Adham A. Azim, BDS1,2; Hacer Aksel, DDS1,3;

Title:

Comparison of sodium hypochlorite extrusion by five irrigation systems using an artificial root socket model and a quantitative chemical method

Adham A. Azim, BDS1,2; Hacer Aksel, DDS1,3;

M. Margaret Jefferson1; and George T.-J. Huang, DDS MSD, DSc1,*

Supplemental materials

Examination of sample spectra

The absorbance spectra of the samples showed the characteristic features of the taurine-monochloramine spectrum with a peak at 252 nm and were similar to those of the standards (1) Comparison of the spectra with standards showed thatthe measured absorbance at 252 nm in the samples was due to taurine-monochloramine and not to other UV-absorbing materials such as proteins.

Validation of Method

The taurine-monochloraminemethod used to measure extruded NaOCl in the paper is based on published methods(1) and was validated for this study prior to use. Themethod was validated for measuring NaOClby adding multiple volumes from 1-30 µL of NaOCl into tubes, diluting with taurine and DPBS as described in the methods, and measuring the absorbance at 252 nm.A sample dilution volume was selected to optimize absorbance values for the detection of extrusion volumes in the range of 1-30 µL of the 2.23% NaOCl solution. The volume of the added NaOCl was calculated from the absorbance value, the M extinction coefficient of 429 of taurine-monochloramine at 252 nm, the dilution volume and the irrigantNaOCl concentration. This procedure was repeated three times in preliminary studies and a standard curve was included in each extrusion experiment. The calculated mean volume (± SE) for six 10 µL standards was 10.08 ± 0.33 µL.

To validate the method for extrusion samples, one set of twenty NaOCl extrusion samples was assayed by two methods (252 nm absorbance and the colorimetric Nbs assay that measures oxidation to determine the amount of NaOCl). The extrusion volumes calculated by each method were almost identical.

Reference

1- Thomas EL, Grisham MB, Jefferson MM. Preparation and characterization of chloramines. Methods Enzymol 1986;132:569-585.