Effects of single and double application of immediate dentin sealing techniques on marginal leakage and microtensile bond strength of resin cement

Abstract

Purpose: To evaluate the effects of single and double application of immediate dentin sealing (IDS) techniques on the marginal leakage and microtensile bond strength of resin cement. Materials and methods: Twenty-five extracted third molars were divided into five experimental groups in order to test the marginal leakage and microtensile bond strength of direct bonding, single and double application of IDS techniques using three-step etch-and-rinse (1TE&2TE), and universal (1U&2U) adhesive systems. For the single application of the IDS technique, dental adhesive was applied on the prepared dentin prior to temporary cementation. For the double application, dental adhesive was re-applied after polymerization of the first layer and before temporary cementation. After removing the temporary cementation, the dentin surface was cleaned with an excavator and pumice slurry. Resin cement was used to bond a composite rod to the dentin surface. All specimens were cyclic loaded (50N, 2Hz, 50,000 cycles) and immersed in marginal leakage solutions, and then sectioned into two parts. The first half was cut into small square beams for microtensile bond strength (TBS) testing, while the other half was examined under a light microscope for marginal leakage. Results: The 1TE and 1U groups provided significantly higher uTBS (23.56±3.26 MPa, 21.51±1.30 MPa) than the direct bonding technique (13.56±2.74 MPa) (p < 0.001). There was significant reduction of uTBS (2TE = 21.41±1.59 MPa, 2U = 17.51±2.80 MPa) (p < 0.01) after applying the second layer of adhesive. The marginal leakage was not significantly different in all groups. Conclusion: The two-layer IDS technique using either three-step etch-and-rinse or self-etch universal adhesive did not show any advantage in the uTBS testing or marginal leakage over the one-layer IDS techniques, which showed significantly greater uTBS than the direct bonding technique.