Bond strength to aged CAD/CAM composites and polymer-infiltrated ceramic network using a universal adhesive with or without previous application of a universal primer

To analyse the bond strength to aged CAD/CAM composites and a polymer-infiltrated ceramic network (PICN) after different surface pretreatments and the use of a universal adhesive or universal primer and universal adhesive. Specimens were prepared from CAD/CAM composites (Brilliant Crios, Grandio Blocs, Lava Ultimate, Tetric CAD, Cerasmart270, Katana Avencia, Shofu Block HC) or PICN (Vita Enamic) and artificially aged (5000 cycles, 5–55 °C). The surfaces were left untreated or pretreated by mechanical roughening, aluminium oxide sandblasting, silica coating, or hydrofluoric acid etching (PICN only). The surfaces were further conditioned with a universal adhesive only or a universal primer/universal adhesive (each subgroup n = 12). After application of a composite and further thermal cycling, shear bond strength and failure modes were assessed and statistically analysed by ANOVAs, Weibull statistics, and Chi 2 -test (p < 0.05). In CAD/CAM composites, highest bond strength values were obtained for sandblasting (mean of all subgroups: 15.7 ± 4.5 MPa) > silica coating (13.5 ± 4.1 MPa) > mechanical roughening (11.3 ± 4.5 MPa) > no pretreatment (4.1 ± 2.3 MPa). The use of a universal primer led to a significant, albeit small increase of bond strength (11.9 ± 6.0 > 10.4 ± 5.6 MPa). In PICN bond strength was: hydrofluoric acid etching (15.2 ± 4.0 MPa) > silica coating (12.2 ± 4.3 MPa) > sandblasting (11.6 ± 5.3 MPa) > mechanical roughening (10.9 ± 7.2 MPa) > no pretreatment (2.8 ± 2.7 MPa). The application of a universal primer led to a significant increase of bond strength (13.5 ± 6.3 > 7.6 ± 5.0 MPa). Adhesion to aged CAD/CAM composites mainly requires adequate micromechanical retention, while PICN additionally requires the use of a universal primer. • Repair of CAD/CAM composites and PICN is possible. • Repairing CAD/CAM composites requires sandblasting. • Repairing PICN requires surface pretreatment and the use of a universal primer.