Effect of repeated vertical loads on microleakage of IRM and calcium sulfate-based temporary fillings

Temporary fillings are commonly used to seal endodontic access cavities bet ween visits. IRM and Cavidentin were selected to represent two widely used groups of temporary filling materials. The first is a reinforced zinc oxide -eugenol preparation that is mixed at chairside, whereas the second is a re ady-to-use calcium sulfate-based material that gained popularity due to its convenience of application. The seal provided by the aforementioned materi als was studied using a radioactive tracer quantitative assay. When compare d as passive temporary filling, the two provided a similar quality of seal. However, when subjected to repetitive "occlusal" cyclic loading of 4 kg, I RM was clearly superior to the calcium sulfate-based material. Whereas IRM maintained a reasonable seal, the calcium sulfate-based fillings deteriorat ed and lost the ability to seal. These results suggest that even though cal cium sulfate-based materials may be useful when not subjected to any occlus al forces, IRM should be preferred whenever occlusal loads may be applied. Furthermore it is demonstrated that testing such materials for microleakage with no reference to mastication forces may be of limited value.