Background/: Buccal tubes are orthodontic attachments used on the posterior teeth instead of bands, so it is important to focus on the effect of their properties on orthodontic treatment. The aims of the present in vitro study are to evaluate and compare the buccal tube front and back openings dimensions and the torsional play angle of six different brands. Materials and Methods: The samples consisted of Single bondable, non-convertible first molar buccal tubes from six brands supplied from six companies (Dentaurum, Forestadent, Ormco, 3M, American Orthodontic, A-Star). Regarding tube opening dimension, ten buccal tubes of each brand were examined by an optical microscope. Each tube was fixed during examination using synthetic mud and oriented for observation of the front and back slot openings. A picture was taken for both tube openings and the result appeared on the computer's screen where width and height measurements were made. While regarding torsional play angle, ten buccal tubes of each brand were used. Each tube was fixed on a metal block attached to a surveyor base. Then an L-shaped wire was inserted inside the front opening of the tube. Two photographs were taken, one with the wire in free fall position and the other with the wire elevated by a 10g weight with the same angle of shooting as the first photograph. Later, the two images were superimposed in Adobe Photoshop program, and an electronic MB-ruler Software was used to calculate the angle which represents the torsional play within each tube. The data were then statistically analyzed using ANOVA and LSD tests. Results: There are marked differences between measured tube dimensions and the manufacturer stated dimensions with the front tube openings being generally larger than the back opening dimensions. Furthermore, the torsional play angle was highest in A-Star and smallest in Ormco's tubes. This angle was significantly correlated to the height of the tube front opening. Conclusion: It can be concluded that tube dimension varies among different companies and effect greatly torsional play angle.
In this research the behavior of reinforced concrete columns with large side openings under impact loads was studied. The overall cross sectional dimensions of the column specimens used in this research were (500*1400) mm with total height of (14000) mm. The dimensions of side openings were (600*2000) mm. The column was reinforced with (20) mm diameter in longitudinal direction, while (12) mm ties were used in the transverse direction. The effect of eccentric impact loads on the horizontal and vertical displacement for this column was studied. &
... Show MoreA long-span Prestressed Concrete Hunched Beam with Multi-Opening has been developed as an alternative to steel structural elements. The commercial finite element package ABAQUS/CAE version 2019 has been utilized. This article has presented the results of three-dimensional numerical simulations investigating the flexural behaviour of existing experimental work of supported Prestressed Concrete Hunched Beams with multiple openings of varying shapes under static monotonic loads. Insertion openings in such a beam lead to concentrate stresses at the corners of these openings; as a result, extensive cracking would appear. Correlation between numerical models and empirical work has also been discussed regarding load displacemen
... Show MoreTo find out a simple and efficient equation to estimate maize ear grain weight on farm (in situ), twenty three maize crosses along with two synthetics were grown in the field. On the experimental farm of the Dept. of Field Crop Sci., College of Agric., Univ. of Baghdad, seeds of twenty five maize genotypes were grown in the fall season of 2013 with three replicates. At dough stage of the kernels, five naked ears of each experimental units were measured for length and maximum diameter. This will sum up 125 ears of the trial. The volumes of ears were calculated as cylinder (length× r2× 3.1416). Grain weight of all ears were determined after harvesting and drying to 15% grain moisture. A constant was calculated by dividing ear grain weight b
... Show MoreUnderstanding of in-situ stress profiles and orientations plays a vital role in designing a successful hydraulic fracturing treatment. This paper is an attempet to examine the effect of lithology and in situ stress on geometery of hydraulic fractures. A hydraulic fracturing design simulator software called FracproPT with various capabilities for designing most of hydraulic fracture was used for simulate and optimize the hydraulic fracturing. For studying purpose, three different cases of stress gradient contrast between different formations are considered in this study (0.4, 0.5 and 0.75 psi/ft). The results obtained from the simulator showed that lithologies surrounding the pay zone have an effect on the fracture
... Show MoreAbstract Background: The hip joint and lumbar spine are both anatomically and functionally closely related as had shown by many authors. So the abnormality in one area can affect the other e.g. hip joint osteoarthritis can cause lumbar sagittal malalignment and backache. Objectives: is to see if there is significant improvement in backache after total hip replacement? And which degree of backache improvement is associated with significant changes in lumbar lordosis? Methods and patients: a prospective open trial study was performed on 30 patients who had severe hip osteoarthritis and chronic low back pain. Total hip replacement was performed to all patients. Backache and lumbar lordosis were measured by visual analogue scale and Cobb’s a
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