Background: Elastomeric chains are one of the most commonly used force delivery systems. They have the ability to exert a continuous force, convenience of use, compatibility to oral environment and cost effectiveness but one of the inherited disadvantages is force degradation. Materials and methods: This in vitro study was designed to evaluate the effect of alcohol presence in mouthwashes on force decay of different configurations of clear elastomeric chains from (Ortho Technology company) which are: closed , short and long under the effect of time at (Initial, 1, 2, 3 and 4 weeks) intervals with exposure to different chemical solutions. A total (540) modules of elastomeric chains of three different types (long, short and closed) transparent in color, with an initial length (19mm) and about 50% extension (29mm) were used for the study. These elastomeric chains divided in to four groups and exposed to different chemical solutions (Listerine Original alcoholic mouthwash, Listerine Zero alcohol mouth wash, Ethanol 26.9%, distilled water) twice daily for 60 seconds according to manufacturer instructions to measure the amount of force degradation in different time intervals. These elastomeric chains were incubated in covered glass containers at 37C˚ for the entire testing period. Results: Statistical analysis showed that there was a highly significant difference in the mean percentage of force decay (P≤ 0.001). For all chemical solutions the highest percentage of force decay occurs in Listerine Original Alcoholic mouth wash. Also in all chemical solutions closed elastomeric chains has the least percentage of force decay. While closed configuration have the highest percentage of force decay. Conclusion: We can conclude that alcoholic mouth wash(Listerine Original) causes increase force degradation of all types of elastomeric chains while alcohol free mouth wash (Listerine Zero) causes less force degradation of all types of elastomeric chains. Also closed configuration elastomeric chains have the least percentage of force decay than other configurations.
ABSTRACT Background: One of the major problems of all ceramic restorations is their probable fracture against the occlusal forces. The objective of this in vitro study was to evaluate the effect of two gingival finishing lines (90°shoulder and deep chamfer) on the fracture resistance of full contour CAD/CAM and heat press all-ceramic crowns. Materials and Methods: Thirty two maxillary first premolars were prepared to receive full contour CAD/CAM (zolid) and heat press (Cergo Kiss) ceramic crowns using a special paralleling device (Parallel-A-Prep). The teeth were divided into four groups according to the type of finishing line prepared. Each crown was cemented to its corresponding tooth using self-etch, self-adhesive dual cure resin ceme
... Show MoreThe creation and characterisation of biodegradable blend films based on chitosan and polyvinyl alcohol for application in a range of packaging is described. The compatibility between the chitosan and PVA polymers was good. Composite films had a compact and homogeneous structure, according to the morphology analysis. The mechanical test result of PVA/CH at concentrations 5% showed, that The higher values of TS recorded in sample (p1, with 40 MPa) while the lower values appeared in sample (p9, with 22.09 MPa), the TS decreased gradually as the amount of PVA increased in blend film. While the blend film of pure Chitosan exhibits a poor mechanical strength which makes it a poor candidate for packaging but Blending CH with PVA together improved
... Show MoreThis study was conducted to test the effect of aqueous and alcoholic extracts for cyperus rotundus on the mitosis in tap roots of Allium cepa. the result of general an identical qualitative tests showed contains certain compounds that of crude aqueous and alcoholic extract, Used as five different concentrations of (10, 20.38, 56, 75) mg / ml for a period of four hours of treatment. After the chemical has been detected for some preliminary chemical compounds of the crude aqueous extract, while the alcoholic extract either phenol compound has been detected for phenols using several techniques included the use of thin layer chromatography TLC and measurement of disability factor RF and the degree of fusion and measurement of absorbance. The r
... Show MoreBackground: The success and maintenance of indirect dental restorations is closely related to the marginal accuracy, which is affected by many factors like preparation design, using of different fabrication techniques, and the time of taking final impression and pouring it. The purpose of this in vitro study was to evaluate the effect of different pouring time of conventional impression on the vertical marginal gap of full contour zirconia crowns in comparison with digital impression technique. Materials and Methods: Forty sound recently extracted human permanent maxillary first premolar teeth of comparable size and shape were collected. Standardized preparation of all teeth samples were carried out to receive full contour zirconia crown re
... Show MoreBackground: The success and maintenance of indirect dental restorations is closely related to the marginal accuracy, which is affected by many factors like preparation design, using of different fabrication techniques, and the time of taking final impression and pouring it. The purpose of this in vitro study was to evaluate the effect of different pouring time of conventional impression on the vertical marginal gap of full contour zirconia crowns in comparison with digital impression technique. Materials and Methods: Forty sound recently extracted human permanent maxillary first premolar teeth of comparable size and shape were collected. Standardized preparation of all teeth samples were carried out to receive full contour zirconia crown re
... Show MoreAbstract\
The value chain analysis is main tools to achieve effective and efficient cost management; it requires a depth and comprehensive understanding for all internal and external activities associated with creating value. Supply chain as apart of value chain, that means managing it in active and efficient can achieve great results when adopting a comprehensive and integrated performance for these two chains activities. The research aims to identify possible ways to integrate the performance of value and supply chains of the sample" Kufa-cement plant" and determine the effect of this integration in enhancing customer value. The research arrival that logical and integrated analysis of value and supply chains helps
... Show MoreThe aim of this research is to study the influence of additives on the properties of soap greases, such as lithium, calcium, sodium, lithium-calcium grease, by adding varies additives, such as graphite, molybdenum disulfide, carbon black, corrosion inhibitor, and extreme pressure.
These additives have been added to grease to obtain the best percentages that improve the properties of grease such as load carrying, wear resistance, corrosion resistance, drop point, and penetration.
The results showed the best weight percentages to all types of grease which give good properties are 1.5% extreme pressure additive, 3% graphite, 1% molybdenum disulfide, 2.5% carbon black.
The other hand, the best weight percentage for corrosion inhibit
Background: Biologically active substances, such as Cathepsin B (CAB) which is a lysosomalcystein protease may be involved in periodontal metabolism in the degradation of organic bone matrix containing collagen fibers in response to mechanical stress from orthodontic appliance. The aims of study were to determine and compare salivary levels of CAB, pH as well as clinical periodontal parameters (Plaque index PLI and gingival index GI) with different orthodontic force magnitudes at different time intervals. Materials and methods: A twenty-four patients (both gender) with age range (17-23) years had Angle's Class II division 1 malocclusion with GI >0.5 enrolled in this study. The level of salivary CAB and pH, in addition to the clinical period
... Show More