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.

Adhesiveness↗

PubMedDate not supplied

A comparison of accuracy in seating and gap formation for three inlay/onlay techniques.

The accuracy (fit) of MOD inlays of three brands of composite resin was determined by measuring the axial discrepancy (marginal opening in the approximal area). The axial discrepancy varied between 17 and 121 microns. Directly manufactured inlays were more accurate (axial discrepancy: 17-26 microns) than indirectly manufactured inlays (axial discrepancy: 40-121 microns). Inlays of a microfilled resin, SR-Isosit, were less accurate than inlays of two hybrid materials, Brilliant and Estilux Posterior C VS (axial discrepancy: 121 microns vs 44 and 41 microns respectively). There was a tendency for 24-hour-old inlays to be less accurate than 10-minute-old inlays. The formation of marginal gaps due to contraction of the resin cement was assessed in a light microscope on cemented single-surfaced inlays. Gaps were not formed when enamel margins were etched or dentin margins treated with a dentin-bonding agent of high efficacy. Gaps (2.4-5.6 micron) were formed, however, at untreated dentin margins and at margins treated with dentin-bonding agents of low efficacy.

Composite Resins↗