The effect of endodontic solutions on resorcinol-formalin paste.

This study determined if any of four endodontic solutions would have a softening effect on resorcinol-formalin paste and if there were any differences in the solvent action between these solutions. Resorcinol, formalin, and zinc oxide were mixed and allowed to set for 30 days. The solutions tested were 0.9% sodium chloride, 5.25% sodium hypochlorite, chloroform, and Endosolv R. Seven samples per solution were tested and an additional seven samples served as controls. Each sample was saturated with one of the solutions and the depth of penetration was tested at 1, 2, 5, 10, and 20 min using a dial strain gauge. At 2 min, sodium hypochlorite and sodium chloride had significantly greater penetration than the other groups (p < 0.0010). Sodium hypochlorite was superior to all other groups after 5 min. This study showed that both sodium chloride and sodium hypochlorite exhibited a significant softening effect within 2 min.