Orthodontic bracket bonding: enamel bond strength vs time.
BACKGROUND
Tests of bond strength between orthodontic brackets and enamel are generally conducted after at least 24 hours storage in water. However, debonding might occur soon after bracket placement during orthodontic treatment. We investigated the rate of bond strength development for orthodontic adhesives in bracket bonding.


METHODS
Four orthodontic adhesive systems were examined. Bovine incisors were mounted in self-curing acrylic resin, and the facial surfaces were wet-ground to expose flat enamel. Orthodontic brackets were bonded according to the manufacturers' instructions. Shear bond strengths were measured after storage in water for 5, 10, and 60 minutes, and 24 hours. Differences between bond strengths at 24 hours and the other test periods were statistically analyzed.


RESULTS
All materials tested had the highest bond strengths at 24 hours, and bond strength increased with storage time. The earliest time point at which there was no significant difference in bond strength compared with that at 24 hours was defined as the initial stable time. Differences in this value might have clinical implications for the assessment of orthodontic adhesives, which can incur high stresses immediately after placement.


CONCLUSIONS
The rate of development of enamel bond strength must be considered to ensure sufficient maturation of orthodontic adhesives before functional loading.
Yamamoto
Akira
A
Department of Operative Dentistry, School of Dentistry, Nihon University, Tokyo, Japan.
Yoshida
Takeshi
T
Tsubota
Keishi
K
Takamizawa
Toshiki
T
Kurokawa
Hiroyasu
H
Miyazaki
Masashi
M
D000818:Animals; D002417:Cattle; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure; D003799:Dental Stress Analysis; D008855:Microscopy, Electron, Scanning; D016910:Orthodontic Brackets; D019279:Resin Cements; D033081:Shear Strength; D013499:Surface Properties; D013997:Time Factors
D019279:Resin Cements