Effect of a novel pretreatment on the microtensile bond strength of universal adhesives with dentin

Background: /purpose: The quality of the hybrid layer is of great importance for dentin bonding. The purpose of this study was to develop a novel copper-based pretreatment and investigate the effect of the pretreatment combined with universal adhesives on the dentin bond strength. Materials and methods: Etch-and-rinse adhesive Single Bond 2 (SB2) and two universal adhe-sives Prime Bond Universal (PBU) and Single Bond Universal (SBU) were selected. The dentin surfaces were pretreated with CuSO4 solution and K2HPO4 solution in turn (Cu-P pretreat-ment), and the adhesive was applied following the manufacturer's instructions. There were four groups of Cu-P pretreatment: HH-Cu (1.5 mol/L CuSO4 + 1.0 mol /L K2HPO4); H-Cu (0.15 mol/L CuSO4 + 0.1 mol/L K2HPO4); L-Cu (0.015 mol/L CuSO4 + 0.01 mol/ L K2HPO4); and LL-Cu (0.0015 mol/L CuSO4 + 0.001 mol/L K2HPO4). The microtensile bond strength (m- TBS) and fracture mode were determined. The dentin surface after pretreatment and the anti-microbial properties of the pretreatment agent were also evaluated. Results: The minimum inhibitory concentration and minimum bactericidal concentration of Cu -P pretreatment were 0.012 mol/L CuSO4 + 0.008 mol/L K2HPO4. Combined with SB2, the H -Cu and L-Cu groups showed a higher m-TBS (P < 0.01), while the HH-Cu group showed a lower m-TBS (P < 0.001), and the LL-Cu group showed a similar m-TBS with the control group without Cu-P pretreatment. Combined with universal adhesives PBU and SBU, the H-Cu and L-Cu groups also showed significantly increased m-TBS (P < 0.01). Conclusion: The copper-based pretreatment in combination with universal adhesives improved the dentin microtensile bond strength. 2022 Association for Dental Sciences of the Republic of China. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons. org/licenses/by-nc-nd/4.0/).