scholarly journals Longer-Term Postcure Measurement of Cuspal Deformation Induced by Dimensional Changes in Dental Materials

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
A. Falsafi ◽  
J. D. Oxman ◽  
P.-H. Tse ◽  
T. T. Ton
Keyword(s):  
Dental Materials ◽  
Displacement Transducer ◽  
Linear Variable Differential Transformer ◽  
Measuring Instrument ◽  
Direct Examination ◽  
Dimensional Changes ◽  
In Situ Techniques ◽  
Oral Conditions

Aim. This paper presents a simple, versatile in vitro methodology that enables indirect quantification of shrinkage and expansion stresses under clinically relevant conditions without the need for a dedicated instrument.Methods. For shrinkage effects, resulting cusp deformation of aluminum blocks with MOD type cavity, filled with novel filling compositions and commercial cements, has been measured using a bench-top micrometer and a Linear Variable Differential Transformer (LVDT, a displacement transducer) based instrument.Results. The results demonstrated the validity of the proposed simple methodology. The technique was successfully used in longer-term measurements of shrinkage and expansion stress for several dental compositions.Conclusions. In contrast to in situ techniques where a measuring instrument is dedicated to the sample and its data collection, the proposed simple methodology allows for transfer of the samples to the environment of choice for storage and conditioning. The presented technique can be reliably used to quantify stress development of curing materials under clinically relevant (oral) conditions. This enables direct examination and comparison of structural properties corresponding to the final stage of formed networks. The proposed methodology is directly applicable to the study of self-curing systems as they require mouth-type conditions (temperature and humidity) to achieve their designed kinetics and reactions.

scholarly journals Adhesion of Hydroxyapatite Nanoparticles to Dental Materials under Oral Conditions

Scanning ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Cíntia Mirela Guimarães Nobre ◽  
Norbert Pütz ◽  
Matthias Hannig
Keyword(s):  
Electron Microscopy ◽  
Dental Materials ◽  
Hydroxyapatite Nanoparticles ◽  
Pellicle Formation ◽  
Transmission Electron ◽  
Different Shapes ◽  
Oral Conditions ◽  
Dental Applications

Hydroxyapatite nanoparticles (nano-HAP) are receiving considerable attention for dental applications, and their adhesion to enamel is well established. However, there are no reports concerning the effects of HAP on other dental materials, and most of the studies in this field are based on in vitro designs, neglecting the salivary pellicle-apatite interactions. Thus, this in situ pilot study aims to evaluate the effects of three hydroxyapatite-based solutions and their interactions with different dental material surfaces under oral conditions. Hence, two volunteers carried intraoral splints with mounted samples from enamel and from three dental materials: titanium, ceramics, and polymethyl-methacrylate (PMMA). Three HAP watery solutions (5%) were prepared with different shapes and sizes of nano-HAP (HAP I, HAP II, HAP III). After 3 min of pellicle formation, 10 ml rinse was performed during 30 sec. Rinsing with water served as control. Samples were accessed immediately after rinsing, 30 min and 2 h after rinsing. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the particles, and SEM evaluated the pellicle-HAP interactions. SEM and TEM results showed a high variation in the size range of the particles applied. A heterogeneous HAP layer was present after 2 h on enamel, titanium, ceramics, and PMMA surfaces under oral conditions. Bridge-like structures were visible between the nano-HAP and the pellicle formed on enamel, titanium, and PMMA surfaces. In conclusion, nano-HAP can adhere not only to enamel but also to artificial dental surfaces under oral conditions. The experiment showed that the acquired pellicle act as a bridge between the nano-HAP and the materials’ surface.

scholarly journals Effect of Cavity Disinfectants on Adhesion to Primary Teeth—A Systematic Review

2021 ◽  
Vol 22 (9) ◽  
pp. 4398
Author(s):  
Ana Coelho ◽  
Inês Amaro ◽  
Ana Apolónio ◽  
Anabela Paula ◽  
José Saraiva ◽  
...  
Keyword(s):  
Primary Teeth ◽  
Clinical Success ◽  
Dental Materials ◽  
In Vitro Study ◽  
In Vitro Studies ◽  
Cochrane Library ◽  
Promising Alternative

Some authors have been proposing the use of cavity disinfectants in order to reduce, or even eliminate, the effect of the microorganisms present in a dental cavity before a restoration is placed. The aim of this study was to evaluate the effect of different cavity disinfectants on bond strength and clinical success of composite and glass ionomer restorations on primary teeth. The research was conducted using Cochrane Library, PubMed/MEDLINE, SCOPUS, and Web of Science for articles published up to February 2021. The search was performed according to the PICO strategy. The evaluation of the methodological quality of each in vitro study was assessed using the CONSORT checklist for reporting in vitro studies on dental materials. Sixteen in vitro studies and one in situ study fulfilled the inclusion criteria and were analyzed. Chlorhexidine was the most studied cavity disinfectant, and its use does not compromise dentin bonding. Sodium hypochlorite is a promising alternative, but more research on its use is required to clearly state that it can safely be used as a cavity disinfectant for primary teeth. Although other disinfectants were studied, there is a low-level evidence attesting their effects on adhesion, therefore their use should be avoided.

