| Abstract:
Background and aim: The aim of this study was to evaluate the effect of etching solution containing various ratio of APF on orthodontic brackets bonding & enamel surface. Direct bracket bonding has many advantages & also disadvantages. The main problem is enamel loss & demineralization under & around brackets. Although phosphoric acide used for etching enamel before bracket bonding, it can be buffered by APF to decrease the adverse affect of it on enamel & this mixture may lead to adverse affect on shear bond strenght too. Unfortunately enamel damage may occure when debonding. It seams that the main benefet of using this kind of exprmental etching solution is to decrease the enamel loss during bonding & debonding procedures.
MATERIALS & METHODES: 40 extracted human premolars from 10, 4 premolars extraction case paitiont were stored in 0/1% thymol solution. They were examined macroscophaly to insure that the buccal surface was both intact & caries-free & divided randomly in to 4 groups of 10 teeth. After cleaning the buccal surface with fluoride-free pumice each of them were etched with phosphoric acide solution containing 0, 25%, 50%, 75% of APF. Then brackets bonded to the teeth in the same situation as the company recommended. The dete were analysed with ANOVA Test & Tukey Post Hoc Test. After debonding test, the debonded enamel surface were examined using steriomicroscope with 10× magnification & the amount of adhesive remaining on enamel surface for each tooth was scored as the adhesive remained index & analyzed by Chi-square Test.
RESULTS: The result of this research indicates that, shear bond strenght between enamel & adhesive decreased when APF added to etch solution. Also ARI decreased by adding APF to etch solution & the sit of bond failure in exprmental groups was between enamel & resin.
CONCLUSION: Mixture of 25% APF+75% H3PO4 37% can be used in clinic as an etchant to minimize enamel loss during etching as well as debonding procedure with out compromising the requaried bracket bond strenght.
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