Search results for "shear bond"
showing 9 items of 39 documents
Shear bond strength of ceramic fused to CAD-CAM milled alloys
2018
Background This study evaluated the metal ceramic bond strength of cast Ni-Cr, cast Co-Cr, sintered Co-Cr and milled Co-Cr alloys to ceramic through two application procedures including the ceramic layering technique and ceramic pressed-on technique. Material and Methods Ceramic materials (Ø 8 mm, 1.5 mm thickness) were veneered by either the layering or pressed-on technique to cast Ni-Cr, cast Co-Cr, sintered Co-Cr and hard milled Co-Cr alloy disc (12 × 12 × 0.5 mm) (n=15). All specimens were treated with a thermal cycle process for 500 cycles at the temperature between 5 °C and 55 °C with immerse time of 30 seconds and 5 seconds for specimen transfer. The shear bond strength was determine…
Advances in experimental characterization and modelling of FRCM composites for structural retrofitting
2023
Questa tesi presenta i risultati di una campagna sperimentale incentrata sulla caratterizzazione della trazione dei basalt e glass FRCM e della caratterizzazione del legame di aderenza composito-Calcarenite. Il lavoro sperimentale è completato dalla proposta di due modelli numerici sia per prove di trazione che per quelle di aderenza. L'indagine sperimentale è stata condotta considerando l'influenza di diversi rinforzi, matrici e metodi di prova. I risultati sperimentali consentono di valutare l'effetto della malta sulle curve sforzo-deformazione, la resistenza, la duttilità e le modalità di crisi. Inoltre, la tesi fornisce un importante contributo per valutare l'influenza di diversi metodi…
Numerical Modelling of the Constitutive Behaviour of FRCM Composites through the Use of Truss Elements
2023
The modeling of the mechanical behavior of Fabric Reinforced Cementitious Matrix (FRCM) composites is a difficult task due to the complex mechanisms established at the fibre-matrix and composite-support interface level. Recently, several modeling approaches have been proposed to simulate the mechanical response of FRCM strengthening systems, however a simple and reliable procedure is still missing. In this paper, two simplified numerical models are proposed to simulate the tensile and shear bond behavior of FRCM composites. Both models take advantage of truss and non-linear spring elements to simulate the material components and the interface. The proposed approach enables us to deduce the …
An in vitro evaluation of the effect of sandblasting and laser surface treatment on the shear bond strength of a composite resin to the facial surfac…
2015
Objectives: The present study was conducted to evaluate the optimal method of enhancing the bond strength of a composite resin to the facial surface of the primary anterior stainless steel crowns using various surface treatments namely Nd: YAG laser surface treatment, sandblasting , alloy primer application and no surface treatment. Study Design: The study sample consisted of 60 primary anterior stainless steel crowns (UnitekTM size R 4), with 15 samples randomly divided into the 4 study groups, embedded in acrylic blocks. The facial surface of these surface treated crowns was utilized as the bonding surface to which 2.5mm diameter composite resin cylinders were bonded for the evaluation of…
Effect of surface treatment with sandblasting and Er,Cr:YSGG laser on bonding of stainless steel orthodontic brackets to silver amalgam
2011
Objectives: Satisfactory bonding of orthodontic attachments to amalgam is a challenge for orthodontists. The aim of this in vitro study was to compare the shear bond strength of stainless steel orthodontic brackets to silver amalgam treated with sandblasting and Er,Cr:YSGG laser. Study Design: Fifty-four amalgam discs were prepared, polished and divided into three groups: In group 1 (the control group) the premolar brackets were bonded using Panavia F resin cement without any surface treatment; in groups 2 and 3, the specimens were subjected to sandblasting and Er,Cr:YSGG laser respectively, before bracket bonding. After immersing in distilled water at 37°C for 24 hours, all the specimens w…
Effect of antioxidants on the shear bond strength of composite resin to enamel following extra-coronal bleaching
2019
Background Recently patients need faster treatments, and delaying restoration is not possible following bleaching treatment. The purpose of this study was to determine the effect of antioxidants, namely 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea and 10% Aloe vera extract on the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide. Material and Methods Seventy premolars were randomly assigned into 7 groups of 10 each. Group 1: bleaching treatment and no antioxidants application. Group 2: composite was built-up immediately after bleaching. Group 3: bleached specimens received composite build-up delayed by 2 weeks. Group …
Experimental investigation on tensile and shear bond behaviour of Basalt-FRCM composites for strengthening calcarenite masonry elements
2023
The use of Fabric Reinforced Cementitious Matrix (FRCM) composites for structural retrofit has seen an increased interest among the scientific community, during the last decade. Various studies have revealed their effectiveness as external retrofitting technique of masonry elements, offering numerous advantages respect to the well know Fibre Reinforced Polymer (FRP) in terms of compatibility with masonry support, reversibility of intervention and sustainability. Despite the growing use, the characterization of FRCM mechanical behaviour is still an open issue, due to numerous uncertainties involved in test set-up adopted and fibre-mortar combination. The proposed experimental study aims to i…
Shear bond strength of one-step self-etch adhesives to dentin: Evaluation of NaOCl pretreatment
2018
Background The aim of this study was to evaluate the influence of dentin pretreatment with NaOCl on shear bond strength of four one-step self-etch adhesives with different pH values. Material and methods Bovine permanent incisors were used. Four one-step self-etch adhesives were tested: Adper™ Easy Bond, Futurabond NR, G-aenial Bond, Clearfil S3 Bond. One two-step self-etch adhesive (Clearfil SE Bond) was used as control. Group 1- no pretreatment; group 2- pretratment with 5,25 % NaOCl; group 3- pretreatment with 37 % H3PO4 etching and 5,25 % NaOCl. A hybrid composite resin was inserted into the dentin surface. The specimens were tested in a universal testing machine. The examiners evaluate…
Microleakage and shear bond strength of orthodontc brackets bonded to hypomineralized enamel following different surface preparations
2014
Objectives: This study investigated the effects of several conditioning methods on shear bond strength (SBS) and microleakage of orthodontic brackets bonded to demineralized enamel. Study Design: One hundred premolars were selected and immersed in a cariogenic solution for 12 weeks. The teeth were randomly assigned into 5 groups. In groups 1 and 2, the teeth underwent acid etching for 30 and 120 seconds, respectively. In group 3, a combination of laser and acid etching was employed. A self-etch primer (SEP) was applied in group 4 and in group 5, the teeth were exposed to acidulated phosphate fluoride (APF) for 4 minutes before etching. After bracket bonding, the teeth were immersed in methy…