Comparative Evaluation of Human Pulp Tissue Dissolution by 500-ppm and 200-ppm Hypochlorous Acid and 5.25% Sodium...

The aim of this study was to assess, in vitro, the human pulp dissolution capacity of 500 ppm and 200 ppm of hypochlorous acid in comparison with 5.2% sodium hypochlorite (NaOCl).

Forty pulp tissue samples were standardized to a weight of 9 mg and divided into four groups according to the irrigating solution used: 5.25% NaOCl, 500 ppm hypochlorous acid, 200 ppm hypochlorous acid, and distilled water. Eppendorf tubes carrying 2 mL of the irrigants were taken and the pulp tissue samples were placed in the tubes for the specified time interval: Subgroup A: 30 minutes and subgroup B: 60 minutes. After the designated time interval, the solution from each sample tube was filtered using Whatman filter paper and left for drying overnight. The residual weight was calculated by filtration method. The mean dissolution time for each experimental group at the different time intervals was statistically analyzed.

Mean tissue dissolution increases with an increase in the time period. Approximately 5.25% NaOCl was most effective at both time intervals followed by 500-ppm hypochlorous acid at 60 minutes. Least amount of tissue dissolution was shown by 200-ppm of hypochlorous acid at 30 minutes. Distilled water did not show the ability to dissolve human pulp tissue.

Within the limitations of the study, 5.25% NaOCl dissolved the pulp tissue most efficiently at both time intervals and both concentrations. Human pulp tissue dissolution by hypochlorous acid was found to gradually increase with time and with an increase in its concentration.

With the basic information that hypochlorous acid does have the capacity to dissolve human pulp tissue, further research can be undertaken to assess methods to increase its efficiency. Sooner than later, hypochlorous acid may be able to completely replace the toxic NaOCl in clinical practice, as the irrigant of choice during root canal therapy.