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KMID : 0376320000120010377
Dental Journal of CNU
2000 Volume.12 No. 1 p.377 ~ p.383
Change of fracture mode of orthodontic resin bracket wings under water immersion and thermal change


Abstract
The purpose of this study was to evaluate the effect of oral environment on the strength of resin bracket wings by comparing fracture mode according to water immersion and thermal change.
Seventy-five resin brackets(Spirit MB, Ormco, California) were divided into three groups and treated for six months as follows: (1) untreated, (2) water immersion in distilled water at 37t, (3) water immersion in distilled water at 37¢¥C with total 2,100 times of thermocycling taken 350 times each month. Fracture mode of the wing was tested on universal testing machine. In addition to resin brackets, 25 metal brackets were used as oontrols. Through the statistical analyses, following results were obtained.
1. Resin bracket wings showed significantly lower fracture strength than metal brackets(p<0.001).
2. Water immersion and water immersion with thermocycling groups showed significantly lower fracture strength than open air condition group(p<0.001).
3. Waf^r immersion with thermocycling group showed significantly lower fracture strength than water immersion group(p<0.001).
The above results suggest that the mechanical property of resin bracket wing may be influenced by oral environment and further research is needed to improve the strength of the wing in the resin bracket.
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