Background: Esthetic correction represents one of the clinical conditions that required the use of laminate veneers in premolars region. Aim of the study: The purpose of this study was to evaluate the fracture strength of the laminate veneers in maxillary first premolars, fabricated from either composite (direct and indirect techniques) or ceramic CAD/CAM blocks. Materials and Methods: Fifty sound human maxillary premolar teeth were used in this in vitro study. Teeth were divided randomly into one control group and four experimental groups of ten teeth each; Group A: Restored with direct composite veneer (Filtek Z250 XT), Group B: Restored with indirect composite veneers (Filtek Z250 XT), Group C: Restored with lithium disilicate ceramic CAD/CAM blocks (IPS e. max CAD) and Group D: Restored with resin nano ceramic CAD/CAM blocks (Lava Ultimate Restorative). Standard preparations were done using Ceramic Veneer Set (Komet). Indirect laminate veneers were cemented with the Relyx Veneer Cement (3M ESPE) and all specimens were stored in distilled water at 37°C for 2 weeks. The load was applied on the occlusal part of the veneer at 45˚ to long axis of the tooth using universal testing machine. Results were analyzed with one-way ANOVA and LSD tests. Specimens were examined by stereomicroscope at a magnification of 20x to evaluate the mode of failure. Results: Control group showed higher mean of fracture strength with highly significant difference in comparison to the experimental groups (P<0.01). (Group A) showed higher mean of fracture strength with statistically significant difference in comparison to (Group B and Group D). On the other hand the difference between (Group A and Group C) was statistically highly significant. Statistically non-significant difference was found among the three indirectly restored groups. Conclusions: All veneers used in this study can be considered as acceptable treatment in the premolars region for patients with normal biting force. Direct composite veneer is the most favorable technique in term of fracture strength, while IPS e. max CAD laminate veneers were least likely to fracture and most likely to completely debond.
In this study the design and installation of evaporative air cooler was carried out using completely outdoor air (fresh air) according to two stage evaporative cooling principle. The laboratory equipment was installed by designing and manufacturing a cross flow plate heat exchanger, where aluminum plates used for this purpose with dimensions (50 × 30 × 40 cm). The surfaces of heat exchanger were covered by sawdust from wetted channels side, to increase the percentage of wetting these surfaces and hence improve the performance and efficiency of air cooler.
An experimental study was carried out to estimate the performance of cooling system, where som
... Show MoreTRIPS agreement was The first to apply protection by patents. However, this type of protection, which grants exclusive and monopoly rights to patent owners, came at the expense of developing countries which are considered rich in biodiversity and also at the expense of traditional and poor knowledge of modern technologies. The release of new plant varieties has led to the emergence of biopiracy and looting of the rights of developing countries without a license
Registration techniques are still considered challenging tasks to remote sensing users, especially after enormous increase in the volume of remotely sensed data being acquired by an ever-growing number of earth observation sensors. This surge in use mandates the development of accurate and robust registration procedures that can handle these data with varying geometric and radiometric properties. This paper aims to develop the traditional registration scenarios to reduce discrepancies between registered datasets in two dimensions (2D) space for remote sensing images. This is achieved by designing a computer program written in Visual Basic language following two main stages: The first stage is a traditional registration p
... Show MoreAbstract
health organizations are trying to introduce services of high quality and efficiency which requires applying some standards of nursing career to improve nursing service quality in the hospital, which provides an essential data base key to diagnosis the negative and positive part in nursing services to guarantee the quality of services presented . The aim of this study is to evaluated the quality of nursing service through stating the indicators of nursing career standards by comparing the reality of the a hospital with what should standards . In addition , adapting nursing career standards with what is suitable for hos
... Show MorePrediction of the structural response of reinforced concrete to the time-dependent, creep and shrinkage, volume changes is complex. Creep is usually determined by measuring the change, with time, in the strain of specimens subjected to a constant stress and stored under appropriate conditions. This paper brings into view the development of creep strain for four self-compacting concrete mixes: A40, AL40, B60 and BL60 (where 40 and 60 represent the compressive strength level at 28 days and L indicates to Portlandlimestone cement). Specimens were put under sustained load and exposed to controlled conditions in a creep chamber (ASTM C512). The test results showed that normal strength Portland-limestone mixes have yielded lower ultimate c
... Show MoreConstruction projects are complicated in nature and require many considerations in contractor selection. One of the complicated interactions is that between performance with the project size, and contractor financial status, and size of projects contracted. At the prequalification stage, the financial requirements restrict the contractors to meet minimum limits in financial criteria such as net worth, working capital and annual turnover, etc. In construction projects, however, there are cases when contractors meet these requirements but show low performance in practice. The model used in the study predicts the performance by training of a neural network. The data used in the study are 72 of the most recent roadw
... Show MoreThe study focused on the identification of the natural relation between the organizational components, and the most important is the organizational structure, which not hid its effect on each function and operation of the organizational structure through commanding the individual craters and its forms according to the requirement of these function, also it has relation with an organic synthesis that between the dimensions of the organic synthesis and the practice side in the commission of Integrity.
The problem of the research pensioned in some questions about hypothesis and theoretical parts, in which they go a mention about the hypothesis questions is to use all the knowledge's in this atmosphere and th
... Show MoreThe charge transfer at C23H17F8N8O2PRu, C44H30BF4N5O4Ru, C56H52CL5N5OOsP2 and C76H88F80N24O11P10Ru4 nitrosyl complexes are investigation and studies theoretically using the quantum consideration. Charge transfer behavior largely rely to the electric properties of nitrosyl complexes system whose depending on the main important parameters for the transmission rate constant such that: orientation transition energy, overlapping coupling coefficient, driving force energy, height barrier and Temperature T (K). Data results have been evaluated using a MATLAB program. Results show that rate of charge transfer increases due to increases the orientation transition energy.