Background: The marginal adaptation has a key role in the success and longevity of the fixed dental restoration, which is affected by the impression and the fabrication techniques .The objective of this in vitro study was to evaluate and compare the marginal fitness of lithium disilicate crowns using two different digital impression techniques (direct and indirect techniques) and two different fabrication techniques (CAD/CAM and Press techniques). Materials and Methods: Thirty two sound upper first premolar teeth of comparable size extracted for orthodontic reason were selected in this study .Standardized preparation of all teeth samples were carried out with modified dental surveyor to receive all ceramic crown restoration with 1 mm deep chamfer finishing line, 4 mm axial length and 6 degree convergence angle. Half of the teeth were duplicated and poured in type IV dental stone to have sixteen dies and then these dies and the remaining teeth divided in to two groups according to the type of digital impression techniques (n=16) as follow: Group A: Indirect digital impression technique scanned by inEos X5 camera; Group B: Direct digital impression technique scanned by CEREC AC Omnicam camera. Each group was subdivided according to the technique of fabrication into two subgroups (n=8): Press technique using IPS e-max press (A1, B1); CAD/CAM technique using IPS e-max CAD (A2, B2).Marginal gaps were evaluated on the prepared teeth at four defined points on each aspect using digital microscope at a magnification of (280X). One way ANOVA and LSD tests were used to identify and localize the source of difference among the groups. Results: The results showed that indirect digital impression with IPS e-max CAD/CAM group A2 revealed the poorest marginal integrity with (55.93 μm ± 3.300). Group B2 and group A1 were next in line with(44.49 μm ± 6.840 and 37.74 μm± 5.433) respectively, while in the first group of restorations, the result of 29.9 μm ± 5.534 obtained with direct digital impression with pressable ceramic was clearly better. Conclusions: All the tested digital impression techniques showed clinically acceptable accuracy and intraoral scanning with pressable ceramic significantly enhanced the marginal fit
The effect of White Place Image ( Test Image ) A4 has been studied as a function of luminous intensity using the t tu un ng gs st te en n l la am mpp and web camera enet. It was found that the tungsten lamp gives almost even intensities for the three color band and lighting composite at low voltage .while at high voltage causes a fare from each other . The statistical characteristic(mean and stander deviation ) results for three colors composites RGB and lighting composites L showed that the mean and stander deviation increases with the increase of voltage possibly owing to the increase image resolution, which reflects the value of stander deviation for the blue band
... Show MoreThe aim of this research is to construct a three-dimensional maritime transport model to transport nonhomogeneous goods (k) and different transport modes (v) from their sources (i) to their destinations (j), while limiting the optimum quantities v ijk x to be transported at the lowest possible cost v ijk c and time v ijk t using the heuristic algorithm, Transport problems have been widely studied in computer science and process research and are one of the main problems of transport problems that are usually used to reduce the cost or times of transport of goods with a number of sources and a number of destinations and by means of transport to meet the conditions of supply and demand. Transport models are a key tool in logistics an
... Show MoreThe purpose of this paper is to model and forecast the white oil during the period (2012-2019) using volatility GARCH-class. After showing that squared returns of white oil have a significant long memory in the volatility, the return series based on fractional GARCH models are estimated and forecasted for the mean and volatility by quasi maximum likelihood QML as a traditional method. While the competition includes machine learning approaches using Support Vector Regression (SVR). Results showed that the best appropriate model among many other models to forecast the volatility, depending on the lowest value of Akaike information criterion and Schwartz information criterion, also the parameters must be significant. In addition, the residuals
... Show MoreSince the emergence of the science of international relations as an independent academic scientific field, various theories and trends have appeared and have tried to understand and explain the international reality and give a clear picture of what is happening within the international system of interactions and influences and the search for tools for stability and peace in international relations. Among these theories is the feminist theory, which is a new intellectual trend on the level of international relations theories, which tried to give an explanation of what is happening in world politics and in international relations in particular. The main issue that feminist theory is concerned with is the lack of women’s subordination
... Show MoreBackground: Recurrent aphthous stomatitis (RAS) is one of the most common oral mucosal disorders with a prevalence of 50-66%. The prevalence of hematinic deficiencies including ferritin and vitamin B12 deficiencies and their role in the prophylaxis and development of RAS is not well known. Many studies have demonstrated a high prevalence of hematinic deficiencies in patients with RAS. This study aimed to compare the serum level of ferritin and vitamin B12 in patients with recurrent aphthous ulcers and healthy controls. Subjects, Materials and Methods: The data were collected from patients who needed blood analysis to exclude anemia from November 2020 to May 2021. The study was approved by the institutional ethics committee. After recordi
... Show MoreIn addition to its basic communicative function, language can be used to imply information that is not actually stated, i.e. addressers do not always state exactly (or directly) what they mean. Such instances fall within the domain of pragmatics in that they have to do with how addressers use language to communicate in a particular situation by implication rather than by direct statement. The researcher attempts to demonstrate that the beauty and the multiple layers of meaning in poetry can be better explored if the addressee looks at the lines from a pragmatic perspective in search for implied meaning. There are many devices that can convey implied meaning in poetry, among which are 'rhetorical', 'figurative' or 'literary' devices. But
... Show MoreAbstract. In this research, the uranium concentration in (16) water samples collected from some agricultural areas surrounded with AlTuwitha nuclear site in Baghdad-Iraq was measured by using a CR-39 detector. The concentration of uranium in this study was from (0.6 ± 0.33mg/l) to (2.51 ± 0.49 mg/l), and the weighted average for the concentrations (1.262 ± 0.402 mg/l). The results showed it is a concentration of uranium level in water samples studied is higher than the allowed limit recommended by WHO and ICRP.