Aim: To evaluate the effect of two bonding systems and two curing systems on sealing ability of class V composite restorative materials. Materials and methods: This study was performed in vitro on 40 caries free upper first premolar teeth. The Standardized class V cavity preparation on buccal and lin- gual surfaces of each tooth was done. Then the teeth were randomly divided into two major groups each of twenty. 40 cavities were performed on these teeth and the first group7th generation bonding agent (i Bond) were applied according to the manufacturer instructions and single increment of univer- sal composite (XRV Herculite) from kerr were applied and twenty of the cavities were cured with con- ventional light cure device (astralis-5) and the other twenty cavities were cured with a LED. While the second group 5th generation (Excite bonding agent) applied according to the manufacturer instructions. And filled with universal composite (tetric).Twenty of the cavities light cured with conventional light cure device and the other twenty cavities cured with LED light cured device. Then the teeth were stored in normal physiological saline in an incubator at (37Co) half of each sub group (10 cavities) were stored for one day and the second half stored for one week. Then the teeth were thermo cycled for (200) cycles, after thermo cycling all teeth were immersed in a freshly prepared solution of 2% methylene blue for (24) hours at (37Co). Results: The results showed that there was no statistically significant difference between samples cured using conventional light curing system and those cured using LED light curing system. The type of bonding system and composite material used in this study had no sig- nificant effect on reducing microleakage. Samples aged for seven days produced significantly higher levels of microleakage than that for one day. Conclusions: All samples in this study showed microlea- kage with different levels. Microleakage increases as the age increases. Neither the types of light curing system nor the types of bonding were able to reduce microleakage.
The limited availability of the two-circle diffractometer to collect intensity measurements down to the monoclinic system has been extended in a novel procedure to collect intensities for the triclinic system. The procedure involves the derivation of matrix elements from graphical representation of the reciprocal lattice. Offset of the origins of the upper layers from that of the zero-layer - characteristic of triclinic system - is determined and the 3 x 3 matrix elements are evaluated accordingly. Details of crystal alignment by X-rays for the triclinic system utilizing the intensities of equivalent reflections is described
Sheets of Epoxy (EP) resin with addition of TiO2 of grain size (1.5μm, and 50nm) and weight percentage (1%, 3%, and 5%) were prepared. Discs of 20mm diameter and 3mm thickness were cut for dielectric measurements. Dielectric properties (dielectric constant, dispassion factor and electrical conductivity) over the frequency range 102 -106 Hz were measured.
Comparison was made between the effect of micro and nano particles of TiO2 on the dielectric properties of EP composites with different weight percentage. Epoxy composites with micro sized particles of TiO2 were observed to have the better values of dielectric properties.
In the present research, the chemical washing method has been selected using three chelating agents: citric acid, acetic acid and Ethylene Diamine Tetraacetic Acid (EDTA) to remove 137Cs from two different contaminated soil samples were classified as fine and coarse grained. The factors that affecting removal efficiency such as type of soil, mixing ratio and molarity have been investigated. The results revealed that no correlation relation was found between removal efficiency and the studied factors. The results also showed that conventional chemical washing method was not effective in removing 137Cs and that there are further studies still need to achieve this objective.
This is a contribution to study the dwelling of two previous cases of kala azar in the endemic area. In order to assess the possible ecological causes of the incidence and the prevalence of visceral leishmaniasis in central Iraq.
The aim of this study to identify the effect of using two strategies for active learning ( Jigsaw Strategy & Problems Solving) in learning some balanced beam's skills in artistic gymnastics for women , as well as to identify the best of the three methods (jigsaw strategy , problems solving and the traditional method) in learning some skills balance beam , the research has used the experimental methodology, and the subject included the students of the college of Physical Education and Sports Sciences / University of Baghdad / third grade and by the lot was selected (10) students for each group of groups Search three and The statistical package for social sciences (SPSS) was used means, the standard deviation and the (T.test), the one way a n
... Show MoreThe paper presents an investigation to the flutter speed of composite wing for different ply orientation. Structurally the composite wing was idealized as a composite beam load carrying structure. Theodorsen’s expression was used to get the 2- dimension unsteady lifting force and pitching moment in the limit of incompressible flow and subsonic speed which were integrated over the wing span. A free vibration analysis was first carried out to get the natural frequencies and mode shapes .The velocity-damping (V-g) method was used to calculate the flutter speed and the flutter frequency. A wing of unmanned aerial vehicle was manufactured from woven glass and polyester resin where the flutter speed was calculated experimentally by the wind
... Show MoreBackground: This study was performed to determine the effect of aging of different types of composite material restorations on: Shear bond strength (SBS) to light cure and no mix chemical cure orthodontic adhesives with sapphire bracket and the debonding failure sites. Materials and methods: One hundred forty four composite disks were made from three different composite resin materials which are: 3M Filtek Z250, 3M filtek Z350 and 3M Valux plus, each group with (48) disks each, then according to the duration of storage each group was subdivided into two equal groups one of them stored for one day and the other was stored for one month, then each group was further subdivided into two equal subgroups with (12) disks each one bonded with ligh
... Show MoreThis study was performed by using the unsaturated polyester resin as matrix to the
composite materials with the rice husk as reinforced materials . The research included study
of wear test on the composite material The results show that the, wear is increased with the
increase of applied load and distance slipping and also with time increase . moreover the
shows that the higher value wear rate( 1.91gm/cm) from the load (20) N and the higher value
wear rate (1.43gm/cm) from the higher distance (4cm) and from the higher time (6min) higher
wear rate (5.33gm/cm).
In this paper the effect of mixing TiO2 nanoparticles with epoxy resin is studied. The TiO2 nanoparticles would be synthesis and characterized by scanning electron microscopy (SEM), XRD FTIR, for two particle sizes of 50 and 25 nm. The thermal conductivity is measured with and without composite epoxy resin; the results showed that the thermal conductivity was increased as nanoparticle concentration increased too. The thermal conductivity was increased as particle size decreased.
The research aims to find approximate solutions for two dimensions Fredholm linear integral equation. Using the two-variables of the Bernstein polynomials we find a solution to the approximate linear integral equation of the type two dimensions. Two examples have been discussed in detail.