Stickiness prior to setting of some light cured resin-composites

Objectives. To describe and evaluate a method for deriving a laboratory measure of stickiness, and to compare a set of dental resin-composites by this procedure. Materials and methods. Twelve commercial resin composites were selected. Each material was placed in a cylindrical mold (phi = 6.1 x 2.2 mm(2) depth) held either at 23 or at 37 C. A flat-ended stainless-steel instrument was placed onto the surface of the unset sample with a force 350 g. After 2 s it was moved vertically at 2 cm/s. This caused a sticky composite to be elevated to a maximum height between 0.2 and 1.8 mm until detachment from the instrument occurred. The elevated material was immediately solidified by light curing at 600 mW/cm(2) for 40 s. These elevated profiles were mapped for both height and projected area of elevation. An instrument was constructed for this purpose in our laboratories. Both the projected heights and areas were evaluated as potential measures of stickiness. One-way ANOVA and Duncan's multiple range test were used for statistical analysis. Results. Projected heights ranged from 0.2 to 1.8 mm and projected areas of elevation ranged from 4.0 to 23.9 mm(2). The greatest values were found for microfine anterior composites (Silux plus, Filtek Al 10). There was a significant difference (p < 0.05) between the material (SX) with the highest stickiness and all of the others. The set of profile height and area values were found to be strongly correlated (r(2) = 0.9600). Significance. Once inserted and the load removed, the ideal material stays in place. This is generally assisted by an increase in viscosity and a decrease in stickiness. The stickiness test described is original and may prove to be useful as a standard test method for characterizing the handling stickiness of resin composite materials. (C) 2003 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved.