Universal adhesive application and curing mode affect shear bond strength and shear fatigue bond strength of self-adhesive resin luting cements to dentin

Objectives: To determine the shear bond strength (SBS) and shear fatigue bond strength (SFS) of self-adhesive resin luting cements (RLCs) to dentin with or without universal adhesive application in different curing modes. Methods: Two self-adhesive RLCs (BeautiLink SA and RelyX Universal Resin Cement) were used with or without universal adhesive application. A conventional RLC system (Panavia V5) was used for comparative analysis. Thirty-six specimens were used for each test group: 12 for the SBS and 24 for the SFS tests. Stainless steel rods were bonded to human dentin with and without the light curing of RLC paste. For the SBS test, the bonded specimens were loaded to failure. For the SFS test, repeated subcritical load was applied to the specimens. The flexural strength of the RLCs in different curing modes were also determined. Analysis of variance followed by Tukey's honestly significant difference test, was used for SBS, and a modified t-test with Bonferroni correction was used for SFS (α = 0.05). Results: The SFS results showed a similar trend to the SBS results. The self-adhesive RLCs alone showed significantly lower SFS values in the self-cure mode than in the dual-cure mode. The dual-cure mode triggered higher flexural strength than the self-cure mode. Conclusion: The universal adhesive combined self-adhesive RLCs showed significantly higher bond effectiveness than self-adhesive RLCs alone. Significance: The self-adhesive RLCs combined with universal adhesive may enhance interlocking and chemical bonding. However, light irradiation of the RLC paste remains essential to ensure optimal bonding effectiveness.