Effect of different fluoride pretreatments on adhesion to enamel and dentin using a universal adhesive

Abstract

Objectives To evaluate and compare the bond strength of bulk fill composite when bonded to enamel or dentin pretreated with different concentrations of fluoride (F) compounds using a universal adhesive. Methods A total of 120 teeth were used, including 40 enamel specimens and 80 dentin specimens. Enamel specimens were ground flat, while dentin specimens were prepared by cutting until mid-coronal dentin. The teeth were divided into four groups (n = 30) to test the F-based agents: 1.23% acidulated phosphate fluoride (APF), 1.1% neutral sodium fluoride (NSF), 0.4% stannous fluoride (SF), and a control group without F pretreatment. Each agent was applied for 30 s and rinsed before bonding. Enamel specimens underwent phosphoric acid etching (ER), while dentin specimens were bonded using either ER or self-etch (SE) protocols. Microtensile bond strength testing (μTBS) was performed after 24 h or 10,000 thermal cycles, and failure patterns were assessed. Results The study variables did not significantly affect μTBS values of enamel specimens. However, all study variables had a significant effect on μTBS values of dentin specimens. The ER protocol, after both control and SF pretreatment, exhibited the highest μTBS values. Conclusions Pretreatment of enamel with different concentrations of F prior to bonding appears to be safe in terms of bond durability. However, pretreatment with F concentrations higher than 1000 ppm adversely affected bonding to dentin. Clinical significance Pretreating tooth structure with F-based agents at concentrations below 1000 ppm prior to bonding shows promise as a viable option without compromising bond durability.