Main

Williams CB, Joyce AP et al. J Endod 2006; 32: 624–627

Root fillings ideally should end at the cementodentinal junction or minor constriction of the canal. Apex locators assist, but do not replace radiographs in identifying this landmark. In this study, 26 canals of 15 teeth with complete apices and planned for extraction were opened.

In each canal, after initial preparation, a file was inserted to a point determined with an apex locator, and cemented in place before taking a radiograph. Teeth were extracted for direct measurement of the distance between file and apex, and radiographic distance was assessed by 6 examiners to the nearest ½ mm.

When the file was beyond the landmark, 24% were correct estimations, 61% were underestimates, and 15% overestimates. When it was short of the landmark, respective scores were 21%, 15% and 63%. The authors conclude that radiographically long files are actually about 1.2 mm longer, and short files are about 0.5 mm longer.