Bond Strength Longitudinal Assessment of Adhesive Systems With Fluoride

Objectives: To determine immediate (48 hours) and late (6 months) dentin bond strength of adhesive systems with fluoride in the composition.
Methods: Bovine incisors (n=120) were divided into two groups according to testing time. Each group was divided into four subgroups (n=10) according to the adhesive system: SFI group: self-etching adhesive with fluoride ( BeautiBond /Shofu Inc., Higashiyama-ku, Kyoto, Japan), immediate testing; SFL group: self-etching adhesive with fluoride, late testing; TFI group: total-etching adhesive with fluoride (FL-Bond II /Shofu Inc., Higashiyama-ku, Kyoto, Japan) immediate testing; TFL group: total-etching adhesive with fluoride, late testing; SSI group: self-etching adhesive without fluoride (Single Bond / self-etching (3M ESPE, St. Paul, MN, USA) immediate testing; SSL group: self-etching adhesive without fluoride, late testing; TSI group: total-etching adhesive without fluoride (Single Bond / total conditioning), immediate testing; and TSL group: total-etching adhesive without fluoride, late testing. A composite resin restoration was built up and specimens stored (48 h). Teeth sticks were obtained and submitted to microtensile test. Fracture patterns were determined through optical microscopy. Bond strength data was analyzed by two-way ANOVA and Tukey (5%) statistical tests. SEM analysis was conducted on selected specimens.
Results: Results showed lower immediate bond strength for the adhesives with fluoride statistically different from the adhesive without fluoride: SFI group (13.0 MPa), TFI group (13.24 MPa), SSI group ((26.18 MPa) and TSI group (21.05 MPa). Bond strength decreased after 6 months for the adhesive without fluoride and showed a slight increase for the adhesives with fuoride: SFL group( (14.75 MPa), TFL group (14.75 MPa), SSL group ((13.99 MPa) and TSL (15.16 MPa). There was no statistical difference among all adhesives after 6 months.

Conclusions: Adhesives with fluoride presented lower immediate bond strength; but bond strength values were basically the same after six months storage for all adhesives.