Background: Nickel-titanium (NiTi) archwires have become increasingly popular because of their ability to release constant light forces, which are especially useful during initial alignment and leveling phase. The aim of the present study was to investigate and compare the load–deflection characteristics of four commercially available NiTi archwires. Materials and methods: 200 NiTi 0.014, 0.016, 0.018, 0.016x0.022 and 0.019x0.025-inch nickel–titanium archwires from four different manufacturers (3M, Ortho Technology, Jiscop and Astar) were tested. The load-deflection properties of these archwires were evaluated by a full arch bending test in both palatal and gingival directionsat 37°C temperature using a universal material testing machine. Forces generated at maximumloading of 2mm and at unloading of 1.5mm were measured. Results: All the tested NiTi wires showed an increase in loading and unloading force with increased wire dimension.Generally, 3M gave the most flexible round wires and relatively stiff rectangular wires; with linear load deflection curves. Ortho Technology wires were flexible. Jiscop gave the stiffest round wires and the most flexible rectangular wires. Astar wires were stiff which gave the highest force levels during unloading. Conclusion: Force levels vary greatly from brand to brand and soNiTi wire brands must be selected with consideration to their load-deflection characteristics and mechanical properties.
Background: One common undesirable side effect of orthodontic treatment with fixed appliances is the development of incipient caries lesions around brackets, particularly in patients with poor oral hygiene. Different methods have been used to prevent demineralization; the recent effort to improve the resistance against the demineralization is by the application of lasers. Materials and method: Thirty human premolars extracted for orthodontic purposes were used to test the effect of two energy level of ER-YAG laser on enamel resistance to demineralization. The brackets were bonded on the teeth and all the labial surface excluding 2 mm area gingival to the brackets were painted with acid resistance varnish. Three groups were generated. The fi
... Show MoreABSTRACT Background: This study measured the effects of three parameters pH value, length of immersion and type of archwire on metal ions released from orthodontic appliances. Materials and Methods: Ninety maxillary halves simulated fixed orthodontic appliances that were immersed in artificial saliva of different pH values (6.75, 5 and 3.5) during 28 day period. Three types of archwires were used: stainless steel, nickel titanium and thermal activated nickel titanium. The quantity of nickel and chromium ions was determined with the use of atomic force spectrophotometer while iron ions by spectrophotometer. Each orthodontic set was weighted two times, before the ligation and immersion in the artificial saliva and after 28 days at the end of
... Show MoreBackground: It may be an important prospective clinical use of manufacturing of porous implant for clinical situations, such as cases of limitation in bone height, low bone density .The small segment of porous implant an effective osseointegration allows increasing in contact area provided for small segmented porous provided by its surface configuration. This study was done to Fabricate porous titanium implants by powder technology, as well as the observation of removal torque values of porous titanium implants compared to smooth titanium implants. Materials and methods: Twenty porous titanium implants (3.2mm in diameter and 8mm in length) were manufactured by powder technology using commercially pure titanium powder of ≤75um part
... Show MoreIn-situ gelation is a process of gel formation at the site of application, in which a drug product formulation that exists as a liquid has been transformed into a gel upon contact with body fluids. As a drug delivery agent, the in-situ gel has an advantage of providing sustained release of the drug agent. In-situ gelling liquid suppositories using poloxamer 188 (26-30% W/W) as a suppository base with 10% W/W naproxen were prepared, the gelation temperature of these preparations were measured and they were all above the physiological temperature. Additives such as polyvinylpyrrolidin "PVP" ,hydroxylpropylmethylcellulose "HPMC", sodium alginate and sodium chloride were used in concentration ranging from (0.25-1
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Meloxicam (MLX) is non-steroidal anti -inflammatory, poorly water soluble, highly permeable drug and the rate of its oral absorption is often controlled by the dissolution rate in the gastrointestinal tract. Solid dispersion (SD) is an effective technique for enhancing the solubility and dissolution rate of such drug.
The present study aims to enhance the solubility and the dissolution rate of MLX by SD technique by solvent evaporation method using sodium alginate (SA), hyaluronic acid (HA), collagen and xyloglucan (XG) as gastro-protective hydrophilic natural polymers.
Twelve formulas were prepared in different drug: polymer ratios and evaluated for their, percentage yield, drug content, water so
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The aim of the present study is to formulate floating effervescent microsponge tablet of the narrow absorption window drug, Baclofen (BFN) for controlling drug release and thereby decrease the side effect of the drug. The microsponges of BFN were prepared by non-aqueous emulsion solvent diffusion method (oil in oil emulsion method). The effects of drug: polymer ratio, stirring time and type of Eudragit polymer on the physical characteristics of microsponges were investigated and characterized for production yield, loading efficiency, particle size, surface morphology, and in vitro drug release from microsponges. The selected microsponge formula was incorporated into the floating effervescent gastro-retentive tablet. The prepared fl
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The preferred route of drug administration is the oral route, but drugs with narrow absorption window in the gastrointestinal tract are still challenging. The ability to extend and monitor the gastric emptying time is a valuable tool for processes remaining in the stomach longer than other traditional dosage forms.
The purpose of this study was to formulate and evaluate gastroretentive superporous hydrogel (SPH) of carvedilol with view to improve its solubility and increase gastric residence time in order to get sustained release formulas via utilization of various kinds and concentrations of hydrophilic polymers then after, incorporate the best prepared formula into capsules.
Sixteenth formulae of SPH h
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Background: This study report the corrosion behavior of commercially pure titanium and Ti-6Al-4V alloy samples without coating and with hydroxyapatite, partial stabilized zirconia and mixture of partial stabilized zirconia and hydroxyapatite coating and comparison between them through electrochemical polarization tests in 37 0 C Hank's solution. Materials and methods: Electrophoretic deposition technique (EPD) was used to achieve the coating from each one of three types of the coating materials (HAP, PSZ and mixture of 50% HAP and 50%PSZ) on Cp Ti and Ti-6Al-4V alloy samples. The electrochemical corrosion test was performed when samples were exposed to Hank's solution prepared in the laboratory and the polarization potential, corrosion rate
... Show MoreObjective: Carbamazepine is typically used for the treatment of seizure disorders and neuropathic pain. One of the major problems with this drug is its low solubility in water; therefore the objective of this study was to enhance the solubility of carbamazepine by complexation with cyclodextrin to be formulated as effervescent and dispersible granules.Methods: Solvent evaporation method was used to prepare, binary (Carbamazepine/β-cyclodextrin) complex and ternary (Carbamazepine/β-cyclodextrin/hydroxypropyl methyl cellulose (HPMC E5). The more soluble complex will be further formulated as unit dose effervescent and dispersible granules. The complexes were evaluated for their solubility, drug content, percentage practical yield and
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