Influence of silane-containing universal adhesives and separate silanization on lithium disilicate bond strength

The incorporation of silane into universal adhesive systems has been proposed as a strategy to simplify bonding protocols to glass ceramics; however, the effectiveness of this approach remains controversial.

The purpose of this in vitro study was to evaluate the influence of different silane and adhesive application protocols on the bond strength to lithium disilicate ceramic immediately (IM) and after thermocycling (TC).

Lithium disilicate ceramic specimens were etched with hydrofluoric acid and allocated according to the silane application protocol and the adhesive system used. Composite resin cylinders were bonded to the ceramic surface, and microshear bond strength was measured at IM (after 24 hours storage) and after TC (10 000 cycles). Data were analyzed using 2-way ANOVA and the Tukey HSD post hoc test (α=.05). Ceramic surfaces treated with the different protocols were evaluated using a micro-Raman spectrometer for chemical interaction analysis.

Microshear bond strength showed significant effects for both group and time (P<.001). At IM, universal adhesives combined with additional silane application achieved the highest IM values, particularly ABU APS Plus + Prosil and SBU Plus + RelyX CP. After TC, these groups maintained significantly higher bond strengths compared with silane alone or associated adhesives (P<.001). Raman analysis confirmed Si-O-Si and Si-O bond formation in groups treated with silane or silane-containing adhesives, indicating effective chemical interaction with the ceramic surface.

Separate silane application improved the bond strength to lithium disilicate ceramic, regardless of the universal adhesive system evaluated.