scholarly journals Adhesion of various dental luting cements to the mirror-polished surface of metallic dental materials

2020 ◽  
Vol 40 (3) ◽  
pp. 219
Author(s):  
Kuniko KOHDA ◽  
Sakae NAGASAWA ◽  
Ikufumi KURASAWA ◽  
Akio YAMAMOTO ◽  
Akihiro KUROIWA ◽  
...  
Keyword(s):  
Dental Materials ◽  
Polished Surface ◽  
Luting Cements

scholarly journals A study on fatigue toughness of dental materials. Part 1. Compressive strength on various luting cements and composite resin cores.

1989 ◽  
Vol 33 (4) ◽  
pp. 966-976 ◽  
Author(s):  
Satoshi Miyamoto ◽  
Tetsuichi Takagawa ◽  
Akira Nozaki ◽  
Nobuhiko Yanaka ◽  
Yoshiharu Nakamura ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Composite Resin ◽  
Dental Materials ◽  
Luting Cements ◽  
Resin Cores

scholarly journals Investigation of Antioxidant Capacity of Several Luting Cements Processes by HPMC Method

2016 ◽  
Vol 20 (3) ◽  
pp. 155-159
Author(s):  
Dragan V Ilić ◽  
Kosovka Obradović-Đuričić ◽  
Vesna Medic ◽  
Srđan Poštić ◽  
Stanislava Z Gorjanović ◽  
...  
Keyword(s):  
Free Radicals ◽  
Oral Cavity ◽  
Antioxidant Capacity ◽  
Oxidation Process ◽  
Composite Resin ◽  
Dental Materials ◽  
Resin Cement ◽  
Luting Cements ◽  
Entire Life ◽  
Similar Role

Summary Background: Free radicals (FR) occur in oral cavity where lot of food was transferred to through entire life under specific saliva conditions. Many enzymes, microorganism, alcohol beverages, nicotine and other harmful or indifferent substances when in contact to oral tissues might provoke oxidation process under specific condition creating FRʼs. The similar role might have various dental materials.Aim: Of the study was to record the level of antioxidant (AO) activity of several permanent (P) luting cements alone or combined with quercetin AO substance.Materials/Methods: P cements were Zn-phosphate, Zn-polycarboxilate, GIC and composite resin cement. They were prepared as original prescription and their variant by 1%weight addition of quercetin. AO activity of cements was measured by HPMC test evaluated by Student t test.Results: There were statistically significant differences among Zn-phosphate, Zn-polycarboxilate and resin dental cements (p ˃ 0,05). GIC displayed significantly higher AO values (p < 0,01) versus other three cements. There were no difference in AO capacity between sample of original P cements and their corresponding quercetin variants (p ˃ 0,05).Conclusions: Conventional GIC displayed the most powerful AO activity among P luting cements. Addition of 1% antioxidant quercetin did not improve AO capacity of investigated cements.

scholarly journals Analysis of the Performance of a Standardized Method for the Polishing of Methacrylic Resins

2009 ◽  
Vol 3 (1) ◽  
pp. 233-240 ◽  
Author(s):  
Massimo Corsalini ◽  
Antonio Boccaccio ◽  
Luciano Lamberti ◽  
Carmine Pappalettere ◽  
Santo Catapano ◽  
...  
Keyword(s):  
Human Factors ◽  
A Priori ◽  
Dental Materials ◽  
Polished Surface ◽  
Standardized Protocol ◽  
Milling Tool ◽  
Statistical Dispersion ◽  
Micro Organisms ◽  
Work Done

