Currently frequency-dependent type electl´onic apex locators have been widely used to determine the working length in endodontic treatmen. But, accracy of electronic apex locators is controversial. The purpose of this study was to evaluate the accuracy of Root-ZX(Morita Co.Japan) at differnt kinds of conditions of root canals compared with the radiographlc length.
The 40 extracted human anterior teeth with fully formed apices and without any caries were used. The radiographs were taken for working length with the 0.5mm short of #15 K-file tip just visible at the formne under the surgical microscope(Carl Zeiss Com Germany) at 25X. Then the electronic working length were determined with Root-ZX at the different kinds of conditions of root canals according to the presence of electrolyte and Crown-down pressureless technique .
The results were as follows:
1.There was no significant statistical difference in working length between radiograph and root-ZX
2.There was no significant statistical difference in electronic working length between the canal with elctroyte and without elctrolyte.
3.There was no significant statistical difference in electronic working length between the canal without any instrumentation and after Crown-dow pressureless technique.
4.Of the total 40 root canals 85% in Group I,, 92,5T in Group II , 95%, in Group III and 95% in Group IV , using Root- ZX showed coincidence within 0.5mm accuacy companying with the radiography working length
The results showed that the Root -ZX can be use effectively for measuring the working length of root canal after instrumentation with Crown -down presureless technique regardless of the presence of electroyte in root canal.
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