Search results for " Biomedical"
showing 10 items of 480 documents
Effect of water-jet flossing on surface roughness and color stability of dental resin-based composites.
2019
Background The purpose of this in vitro study was to investigate the effects of water-jet flossing on the color stability and surface roughness of five resin-based composites. Material and methods Five commercially available composite resins were studied. Nine disc-shaped specimens (6x2mm) were fabricated from each composite. The specimens were randomly allocated into three groups and three different treatments were performed on each group: storage in water (control group), water-jet flossing using 50 Psi water pressure, and water-jet flossing using 100 Psi water pressure. The water-jet flossing was performed in a standardized manner using a Waterpik® Aquarius® water flosser. Color and roug…
An Inverse Thermogelling Bioink Based on an ABA-Type Poly(2-oxazoline) Amphiphile
2021
Hydrogels are key components in several biomedical research areas such as drug delivery, tissue engineering, and biofabrication. Here, a novel ABA-type triblock copolymer comprising poly(2-methyl-2-oxazoline) as the hydrophilic A blocks and poly(2-phenethyl-2-oxazoline) as the aromatic and hydrophobic B block is introduced. Above the critical micelle concentration, the polymer self-assembles into small spherical polymer micelles with a hydrodynamic radius of approx 8-8.5 nm. Interestingly, this specific combination of hydrophilic and hydrophobic aromatic moieties leads to rapid thermoresponsive inverse gelation at polymer concentrations above a critical gelation concentration (20 wt %) into…
Effects of the cycling workload on core and local skin temperatures
2016
[EN] Purpose: The aim of the study was to determine the influence of cycling workload on the variation of core and skin temperature of the different body regions, and the relationship between both temperature variables. Method: Fourteen cyclists performed two 45-min cycling tests at 35% and 50% of peak power output on different days. The cadence was constant in both tests (90 rpm). Core temperature was measured continuously throughout the test and local skin temperature was recorded before, immediately after and 10 min after finishing the cycling test. Differences in variation of the core and skin temperature and in the effort perception and body mass loss due to different cycling workload …
Production and Characterization of Oxyhydroxyapatites
2018
The amount and alignment of hydroxyl ions influence the bioactivity of hydroxyapatite. Hydroxyl ions in hydroxyapatite are the most mobile and upon heating are the first to leave the lattice to form oxyhydroxyapatite. This work describes a method for producing hydroxyapatite with different amounts of hydroxyl ions, and reports on the changes in Fourier transform infrared absorption at increasing level of dehydroxylation. Detailed analysis of spectra in the 500 – 700 cm-1 range showed a peak shift for the hydroxyl ion absorption line at 632 cm-1 to 637 cm-1 and an increase in the wavenumber for the phosphate line at 575 cm-1.
A mechanistic model on the role of “radially-running” collagen fibers on dissection properties of human ascending thoracic aorta.
2014
Aortic dissection (AoD) is a common condition that often leads to life-threatening cardiovascular emergency. From a biomechanics viewpoint, AoD involves failure of load-bearing microstructural components of the aortic wall, mainly elastin and collagen fibers. Delamination strength of the aortic wall depends on the load-bearing capacity and local micro-architecture of these fibers, which may vary with age, disease and aortic location. Therefore, quantifying the role of fiber micro-architecture on the delamination strength of the aortic wall may lead to improved understanding of AoD. We present an experimentally-driven modeling paradigm towards this goal. Specifically, we utilize collagen fib…
Blend scaffolds with polyaspartamide/polyester structure fabricated via TIPS and their RGDC functionalization to promote osteoblast adhesion and prol…
2019
Target of this work was to prepare a RGDC functionalized hybrid biomaterial via TIPS technique to achieve a more efficient control of osteoblast adhesion and diffusion on the three-dimensional (3D) scaffolds. Starting from a crystalline poly(l-lactic acid) (PLLA) and an amorphous alpha,beta-poly(N-2-hydroxyethyl) (2-aminoethylcarbamate)-d,l-aspartamide-graft-polylactic acid (PHEA-EDA-g-PLA) copolymer, blend scaffolds were characterized by an appropriate porosity and pore interconnection. The PHEA-EDA-PLA interpenetration with PLLA improved hydrolytic susceptibility of hybrid scaffolds. The presence of free amino groups on scaffolds allowed to tether the cyclic RGD peptide (RGDC) via Michael…
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 different polishing techniques on surface roughness and bacterial adhesion of three glass ionomer-based restorative materials : in vitro st…
2020
Background Although many reports concluded that polishing of glass ionomers is crucial for smoother surface and limiting the adhesion of cariogenic bacteria, there is no specific surface treatment protocol recommended. A novel material in the same category was released recently claimed to have surface smoothness comparable to resin composite and bacterial adhesion less than other types of glass ionomers. In this study, different polishing systems were tested with three glass ionomers one of them is the novel material to find the most appropriate polishing protocol. Objectives: To evaluate and compare the surface roughness and bacterial adhesion to resin modified glass ionomer, bioactive ion…
Effects of three different bleaching agents on microhardness and roughness of composite sample surfaces finished with different polishing techniques
2017
BACKGROUND The aim of this study was to evaluate effects of different polishing methods and whitening agents on surface hardness and roughness of nano-hybrid composite resin. MATERIAL AND METHODS In total, one hundred twenty disc-shaped specimens were prepared to nano-hybrid composite (Charisma Diamond). 60 samples were used for microhardness measurements and the others were used for the evaluation of surface roughness. Samples were divided randomly into two subgroups (n = 30 each). In first group a low-viscosity liquid polishing agent (Biscover LV) was applied. In the second group, nothing was applied. All the samples were stored in distilled water at 37°C for 24 h. After initial measureme…
Efficacy of three methods for inserting calcium hydroxide-based paste in root canals
2017
BACKGROUND: To compare the quality of calcium hydroxide paste fillings performed by three different techniques. MATERIAL AND METHODS: Sixty extracted maxillary central incisors, with previous root canal treatment, were decoronated and the gutta-percha was completely removed from the root canals. Subsequently, the canals were filled with a calcium hydroxide-based paste composed of calcium hydroxide, bismuth carbonate, and glycerin. The study samples were divided into the following three groups on the basis of three insertion techniques (n = 20, each): conventional technique using a hand instrument (MAN), rotary Lentulo spiral (LEN) technique, and a combined technique combining conventional h…