Influence of acid concentration and etching time on resin cement adhesion to lithium silica-based glass ceramics

Riccardo F. Fonzar, Cecilia Goracci, Michele Carrabba, Chris Louca, Marco Ferrari, Alessandro Vichi

Research output: Contribution to journalArticlepeer-review


Purpose: To evaluate the influence of hydrofluoric acid (HF) concentration and etching time on the micro-shear bond strength (µSBS) of RelyX Unicem 2 to VITA Suprinity (ZLS) and IPS e.max CAD (LD). Materials and Methods: Forty-eight bars were respectively fabricated for ZLS and LD with CEREC InLab MC-XL. For each material, 8 groups were identified with respect to etching time of 20, 40, 60, 120 s and HF concentration of 4.9%, 9.5%. In each group, after etching and silanization, 15 specimens were prepared for µSBS test building-up RelyX Unicem 2 with a specific device. Data were analyzed using Three-Way ANOVA. Failure modes were assessed using an optical stereomicroscope, classified as adhesive, cohesive in resin or ceramic, mixed. Failure modes were statistically analyzed using the Fisher’s Exact Test. One bar per group was prepared for SEM observation of the etched surface. Results: ZLS showed significantly higher bond strengths than LD (p<0.001). Etchant concentration was an influential factor with superior strengths after 4.9% HF etching (p=0.009). Etching time did not significantly affect adhesion (p=0.066). The material-etching interaction was statistically significant (p=0.004). Particularly, for ZLS 4.9% HF etching obtained significantly higher bond strengths than 9.5%. By using 4.9% HF, adhesion was significantly higher on ZLS than LD. Conclusion: Material and HF concentration influenced the adhesion between RelyX Unicem 2 resin cement and lithium silica-based glass ceramics. Etching time was not an influential factor. The use of 4.9% HF for 20 s showed to be the most convenient etching treatment of the intaglio surface
Original languageEnglish
JournalJournal of Adhesive Dentistry
Publication statusAccepted for publication - 10 Sept 2019


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