In vitro evaluation of the film thickness of self-etching resin cements.

The aim of this study was to evaluate the film thickness of selfetching resin cement. The following materials were used: Group1, Relyx U100 (3M /ESPE); Group 2, BisCem (Bisco); Group 3, Max Cem (Kerr); Group 4, Set (SDI) and Group 5, Relyx ARC (3M/ESPE) as control. Two 5.4 x 76.2 x 1 mm glass slides were marked in the center to identify the area where the material would be placed. A volume of 0.05 ml was used for each specimen material. After 1, 3 and 6 minutes, a 50 N load was applied for one minute. The thickness of each specimen was then measured using a digital micrometer to the nearest 1 μm; (Digimatic, Mitutoyo Corporation, Japan.). Data were analyzed using ANOVA and Bonferroni's multiple comparison tests. No significant difference was found between the materials tested (p = 0.0921) or material/time interaction (p = 0.0864), but there were differences in the time factor (p = 0.0001). At one minute, the thinnest film was Relyx ARC (control) (14 μm), followed by Relyx U100 (17 μm), and Maxcem and SeT (19 μm). At 3 minutes, Group 5 (control) was also the thinnest film (19 μm), followed by Group 1 (21 μm), Group 3 (25 μm), Group 2 (29 μm), and Group 4 (31 μm). At 6 minutes, Group 4 was the thinnest (34 μm), followed by Group 1 (38 μm), Group 5 (40 μm), Group 2 (41 μm) and Group 3 (42 μm). The film thickness of resin cements was influenced by time and polymerization reaction. The film thickness of self-etching cements was low.