Microtensile bond strength to phosphoric acid-etched dentin treated with NaF, KF and CaF 2

Abstract Purpose Fluoride compounds have been reported to play a protective role in the host-derived enzymatic degradation of demineralized dentin matrices. The objective of this study was to evaluate the effect of fluoride pretreatment on the immediate and long-term microtensile bond strength (µTBS) of resin-dentin interfaces. Materials and methods Mid-coronal dentin surfaces of ninety-nine teeth were etched with 32%wt phosphoric acid and randomly assigned to pretreatment with NaF, KF or CaF 2 solutions (6, 24 and 179 mM F content) for 30 s before the application of bonding agent (Scothbond Multi-Purpose, 3 M ESPE). No fluoride pretreatment and a commercially available bonding agent with KF (Excite F, Ivoclar Vivadent) were used as controls. After composite built-up, the specimens were sectioned into µTBS test beams, stored in artificial saliva at 37 °C for 24 h, 6 or 12 months and tested. Fracture types were evaluated under scanning electron microscope. The data were analyzed with ANOVA and Scheffe post-hoc tests (α = 0.05). Pearson Chi-Square test was used to compare the distribution of failure types. Results Fluoride compound, fluoride concentration and storage time showed significant effect on µTBS (p 0.05), except CaF 2 179 mM (p Conclusions NaF and KF treatment after acid-etching step of adhesive bonding procedures do not adversely influence the initial or long-term bond strength to dentin, and can improve the maintenance of bond strength durability.