effects of two soft drinks on shear bond strength and adhesive remnant index of orthodontic metal brackets.

bond failure of brackets during orthodontic treatment is a common problem; which results in treatment interference, increased treatment time and prolonged clinical time for rebonding of failed brackets. the purpose of this study was to evaluate the effects of coca-cola and a non-alcoholic beer on the shear bond strength and adhesive remnant index (ari) of orthodontic metal brackets in vitro.eighty intact human premolars were divided into two experimental groups of coca-cola and non-alcoholic beer (istak), and a control group of artificial saliva. over a period of thirty days, the test groups were immersed in the respective soft drinks for 5 minutes, twice a day. for the remainder of the time, they were kept in artificial saliva at 37°c. the control group was stored in artificial saliva during the experiment. all samples were subjected to shearing forces using universal testing machine. ari was determined with a stereomicroscope at ×12 magnification. the data of shear bond strength were statistically analyzed by one-way anova and tukey's post-hoc test and the data of ari scores were analyzed by kruskal-wallis test.no significant difference was observed in aris of the three groups (p≤ 0.552). the shear bond strength of coke group was significantly lower than that of the two other groups (p≤ 0.035); but there was no significant difference between the shear bond strength of istak and the control group (p≤ 0.999).coca-cola decreased the shear bond strength of orthodontic brackets.