Comparative analysis of the composition, viscosity and efficacy of 17% EDTA solutions in endodontic practice

INTRODUCTION. Smear layer removal remains a mandatory step of root canal chemomechanical preparation. However, commercial preparations based on ethylenediaminetetraacetic acid (EDTA) differ in their actual composition, salt form and physical properties, which is not reflected in the labelling and is not taken into account when selecting an irrigation protocol.

PURPOSE. To compare the composition, kinematic viscosity and smear layer removal efficacy of three commercial preparations labelled as 17% EDTA solutions at different temperatures and exposure times.

MATERIALS AND METHODS. Edenta (MedStandard), MD-Cleanser (Meta Biomed) and Edetal (Omega Dent) were studied by thin-layer chromatography, dry residue, complexometric titration, infrared spectrometry, gas chromatography-mass spectrometry, atomic absorption spectrometry and flame photometry. Kinematic viscosity was measured with a VPZh-4 capillary viscometer at 28, 45 and 60°C. Dentine morphology was assessed by scanning electron microscopy (LEO-1430 VP) after 1, 2, 3 and 5 min of exposure at room temperature and at 45°C.

RESULTS. The actual EDTA content was 17.1% in MD-Cleanser, 10.2% in Edenta and 9.3% in Edetal, i.e. two of the three preparations did not match the declared concentration. Kinematic viscosity at 28°C differed more than sevenfold (0.864 cSt for MD-Cleanser versus 6.41 cSt for Edetal) and decreased with rising temperature in all samples. Complete smear layer removal without signs of erosion was achieved by Edenta after 1 min at 45°C and by MD-Cleanser after 2 min at room temperature, whereas Edetal failed to remove the smear layer within 3 min at room temperature.

CONCLUSION. The declared 17% concentration is not a sufficient characteristic of an EDTA preparation. The actual active substance content, salt form, excipients and solution viscosity determine both the time required for smear layer removal and the threshold beyond which dentine erosion develops.

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