Evaluation of accuracy of an electronic apex locator in presence of sodium hypochlorite in primary teeth with and without resorption.

This study compared the accuracy of Root ZX mini apex locator in presence of sodium hypochlorite (NaOCl) in primary molars with and without apical resorption. Sixty-four extracted primary lower molar teeth with 32 root resorption and 32 without resorption were selected. To determine the actual working length (AWL), a K-file was inserted into the root canal until the tip of the file was visible at the major foramen or the resolution level. It was then withdrawn 1 mm. This value was recorded as AWL. The teeth were then divided subgroups (with/without NaOCl). To determine the electronic working length, a Root ZX mini apex locator in canals with/without NaOCl was used. A K-file was inserted into the canal to just beyond the foramen, as indicated by the flashing "APEX" bar, and the electronic working length was determined by subtracting 1 mm from this length. The deviation of the Root ZX mini measurement from the AWL was determined. Student's t -test was used for statistical analysis. In teeth with no resorption, the measurement accuracy rates (within+/-0.5 mm) of non-NaOCl and NaOCl groups were 84.37% and 81.25%, respectively ( p > 0.05); within+/-1 mm, the non-NaOCl and NaOCl demonstrated 100% and 96.87% accuracy, respectively ( p > 0.05). In teeth with resorption, the measurement accuracy rates (within+/-0.5 mm) was 81.25% for the non-NaOCl and 62.50% for the NaOCl, respectively ( p < 0.05). The measurement accuracy rates (within+/-1 mm) of the non-NaOCl and NaOCl was 96.87% and 84.37%, respectively ( p < 0.05). The presence of NaOCl in the root canal affected the accuracy of the Root ZX mini in primary teeth with apical resorption, but not in teeth without resorption.