Determinants of pressure exerted by medical compression stockings

Phlebologie ◽  
2007 ◽  
Vol 36 (05) ◽  
pp. 237-244 ◽  
Author(s):  
B. Lun ◽  
J. F. Uhl ◽  
Y. Bringer ◽  
W. Blättler
Keyword(s):  
Muscle Activation ◽  
Compression Stocking ◽  
Relative Role ◽  
Pressure Amplitude ◽  
Interface Pressure ◽  
Compression Stockings ◽  
In Situ Techniques ◽  
The One

Summary Objective: The force exerted on a limb by a medical compression stocking (MCS) is given by the properties of the yarn and the technique of knitting. The pressure determined by the manufacturer should be the one acting on the leg provided the stocking fits the leg shape. However, the interface pressure is governed by additional factors which act simultaneously in a poorly defined manner. We sorted out the different material- and patient-related components and assessed their relative role combining in vitro with in situ techniques. Design and method: The force exerted by the stockings was measured with the Zwick and Hosy dynamometers and the pressure exerted on the leg with the SIGaT instrument placed underneath the stockings at various sites. Leg circumference was determined with the Perometer and local radius calculated from computer tomographic slices and assessed with templates. Stockings exerting ankle pressures between 10 and 40 mmHg were tested. Subjects serving in the various experiments were selected from a pool of 28 healthy volunteers. Results: All stockings exerted the predefined pressure when measured at the stocking/leg-interface (in situ) and on the dynamometer (in vitro) provided the local leg curvature was taken into account. The stockings showed slightly different elastic properties (pressure amplitude difference upon leg movement 2–6mmHg). The interface pressure varied significantly when measured at different angular positions on the same circumference (range of change +40%; –20%). The differences were strongly correlated with the local radius (range of variation along the calf circumference 35–125 mm). The differences of local radii got smaller with higher interface pressures. Leg movements provoked simultaneous increases and decreases of interface pressure of up to 15 mmHg depending on the site of measurement. Leg circumference varied only slightly with movements pointing in either direction: 0.25 cm at the ankle (range +0.4; –0.4) and 0.33 cm at the calf (range +1.05; –1.45), respectively. The compressibility of the underlying tissue had no effect on the interface pressure. Conclusions: The interface pressure can be assessed reliably in vitro and in situ. It shows complex, quantitatively important non-uniform local variations both when measured along a given leg circumference at rest and when monitored at one particular site during movements. The changes reflect the discontinuity of the leg configuration and further alterations of the silhouette occurring with every muscle activation. Clearly, a massage effect of stockings is documented which does not necessarily reflect a global effect exerted on the leg.

In vitro and in situ nutrient degradability of barley and wheat milling byproducts

1998 ◽  
Vol 78 (3) ◽  
pp. 457-459 ◽  
Author(s):  
A. F. Mustafa ◽  
J. J. McKinnon ◽  
D. A. Christensen
Keyword(s):  
Key Words ◽  
Grain Weight ◽  
In Situ Techniques ◽  
Comparison Results ◽  
Key Words Barley

A study was conducted to estimate nutrient degradability of barley milling byproducts (BMBP) using in vitro and in situ techniques. Three levels of milling (5.9, 9.5 and 17%), representing the proportion of byproduct to the original grain weight were tested. A wheat byproduct (WMBP), milled at 5.9% was used for comparison. Results indicated that 5.9% WMBP was more degradable than the BMBP. Within the BMBP, the 17% BMBP was more degradable than the 5.9 and the 9.5% BMBP. No differences in nutrient degradability were observed between the 5.9 and the 9.5% BMBP. Key words: Barley, wheat, milling byproducts, nutrient degradability

scholarly journals In vitro and in situ techniques yield different estimates of ruminal disappearance of barley

2019 ◽  
Vol 4 (1) ◽  
pp. 141-148 ◽  
Author(s):  
Mary E DeFeo ◽  
Kelsey V Shampoe ◽  
Pedro H V Carvalho ◽  
Flavia A S Silva ◽  
Tara L Felix
Keyword(s):  
Repeated Measures ◽  
Neutral Detergent Fiber ◽  
Laboratory Methods ◽  
Hulless Barley ◽  
In Vitro Techniques ◽  
In Situ Techniques ◽  
In Vitro Incubation ◽  
Ruminal Degradation

