Effect of nano-hydroxyapatite incorporation on the immediate and long-term bond stability of a one-step self-etch adhesive

Objective: This study evaluated the effect of incorporating nano-hydroxyapatite (nHAp) at various concentrations on the immediate and long-term bond strength of a one-step self-etch adhesive to dentin.Methods: A total of ۱۰۰ sound maxillary central incisors were collected. The dentin was exposed on the labial surfaces, and the teeth were randomly assigned into two groups (n=۵۰) based on the evaluation time points: ۲۴ hours and ۶ months. Each group was further divided into five subgroups (n=۱۰) based on the concentration of nHAp (۰, ۱, ۲, ۳, and ۴ wt%) incorporated into Adper Single Bond Universal adhesive. Composite resin buildups were formed on dentin using cylindrical molds, and light-cured. Shear bond strength (SBS) was measured by a universal testing machine, and fracture modes were assessed under a stereomicroscope. Statistical analysis was performed using a two-way ANOVA (P<۰.۰۵).Results: At ۲۴ hours, the highest bond strength was observed in ۲% nHAp (۴۱.۶۸ ± ۱۵.۲۴ MPa), followed by ۱% nHAp (۳۶.۷۵ ± ۱۴.۲۴ MPa), both significantly greater than the control group (۰% nHAp: ۱۷.۰۳ ± ۴.۵۷ MPa; P < ۰.۰۵). After ۶ months, ۲% nHAp again demonstrated the highest bond strength (۴۳.۲۸ ± ۶.۸۷ MPa), followed by ۱% nHAp (۳۷.۰۰ ± ۶.۹۰ MPa), both significantly higher than the control (۱۵.۲۸ ± ۴.۶۳) and ۴% nHAp groups (۱۴.۵۸ ± ۲.۳۳ MPa; P<۰.۰۵).Conclusions: The incorporation of nano-hydroxyapatite at concentrations up to ۲ wt% into a one-step self-etch adhesive significantly enhanced both immediate and long-term bond strength to dentin.

کلیدواژه ها:

Adper single bond ، Bond Strength ، Composite resins ، dental cement ، dentin bonding agents ، Nano-hydroxyapatite