Adhesion of micro-organisms to resin surface may be caused by inadequate polishing. Most of the studies published in literature are relative to manually prepared samples and do not take into account that test repeatability is not guaranteeda priorisince skills may change from one operator to another and the quality of the work done by the same expert operator may depend on “human” factors such as the level of attention, wrist trembling, etc.This paper aims to investigate on the efficiency and reliability of a standardized protocol for polishing methacrylic resins. For that purpose, five different methacrylic resins are considered. For each resin, 20 specimens are realized: 10 are polished by the same expert operator and 10 are polished by means of a mechanical system comprised of a milling tool, a mobile support for samples and a micrometric advance isoparallelometer. Roughness measurements are carried out with a ±0.01 µm resolution profilometer.An extensive statistical analysis is conducted on a population of 100 specimens. Two-way Analysis of Variance (ANOVA) is carried out taking the type of resin (i) and the polishing technique (ii) as predictors in order to evaluate how those variables will finally affect the roughness of the polished surface. The significance of the variable interaction term is assessed. The null hypothesis Ho where response is independent from individual factors as well as from their interaction is assumed to hold true forp-values>0.05 (interval of confidence of the 95%).Experimental data confirm that mechanical polishing leads to obtaining surfaces of much more uniform quality. In fact, statistical dispersion of roughness parameters can decrease significantly. This behavior is observed for all of the tested resins. Therefore, the new approach can eliminate the influence of “human” factors thus making it possible to assess the inherent features of each resin and compare different dental materials submitted to polishing.

Observations on the Structure of Ta2O5

1972 ◽  
Vol 30 ◽  
pp. 540-541
Author(s):  
P. S. Kotval ◽  
C. J. Dewit
Keyword(s):  
Electron Microscope ◽  
Structural Features ◽  
Amorphous Structure ◽  
Polished Surface ◽  
Distilled Water ◽  
Anodic Films ◽  
Amorphous Films ◽  
Beam Heating ◽  
Diffraction Patterns ◽  
Hexagonal Arrays

The structure of Ta2O5 has been described in the literature in several different crystallographic forms with varying unit cell lattice parameters. Earlier studies on films of Ta2O5 produced by anodization of tantalum have revealed structural features which are not consistent with the parameters of “bulk” Ta2O5 crystalsFilms of Ta2O5 were prepared by anodizing a well-polished surface of pure tantalum sheet. The anodic films were floated off in distilled water, collected on grids, dried and directly examined in the electron microscope. In all cases the films were found to exhibit diffraction patterns representative of an amorphous structure. Using beam heating in the electron microscope, recrystallization of the amorphous films can be accomplished as shown in Fig. 1. As suggested by earlier work, the recrystallized regions exhibit diffraction patterns which consist of hexagonal arrays of main spots together with subsidiary rows of super lattice spots which develop as recrystallization progresses (Figs. 2a and b).

Material analysis techniques using the ion mill

1996 ◽  
Vol 54 ◽  
pp. 1034-1035
Author(s):  
J. P. Benedict ◽  
R. M. Anderson ◽  
S. J. Klepeis
Keyword(s):  
Polished Surface ◽  
Surface Material ◽  
Analysis Techniques ◽  
Material Analysis ◽  
Optical Inspection ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Argon Ions ◽  
The Impact ◽  
Scanning Electron

Ion mills equipped with flood guns can perform two important functions in material analysis; they can either remove material or deposit material. The ion mill holder shown in Fig. 1 is used to remove material from the polished surface of a sample for further optical inspection or SEM ( Scanning Electron Microscopy ) analysis. The sample is attached to a pohshing stud type SEM mount and placed in the ion mill holder with the polished surface of the sample pointing straight up, as shown in Fig 2. As the holder is rotating in the ion mill, Argon ions from the flood gun are directed down at the top of the sample. The impact of Argon ions against the surface of the sample causes some of the surface material to leave the sample at a material dependent, nonuniform rate. As a result, the polished surface will begin to develop topography during milling as fast sputtering materials leave behind depressions in the polished surface.

Yag Single Crystals for Scintillators of Stem

1990 ◽  
Vol 48 (1) ◽  
pp. 166-167
Author(s):  
M. Hibino ◽  
K. Irie ◽  
R. Autrata ◽  
P. schauer
Keyword(s):  
Single Crystals ◽  
Yttrium Aluminum Garnet ◽  
Light Guide ◽  
Detection System ◽  
Polished Surface ◽  
Detective Quantum Efficiency ◽  
Backscattered Electrons ◽  
Electron Detection ◽  
Yttrium Aluminum ◽  
Phosphor Screens

