Tissue-irritation potential of dilute formocresol.

Bacteriologic studies indicate that 50 percent formocresol in propylene glycol is an efficient bactericide. The tissue-irritation potential of this concentration was evaluated in rats. Assessment of the subcutaneous connective tissue reactions to 50 percent formocresol, 100 percent formocresol, and normal saline solution (as a control) indicates that formocresol, when diluted with propylene glycol, is significantly less irritating to the subcutaneous connective tissue of rats. The atraumatic implantation technique also seems to influence significantly the intensity of tissue reaction. Dilute formocresol deserves further study to evaluate its use in clinical endodontics.