Long-term enhancement of bond strength to zirconia using a modified tribochemical treatment

This study proposed air-abrasion (AA) and additional firing techniques to improve the bond strength of resin cements to 4Y-PSZ zirconia (ZIRC). ZIRC plates (Katana STML) were obtained and submitted to six surface treatments (n = 15): Control 1: AA using Al2O3 particles (50 µm) + Clearfil Ceramic Primer + Tooth Primer and Panavia V5 (Kuraray Noritake); Control 2: Al2O3 particles + Scotchbond Universal and RelyX Ultimate (Solventum); Control 3: CoJet Sand particles (30 µm) (CO) + silane (SI) + bonding resin (BR) (CO–SI–BR); Control 4: CO + ultrasonic cleaning (UC) + SI + BR (CO–UC–SI–BR); Control 5: CO + additional firing (AF) at 800 °C + SI + BR (CO–AF–SI–BR), and Control 6: CO–AF–UC–SI–BR. For experimental groups, the RelyX/ARC resin cement (Solventum) was used. Samples for the shear bond strength (BS) test were stored in distilled water at 37 °C for 24 h and 1 year before testing. BS data were analyzed by two-way analysis of variance and Tukey post hoc test (α = 0.05). Additionally, CoJet-Sand particles and CO-treated ZIRC surfaces were characterized using energy-dispersive X-ray spectroscopy analysis. CO particles impregnated the silicon chemical element on the ZIRC surface; however, UC was able to remove it. When CO ZIRC was subjected to AF, UC did not remove silicon. CO–AF–SI–BR and CO–AF–UC–SI–BR groups increased BS (p < 0.05), which remained stable after one year. Controls showed intermediate results, and CO–SI–BR and CO–UC–SI–BR exhibited the worst BS outcomes (p < 0.05). AF of CO air-abraded ZIRC did not allow displacement of silicon from the ZIRC surface after UC and yielded higher and stable BS results.