Two different electronic apex locators were used before extraction to
determine working length in 116 root canals belonging to 34 molars. Th
e results were then compared with postextraction working length measur
ements. The determinations were made before and after eliminating the
canal contents and drying the interior. The results showed that 84.8%
and 79.3% of the Odometer, and 89.6% and 88.7% of the Endocater readin
gs for dry and nondry canals, respectively, occurred within the two 0.
5-mm intervals closest to the apical constriction.