[Comparisons of meter reading values in 5 electronic measuring devices].

The root apex values given in the manufacturers' introductions of 5 electronic measuring devices were compared with the mean values measured by each device in the following cases: a) The tip of file was at the apical constriction in the experimental tooth model. b) The tip of file was between 0 mm and -2.0 mm from the root apex in the vital teeth and the pulpless teeth. In the experimental tooth model, when the tip of file was at the apical constriction, the mean values measured by each device except EM were lower than the root apex values given in the manufacturers' introductions of each device. In the case of the vital tooth, when the tip of file was between 0 mm and -2.0 mm from the root apex, the mean values measured by EM-S II and EM were similar to the values given in the manufacturers' introductions of these devices, but not to those obtained by the other devices. Measurements of the pulpless tooth by each device revealed mean values lower than the values given in manufacturers' introductions for the root apex.