In vitro evaluation of the effect of different chemical solvent agents on shear bond strenght of ceramic orthodontic brackets

The aim of this study was to evaluate the effects of different chemical organic solvents on shear bond strengths (SBS) of ceramic brackets and to find a new approach for ceramic bracket debonding. 132 human premolar teeth extracted for orthodontic purposes were randomly divided in 11 groups each consisting of 12 samples. 10 groups consisting of 5 different organic solvents (acetone, ethanol, dimethyl sulfoxide, peppermint oil, hot water) with 2 different durations (5 and 15 minutes) and a control group were subjected to test. SBS were applied using universal test machine following thermocycling procedure. The amount of residual adhesives were determined through ARI scoring. SEM images were examined to determine the effects of solvents on enamel surface. In all test groups, the highest SBS values were found in ethanol 5 and 15 minutes groups which were also found statistically significantly higher than the control group. SEM examination showed micro-cracks in all groups while in both ethanol groups, the depth of cracks were found to be remarkably higher causing the highest damage on enamel surface. Increased SBS values were also found in 5 and 15 minutes groups of hot water and dimethyl sulfoxide while both peppermint oil groups had similar SBS values as control group. SBS values of both acetone 5 and 15 minutes groups were found statistically significantly lower than the control and other groups. Acetone application for 5 or 15 minutes before debonding of ceramic brackets could be an alternative clinical approach to prevent enamel damage and facilitate debonding. Key words: Ceramic Bracket, Shear Bond Strength, Organic Chemical Solvent, Acetone, Ethanol