Search results for "ontología"
showing 10 items of 1426 documents
The effect of different insertion techniques on the depth of cure and vickers surface micro-hardness of two bulk-fill resin composite materials
2016
BACKGROUND The aim of this study was to evaluate the Vickers surface micro-hardness and the depth of cure of two bulk-fill resin composites and one incremental-fill resin composite. MATERIAL AND METHODS Two Bulk-fill dental resin composites (X-tra Fil, Voco; Sonic-FillTM 2, Kerr Corporation) and an incremental-fill dental resin composite (Filtek™ Z250 XT, 3M ESPE) were used. Sixty cylindrical specimens of 4 mm thickness were prepared using split Teflon moulds. Specimens were divided into six groups (n=10) according to the type of the material used and according to the insertion technique applied (bulk or incremental). Prepared specimens were stored dry in complete darkness at 37°C for 24 ho…
Atomic force microscopy visualization of injuries in Enterococcus faecalis surface caused by Er,Cr:YSGG and diode lasers
2014
Aim: To visualize by Atomic Force Microscopy the alterations induced on Enterococcus. faecalis surface after treatment with 2 types of laser: Erbium chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser and Diode laser. Material and Methods: Bacterial suspensions from overnight cultures of E. faecalis were irradiated during 30 seconds with the laser-lights at 1 W and 2 W of power, leaving one untreated sample as control. Surface alterations on treated E. faecalis were visualized by Atomic Force Microscopy (AFM) and its surface roughness determined. Results: AFM imaging showed that at high potency of laser both cell morphology and surface roughness resulted altered, and that several ce…
Comparative In Vitro Study of the Bond Strength of Composite to Carbon Fiber Versus Ceramic to Cobalt–Chromium Alloys Frameworks for Fixed Dental Pro…
2020
Purpose: The aim of this comparative in vitro study was to assess the bond strength and mechanical failure of carbon-fiber-reinforced composites against cobalt&ndash
Effect of glycine pretreatment on the shear bond strength of a CAD/CAM resin nano ceramic material to dentin
2016
Background: The purpose of this study was to evaluate the effect of glycine pretreatment on the shear bond strength between dentin and a CAD/CAM resin nano ceramic material (LavaTM Ultimate Restorative), bonded together with adhesive cements using three different luting protocols (total-etch; self-etch; self-adhesive). Material and Methods: Thirty cylinders were milled from resin nano ceramic blocks with CAD/CAM technology. The cylinders were subsequently cemented to the exposed dentin of 30 bovine permanent mandibular incisors. The specimens were assigned into six groups of five teeth each according to luting procedure and dentin pretreatment. In the first two groups (A1, A2) 10 cylinders …
A portable fiber-optic raman spectrometer concept for evaluation of mineral content within enamel tissue
2017
BACKGROUND Measurement of tooth enamel mineralization using a clinically viable method is essential since variation of mineralization may be used to monitor caries risk or in assessing the effectiveness of remineralization therapy. Fiber optic Raman systems are becoming more affordable and popular in context of biomedical applications. However, the applicability of fiber optic Raman systems for measurement of mineral content within enamel tissue has not been elucidated significantly in the prior literature. MATERIAL AND METHODS Human teeth with varying degrees of enamel mineralization were selected. In addition alligator, boar and buffalo teeth which have increasing amount of mineral conten…
Influence of adhesive systems on microtensile bond strength of resin-based endodontic sealers to the root dentin
2014
Objective: The aim of this study was to determine the microtensile bond strength to root dentin of AH PlusTM and EndoREZ® with Clearfil Liner Bond 2V and Optibond SoloTM Plus adhesive systems. Study Design: The coronal and middle thirds of six single rooted bovine teeth was split longitudinally in a mesio- distal direction. The two halves were joined with AH Plus or EndoREZ, with and without the use of Clearfil Li - ner Bond 2V and Optibond SoloTM Plus adhesive systems. Build-ups were vertically sectioned into quadrangular (?1mmx1mm) compound bars and subjected to tensile tests at a constant crosshead speed (1 mm/min) until debon - ding. Results: Optibond ® Solo PlusTM in combination with A…
Fracture resistance of tooth restored with four glass fiber post systems of varying surface geometries-An in vitro study
2016
Background The purpose of this study was to relate the fracture resistance of endodontically treated teeth in relation to post geometry. Material and methods Forty single rooted mandibular premolars were instrumented by step - back technique and obturated by lateral condensation. Forty teeth were randomly divided into four groups: Reforpost glass fiber X-ray®, RelyX®, Exacto conical® and Parapost Fiber Lux®. The post spaces were prepared using respective drills and luted. The core build up was done and metal crowns were luted. Fracture resistance was determined in universal testing machine. The statistical analysis was done using one way ANOVA and post hoc Tukey Kramer test. Results The tee…
Effect of pre-heating on the mechanical properties of silorane-based and methacrylate-based composites
2016
Background The use of composites in dental restoration has been commonly criticized, due to their underwhelming mechanical properties. This problem may be solved partially by preheating. The present research aims to determine the effect of preheating on the mechanical properties of two different classes of composites. Material and methods A Silorane-based (Silorane) and a Methacrylate-based (Z250) composite were preheated to different temperatures (25, 37, and 68 °C) and afterwards were tested with the appropriate devices for each testing protocol. The material's flexural strength, elastic modulus, and Vickers microhardness were evaluated. Two-way ANOVA, and Tukey's post hoc were used to an…
Light transmittance of zirconia as a function of thickness and microhardness of resin cements under different thicknesses of zirconia
2012
Objective: The objective of this study was to compare microhardness of resin cements under different thicknesses of zirconia and the light transmittance of zirconia as a function of thickness. Study design: A total of 126 disc-shaped specimens (2 mm in height and 5 mm in diameter) were prepared from dual-cured resin cements (RelyX Unicem, Panavia F and Clearfil SA cement). Photoactivation was performed by using quartz tungsten halogen and light emitting diode light curing units under different thicknesses of zirconia. Then the specimens (n=7/per group) were stored in dry conditions in total dark at 37°C for 24 h. The Vicker's hardness test was performed on the resin cement layer with a micr…
Effect of resin thickness, and curing time on the micro-hardness of bulk-fill resin composites
2015
Background: Bulk-fill resin composite has been introduced, their manufacturers claimed that they can be applied in bulks of 4mm, without necessitating a prolonged curing time, or a light curing unit with increased irradiance. Thus this study was conducted to evaluate the effect of resin thickness, and curing time on the micro-hardness of two bulk -fill resin composites; Tetric Evo-Ceram [TE], and X-trafil [XF]. Material and Methods: 120 cylindrical specimens were prepared, and divided into 24 groups (n=5/group), representing the two bulk-fill resin composites, three different material thicknesses (2, 3 and 4 mm) and the four curing times used in the study (10, 20, 40, and 60 seconds). The s…