Search results for "visual_art"
showing 10 items of 2987 documents
Do viscosity and wettability of fluoride varnishes affect their fluoride release?
2020
BACKGROUND: There are several brands of fluoride varnishes in the market, but the dynamics of fluoride release from each one might be different. The purpose of this study was to evaluate in vitro the release of fluorides by fluoride varnishes and to determine the correlation with viscosity and wettability. MATERIAL AND METHODS: Forty four enamel blocks 5x5 mm were randomly divided into 4 groups (n=11) ((Duraphat®, Clinpro™ White Varnish, Flúor Protector® and control). We applied 30 milligrams of fluoride varnish to each specimen. The specimens were immersed in a Calcium Phosphate solution at a pH= 6.0. We evaluated the release of fluoride, by using a selective fluoride electrode, during 6 w…
The effect of protocol for disinfection of extracted teeth recommended by center for disease control (CDC) on microhardness of enamel and dentin
2015
Background: According to the guideline of the United States center for disease control (CDC), the extracted teeth should be sterilized by autoclaving or storage in 10% formalin before using for educational or research purposes. The objective of this study was to evaluate the effect of this protocol on microhardness of dentin and enamel. Material and Methods: Thirty extracted single-root teeth were used in this study. The crowns were resected, and the roots were longitudinally sectioned into two halves. The Vickers microhardness (VHN) of specimens was measured on polished canal dentin and buccal enamel surfaces. The crowns were randomly divided into three groups (n=10). Group 1 and 2 were st…
Combined effects of electric toothbrushing and dentifrice on artificial stain removal : an in vitro study
2018
This in vitro study aimed to clarify the combined effect of electric toothbrushing and dentifrice on the removal of artificial stain. Twenty-five bovine incisors were cut at the cervix and the crown was embedded in auto-cured acrylic resin. Specimens were abraded using #240 SiC paper to obtain a flat enamel surface, and 20 specimens were treated with 10% citric acid / 3% ferric chloride solution followed by 1% tannic acid solution to produce surface staining. They were divided into four groups: 1) brushing with an electric toothbrush and whitening dentifrice (group S+B); 2) brushing with an electric toothbrush and fluoride dentifrice (group S+C); 3) brushing with an electric toothbrush and …
Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation – Part 1: M…
2012
Bioapatite in mammalian teeth is readily preserved in continental sediments and represents a very important archive for reconstructions of environment and climate evolution. This project provides a comprehensive data base of major, minor and trace element and isotope tracers for tooth apatite using a variety of microanalytical techniques. The aim is to identify specific sedimentary environments and to improve our understanding on the interaction between internal metabolic processes during tooth formation and external nutritional control and secondary alteration effects. Here, we use the electron microprobe to determine the major and minor element contents of fossil and modern molar enamel, …
Comparison of three adhesive systems in class II composite restorations in endodontically treated teeth : influence of Er:YAG laser conditioning and …
2018
Background Dental surface conditioning by Er:YAG laser is currently being investigated, as not all of the mechanisms and effects of this technique have been clearly studied. Thus, the aim of the present study was to assess the cervical microleakage of Class II resin composite restorations in endodontically treated teeth following either the respective conventional conditioning or additional Er:YAG laser conditioning, in association with varied adhesives. Material and methods Standardized mesial-occlusal-distal cavities (two gingival walls positioned in dentin and enamel, respectively) were created in 60 extracted human premolar teeth. Following the completion of the endodontic therapy, the …
ROUGHNESS CONTROL OF PARTS OBTAINED THROUGH INCREMENTAL SHEET FORMING
2007
Abstract The present paper adresses the issue of controlling the quality of surface in the case of a new sheet metal forming process by which various curved shells are formed without the help of expensive dies. The roughness of the surface which comes in direct contact with the punch at incremental sheet forming suffers an obvious worsening compared to the initial blank surface roughness. The present paper discusses the measuring of the roughness of parts obtained through the previously mentioned process and highlights the factors that influence it. There were taken into account the initial roughness of the punch, the punch diameter and the friction coefficient between the punch and the bla…
Robot-Forming - An Incremental Forming Process Using an Industrial Robot by Means of DELMIA Software Package
2013
The purpose of this research is to present an alternative method for manufacturing sheet metal parts using an asymmetric incremental forming process by means of an industrial robot. This method is based on designing, simulating and generating the toolpath for the tool attached to the robot using DELMIA software package. The proposed approach allows users to check for system collisions, robot joins limitations and singularity problems. After a comprehensive simulation of the movements of the robot is performed, the program code can be generated by means of a specific DELMIA function. The program can be used afterwards to control the robot during the experimental work. In order to demonstrate…
On-Line Control of Single Point Incremental Forming Operations through Punch Force Monitoring
2006
Abstract Among the innovative sheet metal forming processes, Single Point Incremental Forming (SPIF) represents the simplest and the cheapest one. Despite its relevant advantages, up to now no specific CAE tools for SPIF were developed and the tool trajectory is generally defined utilizing CAD/CAM software developed for machining applications. In the paper an innovative monitoring and control approach, aimed to define and in-process update the most relevant process parameters during an industrial SPIF operation, is proposed. The strategy utilizes as monitoring variable the punch force trend: a set of preliminary tests demonstrated, in fact, its suitability as “spy variable” of the process m…
Experimental Researches Regarding Strain Measurement of Incrementally Formed Sheet Metal Parts Done Using an Industrial Robot
2014
This paper aims to provide results regarding the measurement of the strains in the material of sheet metal parts which have been incrementally formed. The incremental forming of the steel sheets has been performed with the aid of a KUKA KR 6 industrial robot on a specially constructed stand, and the measurement of the strains has been done using ARAMIS optical measurement system. The trajectory of the forming punch which is attached to the robot was designed using CATIA V5 and the movements of the robot were designed and simulated in DELMIA software. DELMIA generated the program code needed for the robot to execute the desired movements in order to form the sheet metal parts.
Cutting Tool Materials
2008
This chapter provides the state-of-the-art materials engineering sector that produces cutting tool materials for different manufacturing branches. It highlights the special demands on this special material group for modern machining technologies. Five groups of cutting tool materials are characterized in terms of their mechanical and thermo-physical properties: high-speed steels, sintered tungsten carbides, cermets, ceramics and superhard materials, all as conventional (uncoated) and coated grades. The most popular techniques of coating deposition on various substrates are described. Practical examples of cutting tool inserts made of various materials produced by leading world manufacturers…