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KMID : 0376319950070010393
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Dental Journal of CNU
1995 Volume.7 No. 1 p.393 ~ p.402
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A Study of Shear Bond Strength and Failure Patterns in Light-and Self-Cured Orthodontic Resin
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Abstract
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Light-cured orthodontic composite resin has been widely advertised recently for use in bonding brackets. However, the curability of light-cured resin when light waves are diffused through metal brackets is questionable.
The purposes of this study were to evaluate shear bond strength and failure patterns of visible light-cured resin (Lightbond) and chemically cured-resin (Mono-Lok2), and to determine the relative value of light-cured resin as an alternative to
conventional chemically-cured resin. Each of the two resins was tested on twenty extracted human first premolars. Standard edgewise metal brackets were bonded to the teeth in accordance with the manufacturers' recommendation. After bonding, the
teeth
were stored for 24 hours at 37℃, 100% humidity. The shear bond strength was tested with a universal testing machine (Instron 4302), at 0.5mm/min crosshead speed. After debonding, brackets and enamel surfaces were examined with a scanning
electron
microscope and a stereoscopic microscope.
@ES The results were as follows:
@EN 1. Metal brackets bonded with Lightbond showed statistically higher shear bond strength than metal brackets bonded with Mono-Lok2.
2. The predominant failure site in Lightbond was the enamel-resin interface, and in Mono-Lok 2 it was the resin itself.
3. Enamel cracks were not found in any specimen.
The above results suggest that direct bonding of metal brackets to enamel with light-cured resin bonding agent can be used effectively in clinics.℃℃
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