A STUDY OF SHEAR BOND STRENGTH AND FAILURE PATTERNS IN LIGHT-AND SELF-CURED ORTHODONTIC RESIN

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Journal of the Korean Academy of Pediatric Dentistry 1996;23(2):549-558.
Published online May 31, 1996.

A STUDY OF SHEAR BOND STRENGTH AND FAILURE PATTERNS IN LIGHT-AND SELF-CURED ORTHODONTIC RESIN

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²

교정용 광중합형 및 화학중합형 레진접착제의 전단결합강도와 파절양상에 대한 연구

이민하¹, 양규호¹, 박영준²

¹전남대학교 치과대학 소아치과학교실
²전남대학교 치과대학 치과재료학교실

Abstract

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 in 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-Lok 2), 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. The results were as follows : 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.