Influence of ns-Nd:YAG laser surface treatment on the tensile bond strength of zirconia to resin-matrix cements

Abstract

The main aim of this study was to assess the effect of ns-Nd:YAG laser structuring over zirconia green compacts on the adhesion of sintered zirconia to resin-matrix cements. Zirconia (3Y-TZP) compacts were divided according to the type of surface modification: GB – alumina grit-blasted sintered specimens; G8L – laser structured zirconia green compacts (square pattern 8 lines); G16L - laser structured zirconia green compacts (square pattern 16 lines); G8L/GB – alumina grit-blasted G8L specimens after sintering. Specimens of same group were cleaned, cemented using a dual cure resin-matrix cement and aged in distilled water for 24 h (37 °C). Afterwards, the tensile bond strength was measured using a universal test machine. Specimens were analyzed by field emission guns scanning electron microscopy (FEGSEM) and white light interferometry (WLI). Laser-structured surfaces showed higher roughness values and improved morphological aspects for adhesion to resin-matrix cements. Higher tensile bond strength mean values of zirconia to resin-matrix cements were recorded for G8L (16.7 ± 3.8 MPa) and G16L (13.6 ± 3.0 MPa) groups when compared to those recorded for ordinary grit-blasted zirconia surfaces to resin-matrix cements (10 ± 3.1 MPa). The highest tensile bond strength results were recorded for the G8L/GB group (24.2 ± 7.6 MPa). The laser texturing of green zirconia surfaces promoted an increase in roughness and changes in morphological aspects of sintered zirconia for improved adhesion to resin-matrix cements.