Although powdered phosphor screens are usually used for scintillators of STEM, it has been found that the phosphor screen of appropriate thickness should be used depending on the accelerating voltage, in order to keep high detective quantum efficiency. 1 It has been also found that the variation in sensitivity, due to granularity of phosphor screens, makes the measurement of fine electron probe difficult and that the sensitivity reduces with electron irradiation specially at high voltages.In order to find out a preferable scintillator for STEM, single crystals of YAG (yttrium aluminum garnet), which are used for detecting secondary and backscattered electrons in SEM were investigated and compared with powdered phosphor screens, at the accelerating voltages of 100kV and 1 MV. A conventional electron detection system, consisting of scintillator, light guide and PMT (Hamamatsu Photonics R268) was used for measurements. Scintillators used are YAG single crystals of 1.0 to 3.2mm thicknesses (with surfaces matted for good interface to the light guide) and of 0.8mm thickness (with polished surface), and powdered P-46 phosphor screens of 0.07mm and 1.0mm thicknesses for 100kV and 1MV, respectively. Surfaces on electron-incidence side of all scintillators are coated with reflecting layers.

“Cavity” formation in superplastically deformed aluminium alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 958-959
Author(s):  
A. Cziráki ◽  
E. Ková-csetényi ◽  
T. Torma ◽  
T. Turmezey
Keyword(s):  
Grain Boundaries ◽  
Aluminium Alloys ◽  
Superplastic Deformation ◽  
Volume Fraction ◽  
Superplastic Forming ◽  
Polished Surface ◽  
Cavity Formation ◽  
Stress Concentrations ◽  
Electron Microscopic ◽  
Commercial Aluminium

It is known that the formation of cavities during superplastic deformation can be correlated with the development of stress concentrations at irregularities along grain boundaries such as particles, ledges and triple points. In commercial aluminium alloys Al-Fe-Si particles or other coarse constituents may play an important role in cavity formation.Cavity formation during superplastic deformation was studied by optical metallography and transmission scanning electron microscopic investigations on Al-Mg-Si and Al-Mg-Mn alloys. The structure of particles was characterized by selected area diffraction and X-ray micro analysis. The volume fraction of “voids” was determined on mechanically polished surface.It was found by electron microscopy that strongly deformed regions are formed during superplastic forming at grain boundaries and around coarse particles.According to electron diffraction measurements these areas consist of small micro crystallized regions. See Fig.l.Comparing the volume fraction and morphology of cavities found by optical microscopy a good correlation was established between that of micro crystalline regions.

Intensive course in dental materials for teachers of dental auxiliaries

1973 ◽  
Vol 37 (2) ◽  
pp. 39-42
Author(s):  
JB Moser ◽  
EP Lautenschlager ◽  
BK Moore ◽  
EH Greener
Keyword(s):  
Dental Materials ◽  
Intensive Course ◽  
Dental Auxiliaries

Microbiological purity of syringes containing composites in the context of cross-infection prevention in dental practices

2020 ◽  
Vol 33 (2) ◽  
pp. 102-105
Author(s):  
Joanna Bialowska ◽  
Witold Bojar ◽  
Tomasz Zareba ◽  
Stefan Tyski ◽  
Barbara Tymczyna-Borowicz
Keyword(s):  
Infection Prevention ◽  
Dental Materials ◽  
Cross Infection ◽  
Aerobic Bacteria ◽  
Filling Material ◽  
Bodily Fluids ◽  
Dental Office ◽  
Dental Practices ◽  
Dental Offices ◽  
Aerobic And Anaerobic

AbstractCross-infection involves the transmission of microorganisms through secretions, bodily fluids and excreta, as well as undisinfected surfaces and medical equipment. In the dental office, diseases are transmitted via various routes, e.g. from patient to dentist or other member of dental team, from doctor or dental team member to patient, from patient to another patient, from dental office to community and from community to patient. The study was conducted to evaluate the effectiveness of infection control in dental practices based on the qualitative and quantitative assessment of microbiological contaminants detected on the surface of filling material packaging used in dental offices. The material for research were 9 packages containing dental materials during their use in 3 dental settings. The packages were placed in sterile flasks and rinsed to wash microorganisms from the surfaces. The washes were filtered through membrane filters and cultured under proper aerobic and anaerobic conditions, and at elevated CO2 concentration. Microbial growth on TIO and TSB media was observed. The contamination of most samples remained low as indicated by the growth from one to a maximum of five colonies on TSA. The contamination remained at the level of 10-50 CFU/package, i.e. <100 CFU/single package. The tests evaluating the contamination of dental package surfaces with aerobic bacteria confirmed high hygiene standards observed in dental offices from which the packages were brought.

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