The aim was to prepare experimental adhesive (EA) with ZrO2 nanoparticles (ZEA) and without it; and its interaction with dentin conditioned with photodynamic therapy (PDT), etch and rinse, and Er, Cr: YSGG laser (ECL). Methods consisted of the scanning electron microscope (SEM), energy dispersive X-ray (EDX), shear bond strength (SBS) failure mode, and rheological property analysis. The methods were employed to assess bond integrity; the shape of ZrO2 NPs and interfacial dentin and adhesive interaction. Ninety premolar teeth were collected and pre-bonding, conditioning of dentin was performed utilizing phosphoric acid (H3PO4), photodynamic therapy (PDT), and ER-CR-YSGG laser (ECL). The teeth were set to form bonded specimens using two adhesives EA and ZEA. The microscopic imagery of ZrO2 revealed irregular-shaped, non-edged particles. EDX analysis revealed Zr to be 75.7% whereas, O2 by weight was 25.3%. The highest SBS was demonstrated in dentin conditioned with etch and rinse and ZEA (19.05 ± 0.13 MPa). Whereas, the lowest SBS was observed in dentin surface treated with PDT and EA (12.25 ± 0.14 MPa). Most of the reported failure modes were adhesive. Rheological analysis revealed that with increasing frequencies the viscosities of adhesives were reduced. The presence of 10% ZrO by weight in adhesive improves SBS of restoration and this improvement in bond values is statistically significant compared to EA. Bond values may be influenced by surface treatment of dentin.
Keywords: Cr: YSGG; Er; Scanning electron microscopy; dental adhesive; photodynamic therapy; zirconium oxide.