The effect of specimen dimensions on the flexural strength of a composite resin.

UNLABELLED PUORPOSE: The aim of this study was to evaluate the effect of specimen dimensions on the flexural strength of a composite resin (Heliomolar RO). METHODS The different dimensions tested - length x width x height (mm) were: 25x2x4; 25x2x2 (ISO 4049); 15x2x2; 10x2x2 and 10x2x1. Light-curing was performed at 600 mW/cm² for 40s, three times along the 25mm specimens, twice along 15mm specimen and once for the 10mm specimens. Specimens of all dimensions were light-cured on both surfaces, or only on one side. In the latter, the load was applied on the irradiated side or on the opposite one. RESULTS It was shown that the flexural strength was not affected by specimen length. When light-curing was performed on both surfaces, similar flexural strength values were obtained for any dimension. Despite the number of irradiated surfaces, specimens with a height of 1mm also obtained similar values. On the contrary, specimens with a height of 4mm, exposed only on one surface, reached the lowest strength. CONCLUSION The use of specimens with lower dimensions can lead to flexural strength values similar to the ones obtained with standardized specimen (ISO 4049), with the advantage of demanding less amount of material and being less time consuming.