This study evaluated the influence of various universal adhesives (UA's) on the shear bond strength (SBS) of composite repairs to different CAD/CAM-fabricated silicate ceramics and compared silane-containing versus non-silane-containing UA's. 270 rectangular specimens from three CAD/CAM ceramics types CTS (Cerec Tessera HT), IEC (IPS Empress CAD LT), and IXC (IPS e.max CAD LT) were bonded with composite resin (Ceram.x Spectra ST Flow) using UA's: PBA (Prime 5000 cycles 5-55°C). Representative SEM images were analyzed for failure modes. Data were evaluated using the Kruskal-Wallis test with Dunn's correction (α < 0.05). Significant SBS differences were observed across ceramics and UA's. IEC showed the highest SBS values, particularly with CUB (27.09 ± 3.75 MPa) and MBP (24.61 ± 6.36 MPa). Lowest values occurred with IXC + IBU (2.64 ± 3.74 MPa), CTS + SBP (2.05 ± 2.57 MPa), IXC + SBU (0.73 ± 0.56 MPa), and CTS + SBU (0.24 ± 0.53 MPa). IEC differed significantly from CTS and IXC (p < 0.001). Cohesive failures predominated in IEC, whereas IXC and CTS exhibited adhesive failures. UA type, ceramic, and microstructure significantly impact SBS in composite repairs. The selection of UA should be adapted to the type of silicate ceramic to be repaired. In this study, the UA CUB yielded the best results across all ceramic types.
Janson et al. (Mon,) studied this question.