 MPa (swRX) were found after TC. Data after 90 days of storage showed the lowest values for sRX (0 MPa) and the highest values for alSBU + RU (75.5 MPa). Adhesive failure was noted at all aging conditions. (4) Conclusions: SBU + RU or RX and MP + ML including saliva decontamination of the ceramic surface with water or NaOCl + water allow efficient bonding to LavaTM Esthetic

Antonym adjective pairs and prosodic iconicity: evidence from letter replications in an English blogger corpus

This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.While the general assumption has long been that natural languages exhibit an arbitrary pairing of form and meaning, there is increasing empirical evidence that iconicity in language is not uncommon. One example from spoken language involves iconic prosodic modulation, i.e. the changing of prosodic features such as duration and fundamental frequency to express meanings such as size and speed. In this paper, we use data from an English social media corpus, with 140 million words written by 19,320 bloggers, to investigate a counterpart to iconic prosodic modulation in written language, namely letter replications (e.g. loooong). We examine pairs of gradable adjectives such as short/long, tiny/huge and fast/slow, finding a higher frequency of letter replications for adjectives associated with greater size or spatial/temporal extent. We did not find an iconic effect on the number of replicated letters. Our results show evidence for iconic prosody in written language, and further demonstrate that social media databases offer an excellent opportunity to investigate naturalistic written language.Peer Reviewe

Toll-like Receptors, LPS, and Dental Monomers

Unreacted monomers released from dental resin-based composites at non-cytotoxic concentrations cause a depletion of glutathione and an increase of reactive oxygen species (ROS), leading to, e.g., DNA damage and apoptosis. ROS-sensitive MAP-kinases are activated by HEMA and TEGDMA. MAP-kinases are also involved in the bacteria-triggered cell responses of the innate immune system, e.g., after bacterial lipopolysaccharide (LPS) binding to the Toll-like receptor (TLR) 4. Therefore, both bacteria and monomers imply environmental stress to pulp tissue, and they may influence the target cell reactions in a combined way. In macrophages, cell-surface antigens and cytokines were up-regulated after exposure to LPS, but TEGDMA caused a significant downregulation. Regulation was dependent on exposure time, indicating that LPS and TEGDMA act differently on MAP-kinases. Furthermore, the cell type played a decisive role. Inhibition of the immune response may result in a decrease in inflammatory symptoms and/or a reduced defense capacity against bacteria

Register: Language Users’ Knowledge of Situational-Functional Variation

The Collaborative Research Center 1412 “Register: Language Users’ Knowledge of Situational-Functional Variation” (CRC 1412) investigates the role of register in language, focusing in particular on what constitutes a language user’s register knowledge and which situational-functional factors determine a user’s choices. The following paper is an extract from the frame text of the proposal for the CRC 1412, which was submitted to the Deutsche Forschungsgemeinschaft in 2019, followed by a successful onsite evaluation that took place in 2019. The CRC 1412 then started its work on January 1, 2020. The theoretical part of the frame text gives an extensive overview of the theoretical and empirical perspectives on register knowledge from the viewpoint of 2019. Due to the high collaborative effort of all PIs involved, the frame text is unique in its scope on register research, encompassing register-relevant aspects from variationist approaches, psycholinguistics, grammatical theory, acquisition theory, historical linguistics, phonology, phonetics, typology, corpus linguistics, and computational linguistics, as well as qualitative and quantitative modeling. Although our positions and hypotheses since its submission have developed further, the frame text is still a vital resource as a compilation of state-of-the-art register research and a documentation of the start of the CRC 1412. The theoretical part without administrative components therefore presents an ideal starter publication to kick off the CRC’s publication series REALIS. For an overview of the projects and more information on the CRC, see https://sfb1412.hu-berlin.de/

In-vitro performance of CAD/CAM crowns with insufficient preparation design

Purpose: To compare the debonding and fracture force of different CAD/CAM composite crowns with respect to the influence of water storage (Od vs. 90d/37 degrees C) and types of cementation (adhesive vs. self-adhesive). Methods: Extracted human molars were prepared with a worst-case preparation scenario providing a non retentive design (height similar to 4 mm; angle similar to 15 degrees) and reduced fitting (250 gm). After digitalization, 72 crowns (n = 8 per group; circular wall thickness 1.5 mm/occlusal thickness similar to 2.5 mm) were milled from the composites (CS, LU), one experimental composite (EX), a resin-infiltrated ceramic (VE), and a feldspar ceramic reference (VM). The crowns were adhesively bonded (Scotchbond Universal + Rely X Ultimate, 3M), and two groups (EX, VE) were additionally cemented with a self-adhesive cement (RelyX Unicem, 3M). After 90-d water storage, thermal cycling and mechanical loading (TCML) were performed. Restorations, which failed during storage or TCML, were analyzed using scanning electron microscopy, and surviving restorations were loaded to fracture. To evaluate storage effects, two materials (EX, LU) were investigated without water storage. Results: CS (7 x) and LU (2 x) exhibited debonding during 90-d storage. LU (5 x) debonded during TCML. Cement remained on the inner sides of the crowns in all cases. EX and VE survived storage and TCML without failure or debonding. Two specimens of VM exhibited cracks after TCML. Fracture forces varied between 720 N and 2155 N. Solely the results between VE and VM were not significantly different (p = 0.204). Debonding effects due to water storage were material dependent. Fracture forces in tendency (p > 0.117) were higher for self-adhesive cementation. Conclusions: Debonding and stability of CAD/CAM crowns were material dependent. Water storage affected debonding, and cementation marginally influenced performance and fracture force

