# In Vitro Accuracy of Two Different Electronic Apex Locators Under Various Conditions
## 4 Discussion
One study utilized various irrigant solutions, including NaOCl, CHX, ozonated water, EDTA (gel and solution), and distilled water. The findings showed that the use of NaOCl resulted in less accurate results in determining WL compared toCHX. However, there was no statistically significant difference for both EALs when used with NaCl [24]. Regarding the concentration of NaOCl solution, they did not significantly affect the performance of EALs. The best results were obtained with Root ZX II for 2% NaOCl and Dual Pex for 5.25% NaOCl, but without a statistically significant difference [26]. Another study showed the influence of heated and nonheated canal irrigants. The accuracy in the presence of 0.1% Octenidine dihydrochloride and 2% CHX was higher than 5% heated and nonheated NaOCl in both EALs. One paper reported the accuracy of different EALs and the effect of variations in the temperature of 5.25% NaOCl. With a tolerance range of \(\pm\)0.5 mm, Raypex 6 displayed a variable accuracy measuring 95% at 19.4 \({}^{\circ}\)C (\(\pm\)1.5 \({}^{\circ}\)C), decreasing to 80% at 36 \({}^{\circ}\)C, before returning to 95% at 70 \({}^{\circ}\)C [37]. Also, the EAL overestimation was seen in the presence of 0.1% OCT and 2% CHX, and underestimation was seen in the presence of 5% heated and nonheated sodium hypochlorite [22]. The presence of the 2.5% sodium hypochlorite (NaOCl), 0.9% saline solution (NaCl), and 17% EDTA affected the accuracy of the Dentaport ZX and Rootor EAL, and most accurate measurements were obtained in dry canals [23]. In one study, with two apex locators, saline and EDTA gave precise results close to the actual length. Thus, these irrigants can be considered as reliable solutions for electronic measurements. Large deviation occurred with the more conductive solutions such as NaOCl and Chlorexidine digluconate [28]. A meta-analysis from fifteen studies regarding the accuracy of different generations of apex locators in determining working length showed that there was no significant difference among the generations of EALs in the determination of working length [9]. Also, another study compared the accuracy of the working length of two generations of EALs (3 rd vs. 4 th). Statistically, both third-generation and fourth-generation apex locators are equally accurate in the determination of working length [38]. However, the type of irrigant appears to affect the accuracy of the EAL with respect to its generation, so it is very important to know the specific irrigating medium used with each specific EAL to achieve the most accurate ACL results during root canal treatment [39]. When using tolerance \(\pm\)0.5 mm, the Raypex and Ipex showed an accuracy of 64.29% under 2.5% NaOCl, which is lower than the results in our study [40]. [PERSON] et al. reported an accuracy of 90.9% for the Raypex 6 EAL using tolerance \(\pm\)0.5 mm and 0.9% NaCl irrigant [41]. Ipex II, also a fourth-generation EAL like Ipex, showed an accuracy of 90% with a tolerance of \(\pm\)0.5 mm with a 5.25% NaOCl canal irrigation agent [42]. Even with artificially created canal perforations and various canal irrigation agents, Ipex and other EALs showed clinically acceptable results, although they were better in dry canals [43]. Based on our work and that of numerous other researches, we can conclude that are some differences in the accuracy of different EALs with regard to their generation. Therefore, we can conclude that the fourth and fifth-generation EALs used in this study have similar results and are quite accurate. The measured canal length was adversely affected by different canal irrigant solutions. The Raypex EAL showed an accuracy of 87.5% for the 0.9% saline solution and 82.5% for Chlorcid (3% NaOCl), and the Ipex EAL showed an accuracy of 82.5% with the 0.9% saline solution and 80% for Chlorcid (3% NaOCl). The greatest variations in accuracy were for the combinations of Raypex and EDTA 18% and for the Ipex and Glyde EDTA 17% (\(p=0.026\)).