Effect of the Controlled Delivery of Chelating Agents on the Pulp Tissue Dissolution Ability of Fresh Sodium...

The purpose of this study was to evaluate pulp tissue dissolution ability of sodium hypochlorite (NaOCl) when mixed with tetrasodic etidronate (Na₄HEBP) and disodic ethylenediaminetetraacetate (Na₂EDTA) under controlled flow.

Bovine pulp tissue was extracted from the lower incisors of 10 bovine jaws. Pulp specimens were standardized in size (1 × 3 × 10 mm), blotted dry, and weighed (initial weight [T0]: mean (SD) = 31.98 (1.18) mg). Specimens from the same jaw were randomly assigned to 2 control (n = 3 each) and 4 experimental groups (n = 10 each): NC (negative control/distilled water), PC (positive control/6%NaOCl), G1 (3%NaOCl), G2 (3%NaOCl-17% Na₂EDTA), G3 (3%NaOCl-18% Na₄HEBP), and G4 (3%NaOCl-9% Na₄HEBP). Distilled water and NaOCl were provided using a delivery pump under a continuous controlled rate (1 mL/min). A second pump alternately delivered either Na₂EDTA or Na₄HEBP at the same rate with a 30-second programmed interval. Percentage of tissue weight loss was calculated at 2, 5, and 10 minutes (T2, T5, and T10) and compared among groups with analysis of variance. Free available chlorine and pH were controlled at T0 and T10.

No tissue remained in PC at T5. No dissolution occurred in NC. There were no significant differences in the percentage of weight loss among experimental groups at any point of time. Some remnant tissue was found in G3 (1.4% ± 2.4) and G4 (1.6% ± 2.3) at T10, whereas nothing was left in G1 and G2.

The controlled delivery of Na₂EDTA and Na₄HEBP did not alter tissue dissolution ability of NaOCl when fresh solutions were mixed in the root canal.