Influence of Fit-checking Material and Cleaning Protocols on the Bond Strength of Lithium Disilicate Glass-ceramics
To evaluate the bond strength of a resin luting agent to a lithium disilicate glass-ceramic after the use of different fit-checking materials and cleaning protocols. Two hundred and forty-two (242) ceramic specimens were etched with 5% hydrofluoric acid for 20 seconds and distributed into 22 groups (n=10), in total. Four (4) groups were created based on fit-checking material and that had no following cleaning protocol: no fit-checking material used (control group); articulating paper; articulating spray; and fit-checker liquid. For each fit-checking material (3), 6 cleaning protocols were tested creating an additional 18 groups (n=10): air/water spray; 70% alcohol (ethanol); acetone; 35% phosphoric acid; 5% hydrofluoric acid; and a commercially available cleaning paste (Ivoclean, Ivoclar Vivadent). Silane and bonding resin were applied to all ceramic surfaces. Resin luting agent cylinders (1 mm in diameter) were created using silicone matrices, light-cured, and specimens were stored in deionized water at 37°C for 24 hours. Microshear bond strength test (μSBS) was performed on a universal testing machine (DL 500, EMIC) at a crosshead speed of 1 mm/min until failure. Results were statistically analyzed using ANOVA and Tukey’s test (α=0.05). Articulating paper and fit-checker liquid, when not properly removed, negatively affected the bond strength (p<0.05). None of the tested cleaning protocols were effective for articulating paper (p<0.05). There was no significant difference in bond strength after the cleaning protocols between articulating spray and fit-checker liquid when compared to the control group (no contamination) (p>0.05). The cleaning protocols tested can effectively restore the bond strength of resin luting agents to lithium disilicate ceramics that were exposed to articulating spray or fit-checker liquid. The use of articulating paper is not recommended for fit-checking indirect lithium disilicate restorations.SUMMARY
Objectives
Methods and Materials
Results
Conclusion
Ceramic specimen treatment and fit-checking materials use. (A) Smooth flat surface of lithium disilicate glass-ceramic; (B) application of 5% hydrofluoric acid; (C) using a microbrush to spread the gel uniformly on the surface; (D) contamination with articulating paper; (E) contamination with articulating spray; and (F) contamination with fit-checker liquid.
Different cleaning protocols. (A) Air/water spray; (B and C) alcohol 70%; (D) acetone; (E and F) 35% phosphoric acid; (G) 5% hydrofluoric acid; and (H and I) cleaning paste (Ivoclean).
Representative SEM images of evaluated groups. (A) Control group (not contaminated); (B) contaminated with articulating paper; (C) contaminated with articulating spray; and (D) contaminated with fit-checker liquid.
Representative SEM images of ceramics contaminated with articulating paper after different cleaning protocols. (A) Air/water spray; (B) alcohol 70%; (C) acetone; (D) 35% phosphoric acid;(E) 5% hydrofluoric acid; and (F) cleaning paste (Ivoclean).
Representative SEM images of ceramics contaminated with articulating spray after different cleaning protocols. (A) Air/water spray; (B) alcohol 70%; (C) acetone; (D) 35% phosphoric acid; (E) 5% hydrofluoric acid; and (F) cleaning paste (Ivoclean).
Representative SEM images of ceramics contaminated with fit-checker liquid after different cleaning protocols. (A) Air/water spray; (B) alcohol 70%; (C) acetone; (D) 35% phosphoric acid; (E) 5% hydrofluoric acid; and (F) cleaning paste (Ivoclean).
Contributor Notes
Clinical Relevance
Articulating spray and fit-checker liquid are viable options and should be encouraged for indirect restoration fit-check (instead of articulating paper) since these materials can be properly removed from a lithium disilicate surface before bonding procedures.