Shear bond strength of a new dentin bonding restorative system

Abstract

A new visible light-cured composite restorative resin, Lumifor, used in conjunction with a dentin bonding agent, Gluma, has recently become commercially available in Europe. The objective of this study was to determine the shear bond strength of the restorative system to dentin. Extracted human permanent molars were stored in 1% chloramine, and the test specimens prepared within 24 h after extraction. The teeth were embedded in cold-cure acrylic and the exposed surfaces ground wet on 600-grit silicon-carbide paper to expose dentin. Gluma Cleanser was applied to the dentin for 30 s and washed for 15 s. Gluma Dentin Bond was applied to dentin for 30 s and blown dry. A split Teflon mold with an inner diameter of 3.5 mm was mounted on the dentin surface in a special device. A thin layer of the low viscosity sealer was applied to the demarcated dentin surface and cured with visible light for 30 s. The composite resin was transferred to the split mold and cured for 2 min. The 75 test specimens were stressed to failure in an Instron machine at a crosshead speed of 0.02 inch.min −1, immeditely after specimen preparation (A), 24 h after specimen preparation (B), 24 h after specimen preparation and subjected to 250 temperature cycles between 5°C and 55°C with a dwell time of 30 s (C), 4 weeks after specimen preparation (D), 4 weeks after specimen preparation and subjected to 250 temperature cycles between 5°C and 55°C with a dwell time of 30 s (E). The shear bond strengths were expressed in MN.m −2, and the data were analyzed by an analysis of variance at the 5% level of significance. The following bond strengths were obtained (mean±SD): A: 8.9±2.3; B: 10.8±3.0; C: 10.8±2.3; D: 10.8±2.1; E: 10.3±1.4. The Gluma/Lumifor system effectively bonds to dentin and the shear bond strength is not adversely affected by storage and temperature cycling.