Dentine decalcification and smear layer removal by different ethylenediaminetetraacetic acid and 1‐hydroxyethane‐1,1‐diphosphonic acid species

Aim To compare solutions of di‐ and tetrasodium ethylenediaminetetraacetic acid ( EDTA ) and 1‐hydroxyethane‐1,1‐diphosphonic acid ( HEDP ) regarding their ability to solubilize calcium from dentine and remove smear layer. Methodology Solutions with a molarity corresponding to that of 17% Na 2 EDTA ( pH adjusted to 8.5) were prepared by dissolving Na 2 and Na 4 salts of HEDP (etidronate), or Na 4 EDTA in deionized water. Standardized root dentine discs covered by a smear layer were prepared from human third molars. These discs ( n  =   10 per group) were immersed in test solutions or phosphate‐buffered saline for 1 min. The dissolved Ca 2+ was determined by atomic absorption spectroscopy, apparently opened dentinal tubules by laser scanning microscopy and automated image analysis. Ca 2+ values were compared between groups by parametric, tubular areas by nonparametric methods, α = 0.05. Results Solutions prepared from the tetrasodium salts were alkaline ( pH 11.3–11.4), whilst counterparts made from the disodium salts were acidic. The EDTA solutions dissolved more calcium than the HEDP counterparts ( P  <   0.05); solutions prepared with the disodium salts dissolved more calcium than those made from the tetrasodium salts ( P  <   0.05). There was a high correlation between dissolved calcium and the apparently opened tubular areas (Spearman's ρ = 0.81). Differences between groups regarding opened tubules were similar to those observed regarding the Ca 2+ values, with a slightly reduced discerning power due to high variance. Conclusion Calcium chelation and thus smear layer removal by EDTA and HEDP are influenced by pH .