Abstract
Purpose: To investigate the shear bond strengths (SBS) when indirect resin composite cylinders were bonded to adhesive lined and unlined dentin following the placement of eugenol-containing or eugenol-free provisional restorations. Materials and Methods: One hundred fifty human molar teeth stored in formalin since extraction were prepared to expose a flat dentin surface by grinding with a 600-grit disc. Cylinders of Triad indirect resin composite were then bonded to these dentin surfaces. The teeth were assigned to the following 10 groups (n = 15): (1) resin cement control (Enforce); (2) polyacid-modified resin composite (PMRC) cement control (Dyract Cem); (3) adhesive liner followed by a eugenol-containing provisional restoration (IRM) followed by adhesive bonding with the resin cement; (4) adhesive liner (Prime & Bond) followed by a eugenol-free provisional restoration (temp Bond NE) followed by adhesive bonding with the resin cement; (5) eugenol-containing provisional restoration followed by adhesive bonding with the resin cement; (6) eugenol-free provisional restoration followed by adhesive bonding with the resin cement; (7) adhesive liner followed by a eugenol-containing provisional restoration followed by adhesive bonding with the PMRC cement; (8) adhesive liner followed by a eugenol-free provisional restoration followed by adhesive bonding with the PMRC cement; (9) eugenol-containing provisional restoration followed by adhesive bonding with the PMRC cement; and (10) eugenol-free provisional restoration followed by adhesive bonding with the PMRC cement. After storage, bond strengths were measured by shearing with an Instron testing machine. Results: Mean SBS (MPa) were: resin cement control, 19.9 ± 2.5; PMRC cement control, 14.0 ± 3.5; liner-eugenol-resin cement, 15.5 ± 3.0; liner-noneugenol-resin cement, 19.4 ± 6.8; no liner-eugenol-resin cement, 18.5 ± 4.5; no liner-noneugenol-resin cement, 20.5 ± 4.5; liner-eugenol-PMRC cement, 10.2 ± 3.1; liner-noneugenol-PMRC cement, 11.6 ± 6.0; no liner-eugenol-PMRC cement, 14.3 ± 5.3; and no liner-noneugenol-PMRC cement, 13.1 ± 5.5. A three-way ANOVA (resin liner, provisional restoration and luting cement) demonstrated that significant differences were attributable to the presence or absence of the liner and to the type of cement that was used. Fisher's post hoc test indicated that the mean SBS of the resin cement control group was significantly greater than that of the PMRC cement control group (P = 0.001). This test also pointed out that only when an experimental group involved the placement of a eugenol-containing provisional restoration onto an adhesive lined surface did the mean SBS be- come significantly less than the respective control group.