Background: Maxillary first premolar with wide MOD cavity more susceptible to fracture. The aim of this study was to assess the influence of cavity design for cusp coverage on the fracture resistance of weakened maxillary first premolar restored with CAD/CAM hybrid ceramic versus nanohybide composite. Materials and Methods: Fifty six intact maxillary first premolars of approximately comparable sizes were divided into seven groups eight for each: Group A: Intact teeth (control group); Group B: teeth prepared for MOD inlay; Group C: teeth prepared for MOD onlay covering the lingual cusp; Group D: teeth prepared for MOD covering buccal and lingual cusps ,the previous three groups indirectly restored with nanohybrid composite (3M ESPE Z 250 XT); Group E,F,G prepared with the same design as group B, C, D respectively and restored with CAD/CAM hybrid ceramic (VITA ENAMIC). Results: An axial compression test was used to measure the fracture strength of experimented teeth. The readings were analyzed statistically by t-test, one way ANOVA and LSD, then the mode of fracture had been examined. The results showed that sound teeth in group (A) had more fracture resistance values than all experimental groups and the difference were highly significant with group (B, E, F, G).When the influence of cavity design tested among composite groups it showed highly significant difference between group (B) and (C)and the highest fracture resistance value was for group(C), whereas the influence of cavity design among Enamic groups showed highly significant difference between group (E) and (G) the highest fracture resistance value was for group(E).T-test between similar designs showed non-significant difference between MOD groups and highly difference between other groups. Conclusions: Cusp coverage increased the fracture resistance of composite groups but result in non-restorable fracture, while Enamic total onlay presented promising fracture resistance with favorable mode of fracture. Key words: Fracture resistance, CAD/CAM, hybrid ceramic, VITA ENAMIC, nanohybrid composite, cusp coverage.
As tight gas reservoirs (TGRs) become more significant to the future of the gas industry, investigation into the best methods for the evaluation of field performance is critical. While hydraulic fractured well in TRGs are proven to be most viable options for economic recovery of gas, the interpretation of pressure transient or well test data from hydraulic fractured well in TGRs for the accurate estimation of important reservoirs and fracture properties (e.g. fracture length, fracture conductivity, skin and reservoir permeability) is rather very complex and difficult because of the existence of multiple flow profiles/regimes. The flow regimes are complex in TGRs due to the large hydraulic fractures n
Introduction: The use of screw-retained hybrid arch bars (HABs) is a relatively recent development in the treatment of mandibular fractures. The purpose of this study is to compare the clinical outcome between HAB and the conventional Erich arch bar (EAB) in the closed treatment of mandibular fractures. Materials and methods: This study included 18 patients who were treated for mandibular fractures with maxillomandibular fixation (MMF), patients were randomly assigned into a control group (n = 10) in which EAB was used and study group (n = 8) in which HAB was used. The outcome variables were time required for application and removal, gingival inflammation scores, postoperative complications, and incidence of wire-stick injury or gloves perf
... Show MoreThe monogenean Gyrodactylus taimeni Ergens, 1971 was recorded in this study for the first time in Iraq from gills of the common carp Cyprinus carpio Linnaeus, 1758. The description and measurements of this parasite as well as illustration were given. In addition, a list of species of Gyrodactylus so far recorded from C. carpio in Iraq is also included together with a list of all other hosts recorded for each gyrodactylid species.
In this work, a ceramic model has obtained from Iraqi bentonite as a base material with limited additions of alumina and silica. The selected material can bear temperatures higher than the bearing temperature of bentonite as it achieved tolerance temperatures (1300°C) based on X-ray diffraction patterns. It was found that the addition of alumina and silica led to the occurrence of basic phases such as mullite, quartz, cordierite and feldspar in percentages that depended on the percentage of addition in the mixture and the firing temperature, which was (1000-1300)°C.
The present experimental work is conducted to examine the influence of adding Alumina (Al2O3) nanoparticles and Titanium oxide (TiO2) nanoparticles each alone to diesel fuel on the characteristic of the emissions. The size of both Alumina and Titanium oxide nanoparticles which have been added to diesel fuel to obtain nano-fuel is about 20 nm and 25 nm respectively. Three doses of (Al2O3) and (TiO2) were prepared (25, 50, and 100) ppm. The nanoparticles mixed with gas oil fuel by mechanical homogenous (manual electrical mixer) and ultrasonic processor. The study reveals that the adding of Aluminum oxide (Al2O3) and Titanium oxide (TiO2) to g
... Show MoreBackground: The skull offers a high resistance of adverse environmental conditions over time, resulting in the greater stability of the dimorphic features as compared to other skeletal bony pieces. Sex determination of human skeletal considered an initial step in its identification. The present study is undertaken to evaluate the validity of 3D reconstructed computed tomographic images in sex differentiation by using craniometrical measurements at various parts of the skull. Materials and Method: 3D reconstructed computed tomographic scanning of 100 Iraqi subject, (50 males and 50 females) were analyzed with their age range from20-70 years old. Craniometrical linear measurements were located and marked on both side of the 3D skull images.
... Show MoreThe effect of different cutting fluids on surface roughness of brass alloy workpiece during turning operation was carried out in this research. This was performed with different cutting speed, while other cutting parameters had been regarded as constants(feeding rate , and depth of cut). Surface roughness of machined parts that will be tested by electronic surface roughness tester .The results show that the standard coolant gives the best values of surface roughness for fixed cutting speed ,followed by sun flower oil that has approximately the same effect, while the air stream as a coolant gave unsatisfied results for the evaluation of surface roughness.
In the other hand the best values of surface roughness were recorded for max
... Show MoreThis study aims to investigate the effect of changing skins material on the strength of sandwich plates with circular hole when subjected to mechanical loads. Theoretical, numerical and experimental analyses are done for sandwich plates with hole and with two face sheet materials. Theoretical analysis is performed by using sandwich plate theory which depends on the first order shear deformation theory for plates subjected to tension and bending separately. Finite element method was used to analyse numerically all cases by ANSYS program.
The sandwich plates were investigated experimentally under bending and buckling load separately. The relationship between stresses and the ratio of hole diameter to plate width (d/b) are built, by
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