Background:There is a growing interest about electronic apex locators for working length determination. There are several studies dealing with their performance in different conditions.Aims:The aim of this study is to evaluate the accuracy of Root ZX and Raypex 6 in teeth with different apical diameters.Materials and Methods:Actual working length (AWL) of 80 single rooted teeth were determined as 0.5 mm short of apical foramen. The teeth were divided into 4 groups (n = 20). First group (G 0) included teeth with mature apices. Root canals of the other groups (G 32, G 57 and G 72) were enlarged until apical sizes of 0.32, 0.57 and 0.72 mm were obtained. Samples were embedded in alginate and electronic measurements (EM) were performed.Statistical analysis:was achieved with Fisher exact test.Results:Both devices revealed a high rate of success in G 0 and G 32. Their accuracy decreased significantly in G 57 and G 72 groups (P < 0.05). Intra-group results of Root ZX and Raypex 6 were similar (P > 0.05).Conclusions:Root ZX and Raypex 6 are reliable in teeth with mature apices. At foramen diameters exceeding 0.57 mm, their accuracy is susceptible.

The aim of this study is to evaluate the incidence of crack formation while using Reciproc, WaveOne and Twisted File Adaptive with and without ethylenediaminetetraacetic acid (EDTA) gel. Seventy extracted mandibular premolars were included. The teeth were decoronated until roots of 16 mm were obtained. Samples were distributed into seven groups: group 1, no canal preparation (control); other groups were instrumented so; group 2, Reciproc; group 3, Reciproc + EDTA; group 4, WaveOne; group 5, WaveOne + EDTA; group 6, Twisted File Adaptive; group 7, Twisted File Adaptive + EDTA. Roots were horizontally sectioned from 3, 6 and 9 mm from apex and observed under stereomicroscope. The number and the incidence of cracks were recorded and statistically analysed with chi-squared and Kruskal-Wallis tests. Control group did not reveal any cracks. Crack formation with three novel Ni-Ti instruments was similar. Using EDTA gel did not reduce crack occurrence.

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