Bonding of resin cements to a metal substrate: influence of pretreatment on the adherence energy.

Abstract

The adherence of resin cements to restoration as well as tooth structure is of prime importance for the longevity of cemented restorations. It was the aim of the study to investigate the effect of an acid and a base primer on (i) surface polarity of a nonprecious alloy and on (ii) adherence energy of resin cements bonded to the alloy. The beams were pretreated with a 3% acetone solution of either maleic acid or N,N-diethanol-p-toluidine, and the solvent evaporated. The polarity was determined by means of measurements of contact angles. The adherence energy was measured by means of the wedge test, according to which 2 beams were glued together with the resin cement. A wedge was introduced between the joined beams to create a fissure, and on the basis of the length of the fissure, the adherence energy was calculated. It was found that the polar component of the surface free energy of the alloy increased as a consequence of the pretreatments. The results also showed that the pretreatments gave rise to an increase in adherence energy of 11-15 J/m2, equivalent to relative increases of 22-54%. The observed increases in adherence energy may be due to an increase in polar interactions at the interface between adhesive and substrate.