Bond strength of a new Kevlar fiber-reinforced composite post with semi-interpenetrating polymer network (IPN) matrix

This study aimed to evaluate the bond strength and the penetration depth of two adhesive systems to a new experimental semi-IPN fiber post versus a commercial post. Experimental Kevlar fiber (KF) and control everStick®POST (ES) posts (n=20/ group) with a diameter of 1.5 mm were used, 10 posts coated with StickResin (SR) and the other 10 posts coated with Scotch bond multipurpose (SBMP) adhesives. Composite resin buildup was performed over each post, using a cylindrical plastic mold (10 mm × 6 mm). Four discs of 2 mm thickness were prepared from each post/composite buildup and underwent pushout bond strength test at a crosshead speed of 0.5 mm/min accompanied by failure mode analysis. A further three specimens from each subgroup were bonded with adhesives labeled with 0.1 wt% Rhodamine B and embedded in acrylic resin, sectioned and examined under a confocal Laser-scanning microscope (CLSM) to measure the depth of resin penetration. Statistical analysis included ANOVA and Tukey test, the significance level was assumed at a p-value less than 0.05. The push-out bond strength of KF was comparable to that of ES with both SBMP and SR adhesives (P >0.05). Bond strength value for SBMP was higher than SR adhesive in either ES and KF posts with no significant difference (P > 0.05). ES exhibited higher adhesive penetration depth compared with KF (p<0.05). The bond strength of Kevlar post was comparable with the everStick post and the semi-interpenetrating structure of Kevlar post displayed some adhesive monomers diffusion indicating its usefulness as a new intracanal post