Abstract Objectives were to compare in vitro and in situ disappearance of dry matter (DM), neutral detergent fiber (NDF), and starch of traditional (unprocessed and rolled) and hulless (unprocessed) barley. Experiment 1: three barley sources were compared using in vitro techniques. The sources were: 1) traditional barley that was not processed, 2) traditional barley processed through a roller mill, and 3) hulless barley that was not processed. For in vitro incubation, each barley source was ground through a 1-mm screen. Ground barley sources were weighed into bags (25 micron porosity) and incubated in ruminal fluid from two steers fed 80% rolled corn for 3, 6, 12, 24, 48, or 72 h. Intact bags were assayed for NDF; remaining bags were opened and the residual was removed and analyzed to determine disappearance of DM and starch. Experiment 2: the barley sources used in Exp. 1 were compared using in situ techniques. For in situ analysis, each barley source was ground in a Wiley mill with no screen to mimic mastication. Artificially masticated samples were weighed into Dacron bags (50 ± 10 micron porosity) and incubated in eight ruminally fistulated steers (n = 8) for 3, 6, 12, 24, 48, and 72 h. Residual contents were analyzed to determine in situ disappearance of DM, NDF, and starch. Data were analyzed using the MIXED procedures of SAS (9.4 SAS Institute, Cary, NC) with repeated measures. DM disappearance was greatest (P < 0.05) for hulless barley in vitro and for rolled barley in situ, regardless of time postincubation. For both trials, NDF disappearance was greatest (P < 0.05) for hulless barley, regardless of time postincubation. Starch disappearance at all time points was greatest (P < 0.05) for rolled barley in situ. Starch disappearance was greater (P < 0.05) for hulless barley at 6 h of in vitro incubation compared to rolled and unprocessed barley, whereas starch disappearance in vitro was comparable (P = 0.60) between barley sources. When the grains were compared in vitro, minor differences were noted, presumably because barley sources were finely ground prior to incubation. Compared to in vitro estimates, in situ techniques had greater variation in ruminal degradation estimates. Differences observed between in situ and in vitro techniques are driven largely by differences between the procedures. Although laboratory methods are widely used to estimate ruminal degradation, these techniques did not provide comparable estimates of ruminal degradation of barley.

scholarly journals Obtaining Cocrystals by Reaction Crystallization Method: Pharmaceutical Applications

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 898
Author(s):  
Isabela Fanelli Barreto Biscaia ◽  
Samantha Nascimento Gomes ◽  
Larissa Sakis Bernardi ◽  
Paulo Renato Oliveira
Keyword(s):  
Large Scale ◽  
In Vitro Dissolution ◽  
Supersaturated Solution ◽  
Scale Production ◽  
In Situ Techniques ◽  
Crystallization Method ◽  
Large Scale Production ◽  
Poorly Soluble

Cocrystals have gained attention in the pharmaceutical industry due to their ability to improve solubility, stability, in vitro dissolution rate, and bioavailability of poorly soluble drugs. Conceptually, cocrystals are multicomponent solids that contain two or more neutral molecules in stoichiometric amounts within the same crystal lattice. There are several techniques for obtaining cocrystals described in the literature; however, the focus of this article is the Reaction Crystallization Method (RCM). This method is based on the generation of a supersaturated solution with respect to the cocrystal, while this same solution is saturated or unsaturated with respect to the components of the cocrystal individually. The advantages of the RCM compared with other cocrystallization techniques include the ability to form cocrystals without crystallization of individual components, applicability to the development of in situ techniques for the screening of high quality cocrystals, possibility of large-scale production, and lower cost in both time and materials. An increasing number of scientific studies have demonstrated the use of RCM to synthesize cocrystals, mainly for drugs belonging to class II of the Biopharmaceutics Classification System. The promising results obtained by RCM have demonstrated the applicability of the method for obtaining pharmaceutical cocrystals that improve the biopharmaceutical characteristics of drugs.

Autonomic actions of cocaine

1989 ◽  
Vol 67 (9) ◽  
pp. 1168-1176 ◽  
Author(s):  
D. K. Pitts ◽  
J. Marwah
Keyword(s):  
Nervous System ◽  
Autonomic Nervous System ◽  
Adrenergic Receptor ◽  
Monoamine Neurotransmitter ◽  
Autonomic Nervous ◽  
In Situ Techniques ◽  
Receptor Sites ◽  
The Impact

The development of our knowledge of the physiological, pharmacological, and biochemical actions of cocaine has in essence occurred in parallel with the development of our knowledge about the function of the autonomic nervous system. Cocaine is a sympathomimetic compound with potent local anesthetic properties. The principal hypothesis accepted to date to explain the sympathomimetic effects of cocaine is that this drug inhibits neuronal monoamine neurotransmitter reuptake by binding to a transporter or uptake site thereby increasing the effective concentration of neurotransmitter at adrenergic receptor sites. Much of the available evidence for this hypothesis has come from studies utilizing in vitro or in situ techniques. There have been relatively fewer studies examining the impact of cocaine on the autonomic nervous system in the intact animal. In addition, few studies have examined the effects of cocaine on central autonomic function. Past studies concerning the mechanism of action of cocaine are reviewed and recent data addressing the cardiovascular, respiratory, and central autonomic effects of cocaine are discussed.Key words: cocaine, autonomic nervous system.

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