DENTIN BOND STRENGTH OF DYRACT-CEM

Purpose: To evaluate the influence of provisional cements and of a den tin bonding agent on the adhesion of a self-curing polyacid-modified r esin composite (Dyract Cem) on pressurized human dentin. Materials and Methods: Freshly prepared dentin specimens of human teeth were perfus ed 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 s urface for 24 hours. Only then was Dyract Cem (with or without Prime & Bond 2.0) added onto the dentin after cleaning the dentin surface wit h 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 ad ded for 24 hours. After cleaning with pumice, Prime & Bond 2.0 was app lied 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 val ues were displayed by means of a box plot and they were analyzed stati stically by Mann-Whitney, Kruskal-Wallis or one way ANOVA tests. Resul ts: 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 applicat ion 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 signi ficant 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 a dditional dentin surface treatment.