Background: Dental erosion is a common oral condition which results due to consumption of high caloric and low pH acidic food such as carbonated drinks and fruit juices. It is expected that these food types can cause irreversible damage to dental hard tissues and early deterioration of the dental restorations. So, this study aimed to evaluate and compare the erosive potential effects of orange fruit juice and Miranda orange drink on the microhardness of an orthodontic composite material. Materials and methods: Thirty discs with a thickness of 2 mm and a diameter of 10 mm were prepared from orthodontic bonding composite. The prepared discs were equally divided into three groups (n=10). Microhardness analysis was carried out both prior to and subsequent to immersion cycles. The microhardness of the specimens underwent evaluation subsequent to immersion in the beverages for durations of 6 hours (equivalent to one day) and 42 hours (equivalent to seven days). Microhardness measurements at baseline, one day, and one week were performed utilizing the Vickers microhardness testing. Statistical analyses were carried out using repeated measure one way ANOVA test and Bonferroni post-hoc test with a level of significant p< 0.05. Results: The micro hardness of composite exposed to the selected soft drinks was significantly decreased (p< 0.05). Conclusions: Natural, industrial orange juices and Miranda can affect the micro hardness of composite. The beverage effect on the orthodontic composite based on the type of juice and the exposure time to these beverages.
In this research, the methods of Kernel estimator (nonparametric density estimator) were relied upon in estimating the two-response logistic regression, where the comparison was used between the method of Nadaraya-Watson and the method of Local Scoring algorithm, and optimal Smoothing parameter λ was estimated by the methods of Cross-validation and generalized Cross-validation, bandwidth optimal λ has a clear effect in the estimation process. It also has a key role in smoothing the curve as it approaches the real curve, and the goal of using the Kernel estimator is to modify the observations so that we can obtain estimators with characteristics close to the properties of real parameters, and based on medical data for patients with chro
... Show MoreThe field of structural optimization (optimal design) has grown rapidly over the past decades with many different optimization methods that could be used to produce a structure of minimum weight. This research deals with two aspects, in the first, a general numerical technique based on the finite element analysis and it suggests to investigate the preliminary behavior of metal stiffened plate under action of static load environment. The technique was included a finite element model of the structures using high- order isoparimetric plate elements to be used to create a certain models to obtain their optimum design. The models are characterized such that, each model is builded using different types of stiffener configuration. The second as
... Show MoreThis research is concerned with a new type of ferrocement characterized by its lower density and enhanced thermal insulation. Lightweight ferrocement plates have many advantages, low weight, low cost, thermal insulation, environmental conservation. This work contain two group experimental : first different of layer ferrocement, second different of ratio aggregate to cement. The experiments were made to determined the optimum proportion of cement and lightweight aggregate (recycle thermestone ). A low W/C ratio of 0.4 was used with super plasticizer conforming to ASTM 494 Type G. The compressive strength of the mortar mixes is 20-25 MPa. The work also involved the determination of thermal properties .Thermal conductivity value of thi
... Show Morethe research ptesents a proposed method to compare or determine the linear equivalence of the key-stream from linear or nonlinear key-stream
Background: The aim of this study was to evaluate the push-out bond strength of four different obturation materials to intraradicular dentin and to determine the failure mode. Materials and method: forty straight palatal roots of the maxillary first molars teeth were used in this study, the roots were instrumented using crown down technique and rotary EndoSequence system, the roots were randomly divided into four groups according to the materials used for obturation (n=10).Group (1): AH Plus sealer and gutta-percha. Group (2): Activ GP glass ionomer sealer and Activ GP gutta-percha (Activ GP system). Group (3): Bioceramic sealer and Bioceramic gutta-percha. Group (4): GuttaFlow2 sealer and gutta-percha. For all groups single cone obturatio
... Show MoreOrganic light emitting diodes (OLEDs) were fabricated containing host molecule of conjugated polymer MEH-PPV poly (2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenlenevinylene) which was dissolved in chloroform solvent and doped with guest molecules MWCNTs that were dissolved in DMF solvent with different volume ratios 0.05 and 0.15, nanocomposite system which acts as active layer in OLEDs device. The Poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) "PEDOT:PSS" and Tris98-hydroxyquinoline) aluminum "Alq3" as hole transport layer HTL and electron transport layer ETL were used respectively, to enhanced the injection charge from the electrodes to the active layer. Spin coating method used for achieving facile and low cost OLED. The absorption s
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