Shear bond strength of self-adhesive resin cement to 3D-milled resin treated with universal adhesive

Objective: To investigate the influence of 3D-milled composite resin surface pre-treatment with universal adhesive to shear bond strength (SBS) of self-adhesive resin cement. Material and Methods: 45 samples from hybrid CAD-CAM resin blocks (Brilliant Crios, Coltene, Altstätten, Switzerland) were cut with 15 × 10 × 1.5 mm and divided into 3 groups (n=15) according to resin surface pre-treatment: OC group – One Coat 7.0 universal adhesive and SoloCem self-adhesive resin cement (Coltene, Altstätten, Switzerland); OCA group – One Coat 7.0 chemically activated and SoloCem; SC group (control) – SoloCem, without resin surface pre-treatment. The samples of each group were divided into 3 subgroups (n=5) according to period of aging in distilled water at 37 °C until theSBS test: 1h (baseline); 7 days; and 14 days. SBS test was performed by universal testing machine (5566A, Instron; Massachusetts, USA), operating with 0.5 mm/min speed and 1k-N weight. A stereomicroscope was used to investigate failure pattern. The statistical analysis was performed with two-way ANOVA followed by Tukey tests (α = 0.05). Results: OC and OCA groups showed greater SBS than SC-control group (p < 0.05) in all periods analysed. SC group showed a significantly SBS increase after 7 days which remained unchanged after 14 days. Adhesive failures were associated with SC group, and some mixed failures with OC and OCA groups after 7 e 14 days. Conclusion: The 3D-milled composite resin surface pre-treatment with an adhesive allowed best SBS of self-adhesive resin cement. KEYWORDS Composite resins; Computer-aided design; Dental cements; Dentin-bonding agents; Shear strength.