Bond Strength to Lithium-Disilicate Ceramic after Different Surface Cleaning Approaches

Purpose: To evaluate the effect of different lithium-disilicate (LiSi) glass-ceramic surface decontamination procedures on the shear bond strength (SBS) to resin cement. Materials and methods: Seventy CAD/CAM LiSi ceramic specimens (IPS e.max CAD, Ivoclar) were cut and sintered. Fifty specimens were treated with 5% hydrofluoric acid (HF) for 20 s, while 20 were left untreated. All 70 specimens were then contaminated with human saliva and try-in silicone paste. The following surface cleaning methods were investigated (n = 10): C: water rinsing (control); PA: 37% H3PO4 etching for 20 s; E: 70% ethanol applied for 20 s; CP: cleaning paste (Ivoclean, Ivoclar) brushed for 20 s; HFSEP: self-etching ceramic primer (Monobond Etch&Prime, Ivoclar) rubbed for 20 s; HF: 5% HF applied for 20 s or no HF etching prior to contamination; SEP: self-etching ceramic primer rubbed for 20 s and no HF etching prior to contamination. Composite cylinders were created and luted with an adhesive resin cement to the decontaminated surfaces. After storage for 24 h at 37°C, the SBS test was conducted. Two fractured specimens per group were observed under SEM to perform fractographic analysis. The data were statistically analyzed with p set at <0.05. Results: The type of surface cleaning approach influenced bond strength (p < 0.001). HFSEP, SEP, and HF attained higher SBS (p < 0.001) compared to other groups. None of the approaches were able to completely remove contaminants from the ceramic surfaces. SEM images showed residual traces of contaminants on CP-treated surfaces. Conclusions: The self-etching ceramic primer enhanced bond strength to contaminated LiSi ceramic surfaces, irrespective of previous treatment with hydrofluoric acid.

Purpose: To evaluate the effect of different lithium disilicate (LiSi) glass-ceramic surface decontamination procedures on the shear bond strength (SBS) to resin cement. Materials and Methods: Seventy CAD/CAM LiSi ceramic specimens (IPS e.max CAD – Ivoclar) were cut and sintered. Fifty specimens were treated by 5% hydrofluoric acid (HF) for 20s, while 20 were left untreated. All 70 specimens were then contaminated with human saliva and try-in silicone paste. The following surface cleaning methods were investigated (n=10): G1) water rinsing (control, C); G2) 37% H3PO4 etching for 20s (PA); G3) 70% ethanol applied for 20s (E); G4) Ivoclean (Ivoclar) brushed for 20s (IVO); G5) Monobond Etch&Prime rubbed for 20s (MEPHF); G6) 5% hydrofluoric acid applied for 20s (HF)-no HF etching prior to contamination; G7) MEP rubbed for 20s (MEP)-no HF etching prior to contamination. Composite cylinders were created and luted with an adhesive resin cement to the decontaminated surfaces. After storage for 24 h at 37 °C the SBS test was conducted. Two fractured specimens per group were observed under SEM to perform fractographic analysis. Data were statistically analyzed (p<0.05). Results: The type of surface cleaning approach influenced bond strength (P<0.001). MEPHF, MEP and HF attained higher SBS (P<0.001) compared to other groups. None of the approaches were able to completely remove contaminants from the ceramic surfaces. SEM images showed residual traces of contaminants on the IVO-treated surfaces. Conclusions: The self-etch ceramic primer was able to enhance bond strength to contaminated LiSi ceramic surfaces, irrespective the previous treatment with hydrofluoric acid.