Influence of placement instruments on handling of dental composite materials

Objective. Applicability and stickiness of dental composites are influential factors for the properties of those materials and so indirectly affect function, longevity and esthetics of composite restorations in the clinic. Thus, this in vitro study aimed for the influence of different placement instruments' diameter, geometries and coatings on the handling of uncured resin composite materials. Methods. A survey about application technique of resin composites, placement instrument diameter, geometry and coating, and application temperature was answered by 55 German dentists in private practice. Due to these data diverse composite placement instruments were used to perform tensile tests on PMMA plates with application forces of 1 N and 2 N (v = 35 mm/min) at 25 and 37 degrees C. Following the dosing of a certain amount of the composite (nanohybrid, microhybrid) to the tip of the composite placement instrument, unplugging forces were determined after application and unplugging was performed. Results. Unplugging forces were statistically significant different and varied between 0.27 N and 1.14 N. Stickiness of dental composites was dependent on the composite material itself as well as diameter, geometry and coating of the placement instruments. Significance. Pre-clinical testing of composite materials' stickiness by unplugging forces facilitates the assessment of its handling properties. (C) 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved

Influence of zirconia and lithium disilicate tooth- or implant-supported crowns on wear of antagonistic and adjacent teeth

PURPOSE. To investigate the influence of crown material (lithium-disilicate, 3Y-TZP zirconia) and abutment type (rigid implant, resin tooth with artificial periodontium) on wear performance of their antagonist teeth and adjacent teeth. MATERIALS AND METHODS. A mandibular left first molar (#36) with adjacent human teeth (mandibular left second premolar: #35, mandibular left second molar: #37) and antagonistic human teeth (maxillary left second premolar: #25, maxillary left first molar: #26, maxillary left second molar: #27) was prepared simulating a section of the jaw. Samples were made with extracted human molars (Reference), crowned implants (Implant), or crowned resin tooth analogues (Tooth). Crowns (tooth #36; n 16/material) were milled from lithium-disilicate (Li, IPS e.max CAD) or 3Y-TZP zirconia (Zr, IPS e.max ZirCAD, both lvoclar Vivadent). Thermal cycling and mechanical loading (TCML) in the chewing simulator were applied simulating 15 years of clinical service. Wear traces were analyzed (frequency [n], depth [mu m]) and evaluated using scanning electron pictures. Wear results were compared by one-way-ANOVA and post-hoc-Bonferroni (alpha = 0.05). RESULTS. After TCML, no visible wear traces were found on Zr. Li showed more wear traces (n = 30-31) than the reference (n = 21). Antagonistic teeth #26 showed more wear traces in contact to both ceramics (n = 27-29) than to the reference (n = 21). Strong wear traces (> 350 mu m) on antagonists and their adjacent teeth were found only in crowned groups. Abutment type influenced number and depth of wear facets on the antagonistic and adjacent teeth. CONCLUSION. The clinically relevant model with human antagonistic and adjacent teeth allowed for a limited comparison of the wear situation. The total number of wear traces and strong wear on crowns, antagonistic and adjacent teeth were influenced by crown material

Validating laboratory simulation with resin-based materials for temporary fixed denture prostheses – Results from clinical and laboratory trials

The aim of the current study was to relate an artificial aging protocol for the analysis of dental materials to their clinical performance. 20 fixed interim restorations (crowns and fixed denture prostheses (FDPs)) fabricated from two commercially available resin-based composites (RBCs) and a previous clinical trial served as templates for the fabrication of duplicate restorations. Duplicates were subjected to artificial aging using thermal cycling and mechanical loading. Subsequent to wear analysis, templates and duplicates were loaded to fracture and were examined using thermal gravimetric analysis (TG) and differential scanning calorimetry (DSC). For both RBCs, a relevant uptake of water was identified, which was more pronounced in the duplicates. Tribological analyses indicated relevant signs of wear in both templates and duplicates. While qualitative analyses indicated macroscopically similar wear traces in templates and duplicates, data showed that wear of FDPs was underrated in the laboratory analyses. The results of the current study suggest that chewing simulation allows a proper estimation of aging processes in materials for the fabrication of fixed interim restorations. However, simulation parameters should be continuously improved using data derived from clinical settings to enhance the quality of the simulation protocols