Search results for "abrasion"
showing 10 items of 50 documents
Species-specific enamel differences in hardness and abrasion resistance between the permanent incisors of cattle (Bos primigenius taurus) and the eve…
2022
Hypselodont (ever-growing) teeth of lagomorphs or rodents have higher wear rates (of a magnitude of mm/week), with compensating growth rates, compared to the non-ever-growing teeth of ungulates (with a magnitude of mm/year). Whether this is due to a fundamental difference in enamel hardness has not been investigated so far. We prepared enamel samples (n = 120 per species) from incisors of cattle (Bos primigenius taurus) and nutria (Myocastor coypus, hypselodont incisors) taken at slaughterhouses, and submitted them to indentation hardness testing. Subsequently, samples were split into 4 groups per species (n = 24 per species and group) that were assessed for abrasion susceptibility by a sta…
Search for magnetic minerals in Martian rocks: Overview of the Rock Abrasion Tool (RAT) magnet investigation on Spirit and Opportunity
2008
[1] The Rock Abrasion Tool (RAT) on board the Mars Exploration Rovers (MER) is a grinding tool designed to remove dust coatings and/or weathering rinds from rocks and expose fresh rock material. Four magnets of different strengths that are built into the structure of the RAT have been attracting substantial amounts of magnetic material during RAT activities from rocks throughout both rover missions. The RAT magnet experiment as performed on Spirit demonstrates the presence of a strongly ferrimagnetic phase in Gusev crater rocks, which based on Mossbauer and visible/near-infrared reflectance spectra is interpreted as magnetite. The amount of abraded rock material adhering to the magnets vari…
Minimal intervention in dentistry: Which is the best approach for silorane composite restoration repairs?
2021
Made available in DSpace on 2021-06-25T10:28:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Background: This study aimed to evaluate surface treatments, adhesives and composites for repairing silorane based restorations. Material and Methods: One hundred and twenty truncated cones (2 mm smaller diameter and 4 mm larger diameter) made of silorane composite were divided in 12 groups according with the surface treatment (diamond bur and oxide aluminum abrasion), the adhesive (Adper Scothbond Multipurpose (3M ESPE), Ecusit (Voco) and Filtek P90 Adhesive (3M ESPE)). Each group was subdivided in two according with the composite used for repair (methacrylate and silorane). The rep…
Repair bond strength of bulk fill composites after different adhesion protocols
2019
Background Repairs in composite resin restorations are common procedures in clinical practice. Many surface treatment options have been proposed to improve the adhesion between the old and new composite. The objective of this study was to evaluate the microtensile bond strength of repairs performed on aged bulk fill and conventional composites after different adhesion protocols. Material and methods First, 84 specimens (8x8x4 mm3) of a microhybrid composite and a high-viscosity bulk fill composite were prepared and aged. Afterward, they received a mechanical surface treatment by means of abrasion with a diamond bur, followed by division into six groups according to the adhesion protocol emp…
Prediction of Tool Wear Progress in Machining of Carbon Steel using different Tool Wear Mechanismsl
2008
In this paper the prediction of tool wear on carbide uncoated tools was taken into account. In particular, two different tool wear models based on the diffusion mechanism and on the abrasion mechanism were considered. The calibration of the utilized models was done using the results obtained by experimental analysis performed on an orthogonally machined AISI 1020 tube. Once the calibration was executed, numerical simulations, for both the utilized tool wear models, were simultaneously performed with the aim to test the capability of the proposed numerical procedure. The comparison between the two tool wear mechanisms for predicting the flank tool wear is discussed in the paper.
Retention strength of ball-attachment titanium post for removable partial denture or overdenture
2020
Aim: To evaluate the retention of an endodontic titanium post with a spherical head for removable partial denture or overdenture attachment according to surface treatment type. Methods: Sixty healthy single-rooted teeth, sectioned at the enamel/cementum junction, were treated endodontically and steadily fixed in the embedding acrylic resin. The titanium posts were subdivided into four groups: control, no surface treatment (Ctrl); posts with macro-retentive grooves (MR); air abrasion of the post surface (AB); and posts with macro-retentive grooves and air abrasion of the post surface (MR+AB). The posts were luted in the root canal using self-adhesive dual resin cement. Pull-out testing was p…
Effect of diamond microdermabrasion on oily skin: a case report
2018
Background: The history of microdermabrasion dates back to ancient Egypt. The first treatment in Europe occurred in 1985 and has since become a popular method of exfoliation of the superficial layers of skin. Microdermabrasion is an effective method of taking care of the skin of the face and body, bringing about immediate effects in the treatment of deep scars and stretch marks. Aim of the study: To determine the effectiveness of diamond microdermabrasion on a person with hyperuricemia of the sebaceous glands. Materials and methods: Based on interviews, a case analysis, and the impact of diamond microdermabrasion on the structure of the skin’s surface, the level of hydration, oiliness and e…
Reactive Powder Concrete Containing Basalt Fibers: Strength, Abrasion and Porosity
2020
The paper presents the test results of basalt fiber impact on a compressive and flexural strength, resistance to abrasion and porosity of Reactive Powder Concrete (RPC). The reasons for testing were interesting mechanical properties of basalt fibers, the significant tensile strength and flexural strength, and in particular the resistance to high temperatures, as well as a relatively small number of RPC tests performed with those fibers and different opinions regarding the impact of those fibers on concrete strength. The composition of the concrete mix was optimized to obtain the highest packing density of particles in the composite, based on the optimum particle size distribution curve acc.…
Evaluation of retention of pit and fissure sealants placed with and without air abrasion pretreatment in 6-8 year old children – An in vivo study
2017
Background The success of pit and fissure sealants is directly related to their retention. The purpose of this study was to assess and compare the retention of pit and fissure sealants placed using acid etch alone and a combination of air abrasion and acid etch techniques. Material and Methods 50 subjects aged 6-8 years were included in the study. Primary second molars and permanent first molars were sealed in all four quadrants using split mouth design. The right maxillary and mandibular molars (Group A) were treated by acid etching alone while the left maxillary and mandibular molars (Group B) were pretreated with air abrasion followed by acid etching before application of pit and fissure…
Assessment of non-carious root surface defects in areas of gingival recession: A descriptive study.
2015
BACKGROUND The purpose of this descriptive study was to observe the distribution of four different classes of non-carious cervical root surface discrepancies in teeth with gingival recession. Additionally to explore the different treatment modalities in the literature for each of these defects. MATERIAL AND METHODS A total of 150 subjects with at least one labial gingival recession were included in the study. 1400 teeth were evaluated using 2.5 X magnification loupes and UNC -15 probe for the presence of the cemento-enamel junction and step like defects according to Pini-Prato's classification: A-, identifiable CEJ without defect; A+, identifiable CEJ with defect; B-, unidentifiable CEJ wit…