Objectives To tailor composites of polyethylene–hydroxyapatite to function as a new intracanal post for the restoration of endodontically treated teeth (ETT). Methods Silanated hydroxyapatite (HA) and zirconium dioxide (ZrO2) filled low-density polyethylene (LDPE) composites were fabricated by a melt extrusion process and characterised using infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The flexural strength and modulus were determined in dry state and post ageing in simulated body fluid and fractured surfaces analysed by SEM. The water uptake and radiographic appearance of the experimental composites were also measured and compared with a commercially known endodontic fibre post. Data were submitted to one-way analysis of variance (ANOVA) and post hoc Tukey multiple comparison tests at a level of significance P < 0.05. Results The LDPE/HA composites were structurally flexible and the HA content had a significant effect on the flexural strength and modulus. A univariate analysis of variance showed no significant differences in modulus and strength (P < 0.05) post accelerated ageing in simulated body fluid with very low water uptake. The melting point of the LDPE/HA composites ranged between 135 and 136 °C, which would facilitate removal in case of retreatment using conventional dental heating devices. The inclusion of HA reduced the damping thereby enhancing dimensional stability, whilst the addition of zirconia yielded a semi-translucent material that was sufficiently radiopaque, comparable to commercial posts, thus yielding aesthetic materials. Conclusions Innovative materials for restoration of ETT were developed; offering considerable benefits over the currently available material in terms of biomechanical and thermal properties. Clinical significance This study provided a new option for the development of a new intracanal post made up of functional and aesthetic composites.
The importance of this study stems from the importance of preserving the environment and creating a clean sustainable environment from waste and emissions and all the operations of industrial companies in general and cement companies in particular by activating sustainability accounting standards. The research aims to identify and diagnose deviations in violation of sustainability standards by employing the non-renewable resources standard (NR0401) For the construction industries to create a sustainable audit environment, the deductive approach was followed in the theoretical side and the inductive and descriptive approach to the practical side. The most important results of the research were the possibility of applying sustainab
... Show MoreThe residual limb within the prosthesis, is often subjected to tensile or fatigue stress with varying temperatures. The fatigue stress and temperatures difference which faced by amputee during his daily activities will produces an environmental media for growth of fungi and bacteria in addition to the damage that occurs in the prosthesis which minimizingthe life of the prosthetic limb and causing disconfirm feeling for the amputee.
In this paper, a mechanical and thermal properties of composite materials prosthetic socket made of different lamination for perlon/fiber glass/perlon, are calculated by using tesile test device under varying temperatures ( from 20oC to 60oC), also in this paper a device for measuring rotational bendin
... Show MoreAlternative distribution to estimate the Dose – Response model in bioassay excrement
This research concern to study five different distribution (Probit , Logistic, Arc sine , extreme value , One hit ), to estimate dose –response model by using m.l.e and probit method This is done by determining different weights in each distribution in addition find all particular statistics for vital model .
Experimental tests were carried to control lost circulation in the Khabaz oil field using different types of LCMs including Nano-materials. A closed-loop circulation system was built to simulate the process of lost circulation into formations. Two dolomite plugs were used from different depths of the formation of Azkand in Khabaz oil field. The experimentations were carried out to study the effect of different types of LCMs, cross-linked copolymer (FLOSORB CE 300 S), SiO2 NP, and Fe2O3 NP, on mud volume losses as a function of time.
The rheological measurements of the nanoparticles-reference mud system showed that both of the SiO2 NP and Fe2O3 NP w
... Show MoreObjective:Fluorid-containing dental alginate impression materials can exert a considerable reduction in
enamel solubility. The objective was to evaluate the effect of fluoride addition on the setting time and
compressive strength of alginate impression materials.
Methodology: 60 samples were constructed from alginate impression material (30 samples for setting
time test and 30 samples for compressive strength test).Specimens of each test divided into three
subgroup. Group A: 10 specimens of alginate were mixed with distilled water [control], Group B: 10
specimens of alginate were mixed with100-ppm fluoride and Group C:10 specimens of alginate were
mixed with 2%Naf.
Results: the result of setting time test showed t
The current research is concerned with methods of formation and their effect on the sintering process of ceramic materials. The research is divided into a number of chapters. The first chapter addressed the research structure (the research problem, importance, objective, limits, and it also defined the terms used in the research). The second chapter addressed the theoretical framework, where the theoretical framework has been divided into three sections. The first section dealt with methods of formation of ceramic materials including: Plasticizing method 2- semi-dry pressing method 3- dry pressing method 4- extrusion method 5- casting method.
The researcher found that there is a clear difference between the methods through her formati
The city of Karbala is one of the most important holy places for visitors and pilgrims from the Islamic faith, especially through the Arabian visit, when crowds of millions gather to commemorate the martyrdom of Imam Hussein. Offering services and medical treatments during this time is very important, especially when the crowds head to their destination (the holy shrine of Imam Hussein (a.s)). In recent years, the Arba'in visit has witnessed an obvious growth in the number of participants. The biggest challenge is the health risks, and the preventive measures for both organizers and visitors. Researchers identified various challenges and factors to facilitating the Arba'in visit. The purpose of this research is to deal with the religious an
... Show MoreA linear engine generator with a compact double-acting free piston mechanism allows for full integration of the combustion engine and generator, which provides an alternative chemical-to-electrical energy converter with a higher volumetric power density for the electrification of automobiles, trains, and ships. This paper aims to analyse the performance of the integrated engine with alternative permanent magnet linear tubular electrical machine topologies using a coupled dynamic model in Siemens Simcenter software. Two types of alternative generator configurations are compared, namely long translator-short stator and short translator-long stator linear machines. The dynamic models of the linear engine and linear generator, validated
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