Clinical Evaluation of Conventional Radiography, Radiovisiography, and an Electronic Apex Locator in Determining the Working Length in Primary Teeth. 
This study's purposes were to: (1) compare the accuracy of conventional radiography (CR), radiovisiography (RVG), and the Root ZX mini apex locator (EAL) in determining the working length in primary teeth; and (2) determine the effect of wet/dry conditions on the accuracy of the EAL.  Twenty-two children (six to 15 years old), with 41 root canals of primary teeth with or without resorption indicated for extraction, were selected.  CR and RVG were used to determine the working length, followed by EAL, according to the manufacturer's instructions in both dry and wet fields (saline).  Following extraction of the teeth, the actual working length was determined under stereo microscope (2X).  The data was tabulated and statistically analyzed using one-way analysis of variance and student's t test.  The highest percentage of accurate working length measurements within the acceptable range of ±0.5 mm were for EAL (95.1 percent), followed by RVG (75.6 percent) and CR (75.6 percent).  There were no statistically significant differences between the three techniques (P>0.05), and the readings obtained by the apex locator were not affected by resorption or the medium (wet/dry).  The Root ZX mini apex locator showed the most promising results, followed by radiovisiography and conventional radiography.