Exploring how surface treatments affect the bond stability of lithium disilicate ceramic to resin cement during...

This study evaluated how different surface treatments affect the bond strength of resin cement to lithium disilicate ceramic subjected to try-in. Lithium disilicate (IPS e.max CAD) slices were randomly assigned to 5 experimental groups based on surface treatment protocols with 5% hydrofluoric acid (HF) and silane (SIL) application timing: HF PRE + SIL POST (HF before and SIL after), HF SIL PRE (both HF and SIL before), HF SIL POST (both HF and SIL after), HF SIL PRE + SIL POST (SIL reapplied after), and HF SIL PRE + HF SIL POST (re-treated). Two control groups were included: CTRL+ (no try-in) and CTRL- (no cleaning step after try-in). Resin cement cylinders (n= 56) were bonded and tested for microshear bond strength after 24 hours (baseline) or after 210 days + 25,000 thermal cycles. At baseline, no significant differences were found. After aging, the re-treated groups had the highest bond strength, while the control groups had the lowest. Intermediate results were observed in HF SIL PRE, HF SIL POST, and HF PRE + SIL POST. Try-in remnants were found on HF SIL PRE, and re-etching led to significant matrix dissolution. Post-try-in silane application created a surface layer on the etched ceramic. Cleaning after try-in is crucial for long-term adhesive behavior, regardless of the surface treatment protocol. Applying silane before try-in acts as a protective layer while reapplying silane after try-in further enhances adhesive stability.