Titanium tetrafluoride incorporated into a two-step self-etching adhesive system: physico-mechanical characterization and bonding stability.

Abstract

To evaluate the influence of TiF₄ incorporated into the primer (P) or bond (B) of a self-etching adhesive system on long-term dentin bonding, and evaluate the physico-mechanical properties of TiF₄-containing adhesives. Dentin surfaces received the following treatments (n = 8): CL (Clearfil SE Bond); TiF₄CL (dentin pretreatment with TiF₄ aqueous solution + CL); TiF₄P (TiF₄ incorporated into the P); TiF₄B (TiF₄ incorporated into the B). Microtensile bond strength (µTBS) and failure mode evaluations were performed after 24h, 6 months and one year, respectively. Degree of conversion (DC) and flexural strength (FS) were evaluated to determine whether TiF₄ influenced adhesive properties. Particle size (PS), polydispersity index (PI) and zeta potential (ZP) of TiF₄-containing adhesives were measured using dynamic light scattering. Two-way ANOVA for repeated measures was applied to µTBS data, and one-way ANOVA and Tukey tests to DC and FS results. There was no difference in µTBS among the groups (p = 0.818) regardless of time; the µTBS in each group was not significantly affected over time (p = 0.061). TiF₄P and TiF₄B significantly affected FS (p = 0.004). The DC for TiF₄P was not significantly different from that of CL, and higher than that of TiF₄B. Lower average particle size was observed for TiF₄P at baseline. TiF₄ aqueous solution showed a tendency to agglomerate. TiF₄-containing adhesives did not influence µTBS or failure mode to dentin over time, although FS and DC were affected, especially when TiF₄ was incorporated into the B. TiF₄P presented excellent stability over time.