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

Abstract

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.