The effect of transparency on a three-cycle model of manipulative discourse

It is assumed that manipulative discourse can carry various types of messages on the continuum of sincerity, such as: truth, persuasion (argumentation), deception and manipulation. These different intended meanings can cause variations within the ‘transparency factor’. The transparency factor is controlled by specific social and pragmatic factors. Generally speaking, manipulative discourse is far away from transparency because it entails the use of implicit strategies and processes to achieve a final goal. The highly transparent type of discourse is the testimony where the speaker’s intention is to present truth that is supported by explicit strategies and processes. Within this continuum, there is the persuasion where the speaker’s intention is to convince the addressee without exerting any power upon the receiver. Other types, such as coercion and deception, may show a lower degree of transparency because they are used to mislead the hearer with or without the use of the social effect such as ‘power’. Accordingly, a theoretical framework which treats manipulation as a three-cycle of the meaning-making process is proposed. It is assumed that this model helps in classifying manipulative texts into different types based on the transparency factors. The aim of this study is to provide a theoretical framework that can be adopted by researchers to analyze types of discourse in terms of transparency taking into consideration the speaker, the text itself and the hearer. All these factors in the three-cycle model help in shaping the degree of transparency that a text may [email protected] Rana A. Saeed Almaroof is an assistant professor in the English Department of Al-Buraimi University College in Oman. His research interests include contrastive linguistics, discourse analysis and e-learning. He is particularly interested in the application of several analytic models and model mergers to specific types of texts, e.g. religiousAl-Buraimi University College, OmanBlass, Regina. 2005. Manipulation in the speeches and writings of Hitler and the NSDAP from a relevance theoretic point of view. In: L. de Saussure and P. Schulz (eds.), Manipulation and Ideologies in the Twentieth Century: Discourse, Language, Mind, 169-190. Amsterdam/ Philadelphia: John Benjamins Publishing.Danler, Paul.2005. Morpho-syntactic and textual realizations as deliberate pragmatic argumentative linguistic tools. In: L. de Saussure and P. Schulz (eds.), Manipulation and Ideologies in the Twentieth Century: Discourse, Language, Mind, 45-60. Amsterdam/Philadelphia: John Benjamins Publishing.Emeka-Nwobia & Ngozi U.2016. Political manipulation in Nigerian presidential discourses. British Journal of English Linguistics 4(4). 12-23.Fairclough, Norman. 2003. Analysing Discourse: Textual Analysis for Social Research. London: Routledge.Graham, Peter J. 2006. Can testimony generate knowledge? Philosophica 78. 105-127.Ilie, Cornelia. 2005. An integrated approach to the analysis of participant roles in totalitarian discourse. In: L. de Saussure and P. Schulz (eds.), Manipulation and Ideologies in the Twentieth Century: Discourse, Language, Mind, 191-211. Amsterdam/Philadelphia: John Benjamins Publishing.Kamil, Salwa Ibrahim, and Fareed Hameed Al-Hindawi. 2017. The Pragmatics of Manipulation in British and American Political Debates. Hamburg: Anchor Academic Publishing.Maillat, Didier, and Steve Oswald. 2009. Defining manipulative discourse: The pragmatics of cognitive illusions. International Review of Pragmatics 1(2). 348-370.Morler, Edward E. 2006. The Leadership Integrity Challenge: Assessing and Facilitating Emotional Maturity. Tel Aviv-Yafo: Sanai Publishing.Portis, Edward Bryan, Adolf G. Gundersen, and Ruth Lessl Shively (eds.) 2000. Political Theory and Partisan Politics: Matter the Body Itself. Albany: SUNY Press.Rigotti, Eddo. 2005. Towards a typology of manipulative processes. In: L. de Saussure and P. Schulz (eds.), Manipulation and Ideologies in the Twentieth Century: Discourse, Language, Mind, 61-83. Amsterdam/Philadelphia: John Benjamins Publishing.de Saussure, Louis. 2005. Manipulation and cognitive pragmatics: Preliminary hypotheses. In: L. de Saussure and Peter J. Schulz (eds.), Manipulation and Ideologies in the Twentieth Century: Discourse, Language, Mind, 113-146. Amsterdam/Philadelphia: John Benjamins Publishing.Sorlin, Sandrine. 2016. Language and Manipulation in House of Cards: A Pragma-stylistic Perspective. London: Palgrave Macmillan.Van Dijk, Teun A.2006. Discourse and manipulation. Discourse & Society, 17(3). 359-383.Vadia, Kata. 2016. Critical discourse analysis in progress: the power, ideology and manipulation identification (PIMI) model. Alkalmazott Nyelvtudomány 16, doi: http://dx.doi.org/10.18460/ ANY.2016.1.00416 (1/2017)193

A resin composite material containing an eugenol derivative for intracanal post cementation and core build-up restoration

Objectives: To formulate and evaluate new dual cured resin composite based on the inclusion of eugenyl methacrylate monomer (EgMA) with Bis-GMA/TEGDMA resin systems for intracanal post cementation and core build-up restoration of endodontically treated teeth. Methods: EgMA was synthesized and incorporated at 5% (BTEg5) or 10% (BTEg10) into dual-cure formulations. Curing properties, viscosity, T g, radiopacity, static and dynamic mechanical properties of the composites were determined and compared with Clearfil™DC Core-Plus, a commercial dual-cure, two-component composite. Statistical analysis of the data was performed with ANOVA and the Tukey's post-hoc test. Results: The experimental composites were successfully prepared, which exhibited excellent curing depths of 4.9, 4.7 and 4.2. mm for BTEg0, BTEg5 and BTEg10 respectively, which were significantly higher than Clearfil™DC. However, the inclusion of EgMA initially led to a lower degree of cure, which increased when measured at 24. h with values comparable to formulations without EgMA, indicating post-curing. The inclusion of EgMA also lowered the polymerization exotherm thereby reducing the potential of thermal damage to host tissue. Both thermal and viscoelastic analyses confirmed the ability of the monomer to reduce the stiffness of the composites by forming a branched network. The compressive strength of BTEg5 was significantly higher than the control whilst flexural strength increased significantly from 95.9 to 114.8. MPa (BTEg5) and 121.9. MPa (BTEg10). Radiopacity of the composites was equivalent to ∼3. mm Al allowing efficient diagnosis. Significance: The incorporation of EgMA within polymerizable formulations provides a novel approach to prepare reinforced resin composite material for intracanal post cementation and core build-up and the potential to impart antibacterial properties of eugenol to endodontic restorations.</p

