It was the purpose of this study to determine the sealing ability of 2 commercially available calcium hydroxide-containing root canal sealers, CRCS and Sealapex. One hundred sixty single-rooted human teeth were used. The clinical crowns were removed and the roots were cleaned mechanically and by immersion for 24 h in 5% sodium hypochlorite. The root canals were then instrumented to size 80 at the apical foramen and the roots were sterilized by gamma-radiation. Under aseptic conditions the root canals were filled with a gutta-percha master cone size 70 and Sealapex (48 roots), CRCS (48 roots), and a zinc oxide-eugenol type sealer, Roth 801 (50 roots). The coronal aspects of the root canals were then sealed with zinc oxide-eugenol cement. In order to bring the roots and root filling materials in contact with tissue and tissue fluids, the roots were implanted subcutaneously in rabbits for 90 days and 1 year. Leakage as demonstrated by penetration of India ink was evaluated using a stereomicroscope. The best results were obtained with CRCS. Significantly less leakage occurred with both calcium hydroxide-containing sealers than with the traditional zinc oxide-eugenol sealer.

The effect of low current, sub‐sensation transcutaneous electrical nerve stimulation on pain threshold and pain tolerance level of human teeth subjected to stimulation with an electrical pulp tester was studied. Electrodes were attached to the patients via a patch between the thumb and first finger and a damp cotton roll in the vestibule over the apex of the tooth to be tested. No significant differences between the values for the baseline, experimental and placebo pain perception thresholds were found. Nor were significant differences found between the average experimental and placebo values concerning pain tolerance level. However, in 1 individual the pain tolerance level was not reached at the highest level of stimulation from the electrical pulp tester.