Microtensile bond strength of luting materials to coronal and root dentin

The purpose of this study was to evaluate the microtensile bond strength (muTBS) of two dual-cured resin cements and a glass ionomer cement to coronal dentin versus root dentin.

RelyX Unicem (3M ESPE, St. Paul, MN, USA) and Panavia F (Kuraray Medical Inc., Tokyo, Japan) were the resin cements used and FujiCEM (GC Corp., Tokyo, Japan) was the glass ionomer cement used. Once separated, the labial coronal and root surfaces of six bovine incisors were ground with 600-grit SiC papers to expose middle dentin. Then, the dentin surfaces were treated following the manufacturers' instructions and a 1 mm thick layer of each material was applied to the flattened coronal and root surfaces. Each material was cured following the manufacturers' recommendations and a composite buildup was made over the cured luting materials for testing purposes. After 24 hours in water at 37 degrees C, the teeth were sectioned into 1 mm x 1 mm x 6 mm beams and tested for muTBS. The data were analyzed by one- and two-way analysis of variance and Fisher's Protected Least Squares Differences test (p < .05).

The microTBSs to coronal and root dentin were similar within each cement. Comparing the materials, RelyX Unicem presented the highest muTBS, followed by Panavia F and FujiCEM, respectively (p < .0001).

Although there were differences in muTBS among the materials tested, no significant differences were found between bond strengths to coronal and root substrates.

Since bond strengths of luting materials to coronal and root dentin showed comparable results, there is no need to treat those surfaces differently prior to luting of indirect restorations. Nevertheless, because significant differences existed among the different luting materials, the choice of a luting material should be based on the type of preparation and restoration as well as the need for fluoride release.