New functional and aesthetic composite materials used as an alternative to traditional post materials for the restoration of endodontically treated teeth

Objectives: To tailor composites of polyethylene–hydroxyapatite to function as a new intracanal post for the restoration of endodontically treated teeth (ETT). Methods: Silanated hydroxyapatite (HA) and zirconium dioxide (ZrO2) filled low-density polyethylene (LDPE) composites were fabricated by a melt extrusion process and characterised using infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The flexural strength and modulus were determined in dry state and post ageing in simulated body fluid and fractured surfaces analysed by SEM. The water uptake and radiographic appearance of the experimental composites were also measured and compared with a commercially known endodontic fibre post. Data were submitted to one-way analysis of variance (ANOVA) and post hoc Tukey multiple comparison tests at a level of significance P &lt; 0.05. Results: The LDPE/HA composites were structurally flexible and the HA content had a significant effect on the flexural strength and modulus. A univariate analysis of variance showed no significant differences in modulus and strength (P &lt; 0.05) post accelerated ageing in simulated body fluid with very low water uptake. The melting point of the LDPE/HA composites ranged between 135 and 136 C, which would facilitate removal in case of retreatment using conventional dental heating devices. The inclusion of HA reduced the damping thereby enhancing dimensional stability, whilst the addition of zirconia yielded a semi-translucent material that was sufficiently radiopaque, comparable to commercial posts, thus yielding aesthetic materials. Conclusions: Innovative materials for restoration of ETT were developed; offering considerable benefits over the currently available material in terms of biomechanical and thermal properties. Clinical significance: This study provided a new option for the development of a new intracanal post made up of functional and aesthetic composites

Evaluation of dental adhesive systems incorporating an antibacterial monomer eugenyl methacrylate (EgMA) for endodontic restorations

Objective The purpose of this study was to incorporate EgMA, an antibacterial monomer into two commercial dental adhesive systems for their application in endodontic restoration with the aim to disinfect the root canal space before curing and to inhibit bacterial growth on their surfaces after being cured. Methods EgMA monomer was added at 20% wt. into the formulation of the single-component self-etch, Clearfil Universal Bond™ (CUB) and into the catalyst and the adhesive components of the total-etch Adper Scotchbond-multipurpose™ (SBMP) adhesive systems. The degree of conversion (DC) was calculated from FTIR spectra, glass transition temperature (Tg) determined by DSC, water sorption and solubility were measured gravimetrically, and surface free energy (SFE) via contact angle measurements. The bonding performance to coronal and middle root canal dentin was assessed through push-out bond strength after filling the canals with a composite core material and the surface integrity was observed using SEM and confocal laser scanning microscopy (CLSM). The standard agar diffusion test (ADT) was used to identify the sensitivity of three endodontically pathogenic bacteria, Enterococcus faecalis, Streptococcus mutans and Propionibacterium acnes to uncured EgMA modified adhesives. Multispecies biofilm model from these strains was grown on the disc surface of cured adhesives and investigated using quantitative microbial culture and CLSM with live/dead staining. MTT assay was also used to determine the cytotoxicity of these adhesives. Results The incorporation of EgMA lowered polymerization exotherm and enhanced the hydrophobic character of these adhesives, without changing the DC and Tg in comparison to the controls (without EgMA). The total push-out bond strengths of the EgMA-containing adhesives were not significantly different from those of the controls (p &gt; 0.05). The modification of self-etch adhesive system enhanced the bond strength in the middle region of the roots canal. SEM of debonded specimens and CLSM examination showed the integrity of the resin-dentin interfaces. For all three bacteria tested, the sizes of the inhibition zones produced by uncured EgMA modified adhesives were significantly greater (p &lt; 0.05) than those of the controls. The results of biofilm inhibition tests showed less CFU for total bacteria on bonding agents with EgMA compared to the control materials (p &lt; 0.05). The modification at 20% monomer concentration had no adverse effects on cytocompatibility of both adhesives tested. Significance The inclusion of EgMA endows dental adhesives with effective antibacterial effects without influencing their curing properties, bonding ability to root canal dentin, and cytotoxicity against human gingival fibroblasts, indicating the usefulness of their application in endodontic restorations

