Strength of Fiber Posts with Experimental TiO[sub.2] and ZrO[sub.2] Particle Bonding—An SEM, EDX, Rheometric and Push-Out Strength Study

The present study aimed to prepare experimental adhesives (EAs): 5 wt.% titanium dioxide (TiO[sub.2] ) adhesive; and 5 wt.% zirconium oxide (ZrO[sub.2] ) adhesive; and analyze their impact on bond integrity of fiber posts to root dentin, and viscosity. The EA was composed of: bisphenol A glycol dimethacrylate (BisGMA); triethylene glycol dimethacrylate (TEGDMA); 2-hydroxyethyl methacrylate (HEMA); and ethyl 4-dimethylamino benzoate and camphorquinone. TiO[sub.2] and ZrO[sub.2] particles were individually incorporated into the EA at 5 wt.%, to form two groups (5% TiO[sub.2] and 5% ZrO[sub.2] ). The adhesives, with particles, were characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy. The bonded interface was evaluated for adhesive–dentin penetration at the interface, using SEM. The study adhesive groups (EA, 5% TiO[sub.2] and 5% ZrO[sub.2] ) were analyzed for rheology and push-out bond strength of the fiber post to root dentin. Data were analyzed using analysis of variance and post hoc comparison. Both TiO[sub.2] and ZrO[sub.2] particles had irregular, non-uniform shapes. The EDX mapping showed the elemental presence of Ti (TiO[sub.2] ), Zr (ZrO[sub.2] ) and oxygen in formulated adhesives. The 5% TiO[sub.2] and 5% ZrO[sub.2] adhesives showed a decrease in viscosity, compared with the EA. Bond strength among the 5% TiO[sub.2] and 5% ZrO[sub.2] adhesives was statistically comparable (p > 0.05), but higher than the control group (10.57 ± 1.45 MPa) (p < 0.05). Reinforcement of the experimental dentin adhesive with 5% TiO[sub.2] or 5% ZrO[sub.2] increased the push-out bond strength of the fiber post to root dentin, in comparison with the EA. Particle-incorporated adhesives (5% TiO[sub.2] and 5% ZrO[sub.2] ) displayed decreased viscosity, compared with the EA (without particles).