Effect of gutta-percha solvents on surface microhardness of IRM fillings.

Eighty identical samples of IRM were prepared and embedded in acrylic resin. The samples were polished, rinsed, and divided into experimental groups and controls, 10 specimens each. Each experimental group was treated for 1 or 5 min with one of the following gutta-percha solvents: chloroform, xylene, or halothane. Sterile saline was used as a control. Treatment consisted of pipetting each solvent onto the external IRM surface. The specimens were then sealed in plastic assay tubes for the corresponding exposure periods. At each time period, surface microhardness of the samples was measured using a mini-load hardness tester with a 500 g load for 20 s. It was found that xylene and halothane caused significant reduction in surface microhardness of IRM after 5 min (p < 0.01). Chloroform caused significant reduction in surface microhardness of IRM after 1 min of treatment (p < 0.01). Chloroform caused total dissolution after 5 min of treatment. Saline caused only minor and nonsignificant changes in surface microhardness of IRM.