Effects of Different Surface Treatments on Ceramic Repairs with Composite

Objective: To compare different surface treatments of lithium disilicate-based ceramic on bond strengths to composite. Methods: Lithium disilicate-based ceramic microbars (1 mm × 1 mm × 6 mm) were produced and abraded using diamond (D) or CoJet sandblasting (C), etched using phosphoric acid (P) or hydrofluoric acid (H) and silanised (S). A total of 12 surface treatments were adopted: D, DP, DH, DS, DPS, DHS, C, CP, CH, CS, CPS and CHS. An adhesive resin (XP Bond) was then applied and a composite build-up was placed. All specimens were thermocycled 5,000 times and submitted to microtensile bond strength test (μTBS). Results were analysed using one-way analysis of variance and the Dunnett T3 test. Stereomicroscope and scanning electron microscopy were used to determine the failure modes. Results: Surface roughening, acid etching and silanisation all have a significant influence on the ceramic-composite bond durability. Groups DH (30.7 ± 6.5 MPa), DHS (32.0 ± 8.2 MPa), CH (27.2 ± 4.5 MPa) and CHS (29.2 ± 5.5 MPa) showed the highest μTBS statistically. Groups DS (11.5 ± 3.0 MPa) and DPS (9.7 ± 2.2 MPa) had higher μTBS than groups D (4.5 ± 2.9 MPa) and DP (5.2 ± 3.0 MPa), while groups C (1.7 ± 0.7 MPa), CS (1.7 ± 0.9 MPa), CP (1.7 ± 0.6 MPa) and CPS (1.7 ± 1.1 MPa) showed the lowest μTBS. Conclusion: Hydrofluoric acid etching was effective in improving the bond strength of composite to lithium disilicate-based ceramic, regardless of the method of surface roughening and silanisation. Keywords: Ceramic repair, diamond, hydrofluoric acid, microtensile, silane