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The influence of relative humidity on the effect of dentin bonding systems
1Department of Dental Materials, School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Denmark. ea@odont.ku.dk
Purpose:
The aim of the study was to measure the influence of relative humidity of the ambient air on bond strength to enamel and dentin of six different bonding systems. In this manner, the role of the primer solvent was assessed.
Materials And Methods:
The bonding systems selected were Prime & Bond 2.1, One Step, Scotchbond MP, Syntac Single Component, Optibond Solo, and Perma Quick. The primers of these systems are based on either acetone, water or ethanol. Plane enamel and dentin surfaces were placed at relative humidities of 18%, 45%, 80% or 99% RH and then treated in accordance with the recommendations of the respective manufacturers. A resin composite was then bonded to the treated surfaces. After storage in water at 37 degrees C for 1 day, the bonded specimens were broken in shear.
Results:
The bonds to enamel were either unaffected or in one case moderately increased by increasing ambient humidity. The bonds to dentin were either unaffected or in four cases strongly reduced by increasing humidity.
Conclusions:
The response of the bonding systems to differences in ambient humidity were not related to the solvent of the primer in a simple way. To exclude the damaging effect of high humidity on dentin bonding, the use of rubber-dam is recommended.