Appearance of chemically treated root canal walls in the scanning electron microscope.

The dissolving effects of seven endodontic solutions on unprepared root canal walls of young intact human premolars were evaluated with the scanning electron microscopy. After incubation at 37 degrees C in distilled water or isotonic saline for 10 min the predentinal surfaces showed no changes as compared with untreated controls. The demineralizers Decal and Largal Ultra had little effect on the organic tissues but caused some decalification where mineralized dentin was exposed. Nelex caused concentration-dependent coagulation of the residual pulp tissue, making typical ring structures on the surfaces. Sodium hypochlorite at 2.5% and 5.0% dissolved most of the predentin, exposing the globular appearance of the mineralizing front. Salvizol produced small globules on otherwise intact surfaces. Dissolution of both the organic and inorganic tissue of the root canal wall would require the combined use of two of the solutions studied.