TiF₄ Incorporated Into Self-etching Adhesive: Dentin Bonding at Different Depths and Times

Objectives: The aim was to evaluate the bond strength to superficial (SD) and deep dentin (DD) after the use of 2.5% or 4% titanium tetrafluoride (TiF4) in aqueous solution (AS) as a pretreatment or when incorporated to the primer (P) of a self-etching adhesive system (Clearfil SE Bond / CL) after 24 hours or 180 days.
Methods: Fifty molars were longitudinally sectioned. Dentin slices were demarcated into two zones (SD and DD). The slices were separated (n=10): CL; ASTiF4 2.5% + CL; ASTiF4 4% + CL; TiF4 2.5% incorporated into the P; TiF4 4% incorporated into the P. Microcylinders were placed at the SD and DD, followed by filling with composite resin. After 24 hours or 180 days, microshear bond strength tests were performed. The fracture mode was recorded. The degree of conversion (DC) of the adhesive system with and without incorporation was evaluated by FTIR.
Results: One-way ANOVA showed no significant differences among groups regarding DC (p = 0.9134). The analysis of mixed models in a split-plot design with subdivided parcels showed that there was significant effect of the triple interaction among factors concentration of TiF4*solution*storage time (p=0.0075). Bond strength of TiF4 4% incorporated into the P was significantly higher at 180 days evaluation for both depths. There were higher bond strength values in SD than in DD (p=0.0105) for all treatments in both times. The failure mode showed mostly adhesive failures, regardless of depth and time (p=0.3746).
Conclusions: The bond strength in both times in different depths was not affected by treatments. There was higher bond strength to SD when using the 2.5% or 4% TiF4 in AS or incorporated into the P. The failure modes observed were adhesive, although there is a higher prevalence of early failures when using the aqueous solution of TiF4 4% as dentin pretreatment in deep dentin.