Surface Conditioning Methods and Their Effects on Micro-Tensile Bond Strength and Micro-Chemical Properties of Glass-Infiltrated Zirconia: An In Vitro Study

BACKGROUND Surface conditioning methods play a critical role in enhancing adhesion by creating micro-mechanical and chemical bonds between resin cement and ceramics. This study aimed to evaluate the effects of different surface treatments on micro-tensile bond strength (MTBS) between resin cement and glass-infiltrated zirconia (GLZR), as well as surface changes in topography, roughness, and elemental properties assessed by energy-dispersive X-ray analysis (EDAX). MATERIAL AND METHODS Thirty GLZR blocks were fabricated and divided into 3 groups (n=10) according to the applied surface treatment: laboratory grit-blasting (LGB), laboratory silica coating (LSC), and hydrofluoric acid etching (HFAE). After treatment, specimens were bonded to composite blocks with resin cement, and MTBS was tested using a universal testing machine. Surface roughness was measured; morphological and elemental changes were examined by scanning electron microscopy (SEM) and EDAX. RESULTS The LSC group exhibited the highest MTBS (28.23±1.53 MPa), followed by the LGB group (20.27±2.33 MPa) and the HFAE group (10.41±1.46 MPa). Surface roughness was highest in the LGB group (Ra=9.34±1.23 μm). SEM analysis revealed prominent crater formation in the LGB and LSC groups, whereas the HFAE group showed minimal topographic change. EDAX indicated increased silica content in the LSC group and reduced zirconia content in the LGB group; these findings were linked to enhanced chemical bonding. CONCLUSIONS Among the tested surface treatments, laboratory silica coating significantly improved both surface chemistry and MTBS, making it the most effective method for strengthening resin-zirconia adhesion.