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KMID : 0353320110350010022
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Oral Biology Research
2011 Volume.35 No. 1 p.22 ~ p.29
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Comparison of physical characteristics of elastomeric chains
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Lim Hyun-Cheol
Lim Sung-Hoon
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Abstract
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The purpose of this study was to investigate the effect of extension speed on load-deflection characteristics of elastomeric chains, and stress relaxation of elastomeric chains during uninterrupted extension of 4 weeks. Gray and transparent elastomeric chains from Ormco, 3M Unitek, RMO were tested. For load-deflection test, elastomeric chains were extended 10 mm (102% to 105% extension) with two extension speed of 10 mm/sec and 0.1 mm/sec. For stress relaxation test, the elastomeric chains were extended 10 mm and maintained on the force gauge for 4 weeks. When the extension speed was lowered to 0.1 mm/sec, forces during both extension and unloading decreased significantly, and the permanent deformation increased significantly. The initial force of elastomeric chains decreased 23% to 48% during initial 12 hours of constant extension, and then decreased 8% to 11% more during the rest of 4 week period. After 4 week of constant extension, the remaining force was 67% (transparent), 69% (gray) in RMO chains, 60% in Ormco chains, 41% (gray) to 50% (transparent) in Unitek chains. Stress relaxation of elastomeric chain seems to start at the start of extension procedure thus lowering the force level of elastomeric chain when extended more slowly, and it is recommended to determine initial force level of elastomeric chain considering the stress relaxation pattern revealed in this study.
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KEYWORD
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Elastomeric chain, Load-deflection, Permanent deformation, Stress relaxation
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