Film thicknesses of recently introduced luting cements

Statement of problem: A luting cement must maintain a minimum film thickness over a sufficient period of time to allow seating of indirect restorations. The performance of newer luting cements in this regard has not been evaluated. Purpose: The purpose of this study was to compare the film thicknesses of 6 luting cements, 2 resin-modified glass ionomer (FujiCEM and RelyX Luting Plus), 2 composite resin (Panavia 21 and RelyX ARC), and 2 self-adhesive resin (Maxcem and RelyX Unicem) cements, over 3 minutes. Material and Methods: The film thickness (μm) of each cement (n=7) was determined at room temperature at 1, 2, and 3 minutes after the start of mixing, according to the testing method set forth in ISO Standard 9917. Means of all cements were compared at the 2-minute interval, and means at the 1- and 3-minute intervals for each were compared to the mean for the same cement at 2 minutes, using 1-way analyses of variance (ANOVA) and Tukey-Kramer multiple comparison tests (α=.05). Results: Except for 1 resin-modified material at 3 minutes, a point beyond its specified working time, all materials produced film thicknesses under 30 μm at 3 minutes and under 26 μm at 2 minutes. Conclusions: All of the materials tested meet the ISO standard of 25-μm maximum film thickness for up to 2 minutes after mixing. (J Prosthet Dent 2009;101:189-192).