Influence of a polymerizable eugenol derivative on the antibacterial activity and wettability of a resin composite for intracanal post cementation and core build-up restoration

Objectives Eugenol has been used in dentistry due to its ability to inhibit the growth of a range of microorganisms, including facultative anaerobes commonly isolated from infected root canals. The aim of this study was to evaluate the antibacterial activity of the experimental composites containing eugenyl methacrylate monomer (EgMA), a polymeric derivative of eugenol, against a range of oral bacteria, commonly associated with failure of coronal and endodontic restorations. In vitro composite behavior and wettability were also studied in conjunction with their antibacterial activity. Methods EgMA monomer (5 and 10% by weight) was added into BisGMA/TEGDMA resin based formulations with filler mixtures of hydroxyapatite (HA) and zirconium oxide ZrO2. The antibacterial activity of the experimental composites against Enterococcus faecalis, Streptococcus mutans and Propionibacterium acnes were evaluated by direct contact test and compared with composite formulation without inclusion of EgMA. To clarify the antibacterial mode of action, agar diffusion test (ADT) was also performed. Water sorption, solubility, diffusion coefficient, contact angle and surface free energy as complementary clinically relevant properties were determined. Results Water sorption and wettability studies showed reduction of water uptake and surface free energy values with increasing content of EgMA monomer, resulting in significant increase in the hydrophobicity of the composites. No inhibition zones were detected in any of the composites tested against the three bacteria employed as expected, due to the absence of any leachable antibacterial agent. The covalently anchored EgMA monomer with the composite surface exhibited an effective bacteriostatic activity by reducing the number of CFUs of the three species of bacteria tested with no significant dependence on the concentration of EgMA at 5 and 10% by weight. The surface antibacterial activity R of the experimental composites were different against the three tested species with values in the range 2.7-6.1 following the order E. faecalis < S. mutans < P. acnes. Significance The incorporation of EgMA monomer within polymerizable formulations provides a novel approach to yield intrinsically antibacterial resin composites for different dental applications.Peer reviewe

Assessing the Impact of Technology Learning and Assessment Method on Academic Performance: Review Paper

Technology enhancement learning is a process that leads to deep point of learning and adds knowledge of technologies. Various studies shed light on technology development and its effect in educational sector. The aim of this integrative review is to examine the current evidence of the impact of technology learning on student learning and academic performance in courses requiring collaborative or activities. The authors searched electronic databases for relevant articles, with different learning techniques. 24 articles met the requirement of paper, it’s collected from (2011-2017). Three themes of techniques used for student learning outcomes, includes technology enhanced learning, assessment method and faculty experience on academic performance in universities with technology use. The final results of this paper show the relationship between what has been done and the factors used by the authors. Also the future work needs more use of technologies in different phases of learning process

Distal revascularization and interval ligation procedure for radial-basilic forearm transposition arteriovenous fistula

The distal revascularization and interval ligation procedure is commonly performed for steal syndrome in upper arm arteriovenous accesses and is rarely performed in the forearm. We present a case of distal revascularization and interval ligation procedure performed for a 60-year-old male who presented with a 3-month history of a nonhealing ulcer of his left middle finger as a result of ischemic steal syndrome 4 years after having a left radial-basilic forearm transposition arteriovenous fistula