Shear bond strength of brackets to demineralize enamel after different pretreatment methods

To compare the influence of demineralized and variously pretreated demineralized enamel on the shear bond strength of orthodontic brackets.

Sixty bovine enamel specimens were allocated to five groups (n  =  12). Specimens of group 1 were not demineralized and were not pretreated, but served as controls. The other specimens were demineralized to form artificial carious lesions. Samples from group 2 were only demineralized and were kept untreated in artificial saliva. The other samples were pretreated with highly concentrated fluoride preparations (group 3: Elmex Gelee, 1.23% F; group 4: Clinpro White Varnish, 2.23% F) or with an infiltrating resin (group 5: Icon). After respective pretreatments, brackets were adhesively fixed on all specimens with an adhesive system after etching with 35% phosphoric acid and application of a primer and bracket resin cement (Transbond XT). Bracket shear bond strength was evaluated with a universal testing machine. Statistical analysis was performed by one-way analysis of variance followed by a post-hoc Scheffé test.

Shear bond strength in control group 1 was statistically significantly greater compared with that in all other groups. Application of the infiltrating resin Icon (group 5) as pretreatment resulted in statistically significantly greater bond strength as compared with pretreatments with fluoride compounds (groups 3 and 4) and treatment provided without pretreatment (group 2). Groups 2, 3, and 4 did not significantly differ from each other.

Pretreatment with the infiltrating resin is a beneficial approach to increasing the shear bond strength of brackets to demineralized enamel.