Evaluation of Dentaport ZX and Raypex 6 electronic apex locators: an in vivo study.

INTRODUCTION: Raypex 6 is an electronic apex locator (EAL) that has not yet been tested in vivo. The purpose of this in vivo study was to compare the accuracy of two EALs: the Dentaport ZX and the Raypex 6. METHODS: The study involved 36 straight single-rooted teeth. A 10-K file was advanced until the EAL detected the major foramen. The file was fixed in a replaceable pattern of light-cured composite. The apical part of each canal was trimmed to expose the file tip. The distances from the file tips to the major foramen were measured. RESULTS: Wilcoxon's signed Rank test found no significant differences between the Dentaport ZX and Raypex 6 in terms of their abilities to detect the major foramen (P = .52) The Dentaport ZX was accurate 82.35% of the time to ± 0.5 mm and 97.05% of the time to ± 1 mm, whereas the Raypex 6 was accurate 88.22% of the time to ± 0.5 mm and 100% of the time to ± 1 mm. CONCLUSIONS: No statistically significant differences were observed between the performance of the Dentaport ZX and Raypex 6 EALs under the in vivo clinical conditions used in this study.

Evidence for implicit scaling in comparative judgment.

In two experiments, we examined the effects of manipulating the density of stimuli on comparison difficulty in a comparative judgment task. In Experiment 1, subjects was slower at judging the relative size of a pair when the members were adjacent items in the linear order than when the members were separated by items of intervening magnitudes. In Experiment 2, the advantage of choosing the larger rather than the smaller of two large stimuli (e.g., the congruity effect) increased when the linear order included many small items. In contrast, the advantage of choosing the smaller of two small items increased when the linear order included many large items. The applicability of the range-frequency theory (Parducci, 1965) to these results is discussed.