Sir,The recent report on “electronic apex locators in the presence of various irrigants” is quite interesting.[1] Mull et al. compared two kinds of apex locators, Root ZX and SybronEndo Mini, and concluded that “Sybron Mini was more accurate with 1% NaOCl and 2% CHX than Root ZX.[1]” Overall, this work gives useful information on selection of proper electronic apex locators. However, there are some additional concerns on dental device usage. First, as a rule in diagnostic medicine, the precision, accuracy, and reproducibility have to be tested. Also, the quality control and assurance is needed. Validation of the analyzers among setting as external quality assurance can help support the reliability of the results.