The Experts below are selected from a list of 78 Experts worldwide ranked by ideXlab platform
Martyn Sherriff - One of the best experts on this subject based on the ideXlab platform.
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An investigation into UV light exposure as an experimental model for artificial aging on tensile strength and Force Delivery of elastomeric chain
European Journal of Orthodontics, 2014Co-Authors: Siti Waznah Wahab, Dirk Bister, Martyn SherriffAbstract:This study investigated the effect of ultraviolet type A light (UVA) exposure on the tensile properties of elastomeric chain. UVA light exposure was used as model for artificial aging, simulating prolonged storage of elastomeric chain. Tensile strength (n = 60) was measured after exposing Ormco, Forestadent and 3M chains to UVA light for 0, 2, 3, and 4 weeks. Force decay was measured (n = 60) using chain exposed for 5, 10, and 14 days. The chains were subsequently stretched at a constant distance and the resulting Forces measured at 0, 1, 24 hours and 7, 14, 21, and 28 days. This test simulated a clinical scenario of pre-stretching and subsequent shortening of elastomeric chain. Tensile strength had statistically significant difference and was directly related to the duration of ultraviolet (UV) light exposure. Forestadent chain, which had the second highest value for the 'as received' product, showed the most consistent values over time with the lowest degradation. Ormco showed the lowest values for 'as received' as well as after UV exposure; 3M chain had the highest loss of tensile strength. Force decay was also significantly different. UV light exposure of 10 days or more appears to mark a 'watershed' between products: 3M had most survivors, Forestadent chain had some survivors, depending on the time the chain was stretched for. None of the Ormco product survived UV light exposure for more than 5 days. UVA light exposure may be used as a model for artificial aging as it reduces Force Delivery and tensile strength of exposed chains.
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an investigation into the placement of Force Delivery systems and the initial Forces applied by clinicians during space closure
Journal of Orthodontics, 1997Co-Authors: C Nattrass, Anthony J Ireland, Martyn SherriffAbstract:AbstractThis in vitro investigation was designed to establish not only how clinicians apply Forces for space closure when using the straight wire appliance and sliding mechanics, but also to quantify the initial Force levels produced. A single typodont, with residual extraction space in each quadrant, was set up to simulate space closure using sliding mechanics. On two occasions, at least 2 months apart, 18 clinicians were asked to apply three Force Delivery systems to the typodont, in the manner in which they would apply it in a clinical situation. The three types of Force Delivery system investigated were elastomeric chain, an elastomeric module on a steel ligature, and a nickel-titanium closed coil spring. A choice of spaced or unspaced elastomeric chain produced by a single manufacturer was provided. The amount of stretch which was placed on each type of system was measured and, using an Instron Universal Testing Machine, the initial Force which would be generated by each Force Delivery system was est...
S P Jones - One of the best experts on this subject based on the ideXlab platform.
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a clinical investigation of Force Delivery systems for orthodontic space closure
Journal of Orthodontics, 2003Co-Authors: Claire Nightingale, S P JonesAbstract:AbstractObjective: To investigate the Force retention, and rates of space closure achieved by elastomeric chain and nickel titanium coil springs.Design: Randomized clinical trial.Setting: Eastman Dental Hospital, London and Queen Mary’s University Hospital, Roehampton, 1998–2000.Subjects, materials and methods: Twenty-two orthodontic patients, wearing the pre-adjusted edgewise appliance undergoing space closure in opposing quadrants, using sliding mechanics on 0.019 × 0.025-inch posted stainless steel archwires. Medium-spaced elastomeric chain [Durachain, OrthoCare (UK) Ltd., Bradford, UK] and 9-mm nickel titanium coil springs [OrthoCare (UK) Ltd.] were placed in opposing quadrants for 15 patients. Elastomeric chain only was used in a further seven patients. The initial Forces on placement and residual Forces at the subsequent visit were measured with a dial push–pull gauge [Orthocare (UK) Ltd]. Study models of eight patients were taken before and after space closure, from which measurements were made to ...
Norehan Mokhtar - One of the best experts on this subject based on the ideXlab platform.
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Force Delivery of niti orthodontic arch wire at different magnitude of deflections and temperatures a finite element study
Journal of The Mechanical Behavior of Biomedical Materials, 2018Co-Authors: M F Razali, Abdus Samad Mahmud, Norehan MokhtarAbstract:NiTi arch wires are used widely in orthodontic treatment due to its superelastic and biocompatibility properties. In brackets configuration, the Force released from the arch wire is influenced by the sliding resistances developed on the arch wire-bracket contact. This study investigated the evolution of the Forces released by a rectangular NiTi arch wire towards possible intraoral temperature and deflection changes. A three dimensional finite element model was developed to measure the Force-deflection behavior of superelastic arch wire. Finite element analysis was used to distinguish the martensite fraction and phase state of arch wire microstructure in relation to the magnitude of wire deflection. The predicted tensile and bending results from the numerical model showed a good agreement with the experimental results. As contact developed between the wire and bracket, binding influenced the Force-deflection curve by changing the martensitic transformation plateau into a slope. The arch wire recovered from greater magnitude of deflection released lower Force than one recovered from smaller deflection. In contrast, it was observed that the plateau slope increased from 0.66N/mm to 1.1N/mm when the temperature was increased from 26°C to 46°C.
Claire Nightingale - One of the best experts on this subject based on the ideXlab platform.
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a clinical investigation of Force Delivery systems for orthodontic space closure
Journal of Orthodontics, 2003Co-Authors: Claire Nightingale, S P JonesAbstract:AbstractObjective: To investigate the Force retention, and rates of space closure achieved by elastomeric chain and nickel titanium coil springs.Design: Randomized clinical trial.Setting: Eastman Dental Hospital, London and Queen Mary’s University Hospital, Roehampton, 1998–2000.Subjects, materials and methods: Twenty-two orthodontic patients, wearing the pre-adjusted edgewise appliance undergoing space closure in opposing quadrants, using sliding mechanics on 0.019 × 0.025-inch posted stainless steel archwires. Medium-spaced elastomeric chain [Durachain, OrthoCare (UK) Ltd., Bradford, UK] and 9-mm nickel titanium coil springs [OrthoCare (UK) Ltd.] were placed in opposing quadrants for 15 patients. Elastomeric chain only was used in a further seven patients. The initial Forces on placement and residual Forces at the subsequent visit were measured with a dial push–pull gauge [Orthocare (UK) Ltd]. Study models of eight patients were taken before and after space closure, from which measurements were made to ...
C Nattrass - One of the best experts on this subject based on the ideXlab platform.
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an investigation into the placement of Force Delivery systems and the initial Forces applied by clinicians during space closure
Journal of Orthodontics, 1997Co-Authors: C Nattrass, Anthony J Ireland, Martyn SherriffAbstract:AbstractThis in vitro investigation was designed to establish not only how clinicians apply Forces for space closure when using the straight wire appliance and sliding mechanics, but also to quantify the initial Force levels produced. A single typodont, with residual extraction space in each quadrant, was set up to simulate space closure using sliding mechanics. On two occasions, at least 2 months apart, 18 clinicians were asked to apply three Force Delivery systems to the typodont, in the manner in which they would apply it in a clinical situation. The three types of Force Delivery system investigated were elastomeric chain, an elastomeric module on a steel ligature, and a nickel-titanium closed coil spring. A choice of spaced or unspaced elastomeric chain produced by a single manufacturer was provided. The amount of stretch which was placed on each type of system was measured and, using an Instron Universal Testing Machine, the initial Force which would be generated by each Force Delivery system was est...