Background: This study evaluated the influence of different fiber formulations incorporation in resin composite on cuspal deflection (CD) of endodontically-treated teeth with mesio-occluso-distal (MOD) cavities. Materials and Methods: Thirty-two freshly extracted maxillary premolar teeth received MOD cavity preparation followed by endodontic treatment using single cone obturation technique, and divided into: Group I: direct composite resin only using a centripetal technique, Group II: direct composite resin with short fiber-reinforced composite (everX Flow), Group III: direct composite resin with leno wave ultra-high molecular weight polyethylene (LWUHMWPE) fibers placed on the cavity floor, and Group IV: direct composite resin with LWUHMWPE fibers placed circumferentially around the cavity walls (wallpapering technique). The CD was measured using a novel digital evaluation method, whereby each tooth was scanned by a desktop scanner (Medit T710) at three different time intervals: before and after cavity preparation, and after restoration. The intercuspal distance (ICD) was measured digitally in μm at each interval using Medit compare metrology software, followed by measurement of the CD by subtracting the ICD after cavity preparation; and after restoration from the before preparation one to obtain the “after cavity preparation CD1” and “the after restoration CD2”, respectively. The data were analyzed using one-way ANOVA and Tukey HSD tests at a significance level of 0.05. Results: The highest CD was recorded in Group I with statistically significant differences with all other groups (P<0.05). No statistically significant differences were found between the other groups (Groups II, III, and IV) (P>0.05). Conclusions: There was an inward deflection of the cusps in all groups following cavity preparation and restoration as elicited by the negative CD1 and CD2 values. The incorporation of fibers, regardless of their type or orientation, resulted in a significant reduction in CD of endodontically treated premolar teeth as compared with those restored with resin composite alone.
Objective: Evaluate the effects of different storage periods on flexural strength (FS) and degree of conversion (DC) of Bis-Acryl composite and Urethane dimethacrylate provisional restorative materials. Material and Methods: A total of 60 specimens were prepared from four temporary crown materials commercially available and assigned to four tested groups (n = 15 for each group): Prevision Temp, B&E CROWN, Primma Art, and Charm Temp groups. The specimens were stored in artificial saliva, and the FS was tested after 24 h, 7 d, and 14 d. A standard three-point bending test was conducted using a universal testing machine. Additionally, the DC was determined using a Fourier transform infrared spectroscopy (FTIR) device. The data were analyzed st
... Show MoreThe aim of this investigation is to evaluate the experimental and numerical effectiveness of a new kind of composite column by using Glass Fiber‐Reinforced Polymer (GFRP) I‐section as well as steel I‐section in comparison to the typical reinforced concrete one. The experimental part included testing six composite columns categorized into two groups according to the slenderness ratio and tested under concentric axial load. Each group contains three specimens with the same dimensions and length, while different cross‐section configurations were used. Columns with reinforced concrete cross‐section (reference column), encased GFRP I‐section, and encased steel I‐section were adopted in each
In this work, an optical fiber biomedical sensor for detecting the ratio of the hemoglobin in the blood is presented. A surface plasmon resonance (SPR)-based coreless optical fiber was developed and implemented using single- and multi-mode optical fibers. The sensor is also utilized to evaluate refractive indices and concentrations of hemoglobin in blood samples, with 40 nm thickness of (20 nm Au and 20 nm Ag) to increase the sensitivity. It is found in practice that when the sensitive refractive index increases, the resonant wavelength increases due to the decrease in energy.
This study deals with the serviceability of reinforced concrete solid and perforated rafters with openings of different shapes and sizes based on an experimental study that includes 12 post-fire non-prismatic reinforced concrete beams (solid and perforated). Three groups were formed based on heating temperature (room temperature, 400 °C, and 700 °C), each group consisting of four rafters (solid, rafters with 6 and 8 trapezoidal openings, and rafter with eight circular openings) under static loading. A developed unified calculation technique for deflection and crack widths under static loading at the service stage has been provided, which comprises non-prismatic beams with or without opening exposed to flexure concentra
... Show MorePurpose: To compare the antibacterial-enhancing efficacy of aloe vera and honey in salicylic acid topical formulations against acne. Method: Six formulations containing 5 % salicylic acid were developed as creams and gels as follows: Formulations S, V and H were creams containing salicylic acid alone (S), salicylic acid with 28 % aloe vera (V), and salicylic acid with 10 % honey (H). Formulations J, M, and B were gels containing salicylic acid alone (J), salicylic acid with aloe vera 20 % (M) and salicylic acid with 12 % honey (B). Each formula was evaluated for colour, odour, pH, viscosity, spreadability, and stability under different temperatures (25, 30, and 60oC) and times (1 hour, 1 day, and 1 week). Furthermore, antibacterial
... Show MoreChromatographic and spectrophotometric methods for the estimation of mebendazole in
pharmaceutical products were developed. The flow injection method was based on the oxidation of
mebendazole by a known excess of sodium hypochlorite at pH=9.5. The excess sodium hypochlorite is then
reacted with chloranilic acid (CAA) to bleach out its color. The absorbance of the excess CAA was recorded
at 530 nm. The method is fast, simple, selective, and sensitive. The chromatographic method was carried out
on a Varian C18 column. The mobile phase was a mixture of acetonitrile (ACN), methanol (MeOH), water
and triethylamine (TEA), (56% ACN, 20% MeOH, 23.5% H2O, 0.5% TEA, v/v), adjusted to pH = 3.0 with
1.0 M hy
This paper reports a.c., d.c. conductivity and dielectric behavior of Ep-hybrid composite with12 Vol.% Kevlar-Carbon hybrid . D.C. conductivity measurements are conducted on the graded composites by using an electrometer over the temperature range from (293-413) K. It was shown then that conductivity increases by increasing number of Kevlar –Carbon fiber layers (Ep1, Ep2, Ep3), due to the high electrical conductivity of Carbon fiber. To identify the mechanism governing the conduction, the activation energies at low temperature region (LTR) and at high temperature region (HTR) have been calculated. The activation energy values for hybrid composite decrease with increasing number of fiber layers. The a.c. conductivity was measured over fr
... Show MoreA new hetrocyclic liquid crystal compounds containing 1,3,4-oxadiazole with different substituted in para position (Bromo, Chloro, Nitro and Methyl) were synthesized and characterized by melting points, FTIR Spectroscopy and 1HNMR spectroscopy for [Cl-SR6] and [NO2-SR6] compounds. The liquid crystalline properties of the synthesized compounds were studied by using hot-stage polarizing optical microscopy (POM), so they determined the transition enthalpies and entropies by using differential scanning calorimetery (DSC). All of the compounds show mesomorphic properties. The compounds [Br-SR6], [Cl-SR6] and [NO2SR6] exhibit an enantiotropic dimorphism smectic (Sm) phase, while the compounds [MeSR6] showed nematic (N) phase throw cooli
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