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Dentin bond strength of Dyract Cem
1University of Zurich, Department of Fixed and Removable Prosthodontics and Dental Material Sciences, Switzerland.
Purpose:
To evaluate the influence of provisional cements and of a dentin bonding agent on the adhesion of a self-curing polyacid-modified resin composite (Dyract Cem) on pressurized human dentin.
Materials And Methods:
Freshly prepared dentin specimens of human teeth were perfused with physiologic saline. Three different types of surface treatment were evaluated. (1) Dyract Cem was applied to freshly prepared dentin without (Group 1.1) or with (Group 1.2) the respective dentin bonding agent (Prime & Bond 2.0) and cured. (2) Freegenol (Groups 2.1 and 2.2) or Temp Bond (Groups 2.3 and 2.4) were applied first on the dentin surface for 24 hours. Only then was Dyract Cem (with or without Prime & Bond 2.0) added onto the dentin after cleaning the dentin surface with pumice. 3) Prime & Bond 2.0 was applied first on the dentin surface and cured. Then Freegenol (Group 3.1) or Temp Bond (Group 3.2) were added for 24 hours. After cleaning with pumice, Prime & Bond 2.0 was applied for a second time on the dentin (= dual application) and finally Dyract Cem was added. As control, a conventional glass ionomer cement (Ketac-Cem Maxicap; Groups 4.1-4.3) was used in a similar way. After 1,500 thermal cycles with constant imitation of intrapulpal pressure, shear bond strengths were measured. Resulting shear bond strength values were displayed by means of a box plot and they were analyzed statistically by Mann-Whitney, Kruskal-Wallis or one way ANOVA tests.
Results:
Lowest and highest mean shear bond strength values were 0.27 +/- 0.42 MPa (Group 2.4; single use of Prime & Bond 2.0 with prior application of TempBond) and 5.84 +/- 3.36 MPa (Group 3.1; dual use of Prime & Bond 2.0 with intermediate application of Freegenol). A clearly significant difference between groups could only be found when a single or dual use of the dentin bonding agent Prime & Bond 2.0 were combined with either Freegenol (Groups 2.1, 2.2 and 3.1; Kruskal-Wallis: P < 0.01) or Temp Bond (Groups 2.3, 2.4 and 3.2; Kruskal-Wallis: P < 0.001) as additional dentin surface treatment.