The investigation of microleakage in root canal therapy. An electrochemical technique.

An electrochemical technique employing zero-resistance ammetry is described for evaluating the quantity, rate, and areas permeated in the canal system of a root-filled tooth by 1 per cent potassium chloride. Single-rooted extracted teeth were root-filled by a vertical condensation gutta-percha technique. The teeth were coated from the cementoenamel junction to 3 mm. from the apex with a stopping-off medium, so that the apical foramen and the accessory canals in the area would play a role, but not the lateral canals in the gingival area. The teeth were placed in a potassium chloride solution. When the potassium chloride permeated the apical seal and reached a mild steel rod placed through the occlusal access opening extending 2 mm. into the coronal end aspect of the canal, corrosion of the steel was established and was measured for quantity and rate. This technique suggests the possibility of another pathway for tissue fluid to effect coronal dentinal discoloration. The technique also suggests a quantitative means of measuring apical sealing procedures.