Vol 2, No 1 (2014) ISSN 2167-8677 (online) DOI 10.5195/d3000.2014.26 http://dentistry3000.pitt.edu New electronic apex locator Romiapex A-15 presented accuracy for working length determination in permanent teeth Etevaldo Matos Maia Filho1, Cláudia de Castro Rizzi2, Daniela Silva Barroso de Oliveira3, Paulo Nelson Filho4, Raquel Assed Bezerra da Silva4, Léa Assed Bezerra da Silva4 1School of Dentistry of Ceuma University, São Luís, Maranhão, Brazil. 2PhD Student, Department of Pediatric Clinics, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil; School of Dentistry of Ceuma University, São Luís, Maranhão, Brazil. 3PhD Student, Department of Pediatric Clinics, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil; School of Dentistry, Federal University of Alfenas, Alfenas, Minas Gerais, Brazil. 4Department of Pediatric Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil. Abstract Purpose: The present study aims to evaluate, ex vivo, the accuracy of electronic apex locators Root ZX II and Romiapex-15, for working length (WL) determination in permanent teeth. Ma- terials and Methods: Fourteen single-rooted teeth (incisors and canines), with their apices fully formed were used. The dental crowns were removed. The anatomic length of the tooth (real measurement) was visually determined through the insertion of a size 10 K-file until the tip of the instrument could be observed in the apical foramen under a microscope (20X). Teeth were fixed in a model of resin and adapted into alginate soaked with saline solution, which was used as an electrical conductor. Using a K-file, root canals were measured elec- tronically using both devices. The results obtained for each apex locator were compared to the real measurements. The accuracy between the devices was statistically analyzed using the Bland-Altman graph, Intraclass Correlation Coefficient (ICC), and Student’s t-test. Results: The mean difference between the measurements using the Root ZX II was 0.277mm greater than the real measurement, while the measurements from the Romiapex-15 were 0.308mm higher on average. The comparison between Root ZX II and Romiapex-15 had no significant difference (p= 0.868). Conclusion: It was concluded that Root ZX II and Romiapex-15 had sim- ilar accuracy. Romiapex-15 could be an option for WL determination in permanent teeth. Citation: Maia Filho EM, Rizzi CC, Oliveira DSB, Nelson-Filho P, Silva RAB, Silva LAB . (2014) New electronic apex locator Romiapex A-15 presented accuracy for working length determination in per- manent teeth. Dentistry 3000. 1:a001 doi:10.5195/d3000.2014.26 Received: September 22, 2014 Accepted: November 1, 2014 Published: December 18, 2014 Copyright: ©2014 Filho et al. This is an open ac- cess article licensed under a Creative Commons Attribution Work 4.0 United States License. Email: Raquel@forp.usp.br Introduction Working length (WL) determina- tion is a crucial step in endodontic treatment. However, the ideal WL for root canal treat- ment has been an issue of discussion and controversy. Sjogren et al., (1990) [1] per- formed an epidemiological study and ob- served that the endodontic treatment had a better prognosis when the apical limit obtu- ration was 2.0mm from the radiographic apex. These results were better explained by Ricucci and Langeland (1998) [2], who per- formed a microscopic study and found that the best condition of repair was when the in- strumentation and root canal filling re- mained close to the apical constriction. Thus, preferably, the instrumentation and the ob- turation should stay in the narrow portion of the root canal, i.e. in apical constriction, be- cause it causes less damage and thus pro- vides better conditions for repair [2]. The most popular method for the establishment of the WL is the radiographic method, which is based on the premise that http://dentistry3000.pitt.edu/ New electronic apex locator Romiapex A-15 presented accuracy for working length determination in permanent teeth Vol 2, No 1 (2014) DOI 10.5195/d3000.2014.26 http://dentistry3000.pitt.edu 2 the apical constriction is located between 0.5 to 1.0mm of the radiographic apex in both permanent and primary teeth [3,4]. Determi- nation using the radiographic method has several limitations, such as: distortion, shortening and lengthening of the image, variability of interpretation, and it can only represent dimensional structures in a two dimension image. In this way, the radio- graphic estimation may lead to over or under root canal instrumentation and/or obtura- tion. Currently, the method of WL deter- mination considered to be more accurate is electronic, which uses Electronic Apex Loca- tors (EAL) [5]. These devices are based on measurements of impedance ratio and are able to determine the distance between the highest foramen and the lowest foramen based on the difference in the file tip and the fluid in the channel at different frequencies through the electrical resistance of the den- tin [6]. Several models of EAL use the princi- ple of impedance to determine apical con- striction and published papers have showed their effectiveness in working length deter- mination [7-13]. Recently, electronic equipment has been popularized and the device Root ZX II (J. Morita, Tokyo, Japan) has been proven to be a reference for new equipment testing due to its good results [14-17]. However, new devices have been introduced to the market and it is mandatory to assess their ac- curacy to determine WL. Thus, considering that there are few studies evaluating the Ro- miapex A-15 [18-20], this ex vivo study aimed to evaluate the accuracy of Romiapex- 15 in the determination of the WL of perma- nent teeth in comparison to Root ZX II – a standard method used in literature. Materials and Methods This study was approved by the Re- search Ethics Committee of the University Center of Maranha o, Brazil (protocol num- ber 00519/11). Fourteen extracted hu- man teeth, both upper and lower, with a single root (incisors and canines) and with apices fully formed, were selected. The teeth were stored in 2.5% sodium hy- pochlorite solution for 6 hours and then stored in sterile saline solution. The crowns of the teeth were sectioned horizontally at the cementum-enamel junction in order to simplify access to the root canal and to obtain a relia- ble occlusal reference point. The canals were irrigated with saline solution and patency was checked with K-file size 10. If remnants of pulp were presented, they were removed. The real measurements of the root canal length were performed using a K-file with a silicone stopper passively introduced into the root canal until the tip was visible in the apical foramen. At this time, the silicone stopper was adjusted in occlusal reference and the file was removed from the root canal. The distance from the tip of the instrument to the stopper was recorded us- ing an electronic caliper with an approxima- tion of 0.01mm (Mitutoyo Digimatic, Kyoto, Japan). The measurements, in millimeters, were made by a calibrated examiner (Kappa = 0.9) and were recorded in specific charts. For WL determination with the electronic devices, the teeth were fixed in a model of resin and soaked up to 2mm below the cementum-enamel junction in alginate molding (Jeltrate II Dentply, Petropolis, Bra- zil). The alginate was prepared according to the manufacturer's recommendations. Root canals were filled with 1.0% sodium hypochlorite solution (Biodynamics, Sa o Paulo, Brazil). Cotton pellets were used elim- inate excess saline from the pulp chamber. The root canal of all teeth was measured using the electronic apex loca- tors Romiapex A-15 (Romidan Ltd, Kiryat Ono, Israel) and Root ZX II (J. Morita USA, Irvine, CA -USA). Ini- tially, a file was gen- tly inserted into the root canal until the appliance emitted a continuous audible tone and the word "APEX" flashed on the Root ZX II dis- play and “0.0” on the display of the Ro- miapex A-15. Then, the file was retracted until the display of both pieces of equipment indicated the position stabilized at 0.5. At this time, the silicone stopper was adjusted in occlusal reference, the file removed from the root canal, and the distance from the tip of the instrument to the stopper was recorded using a digital caliper. All of the measurements were car- ried out by a single calibrated examiner and the results (in millimeters) obtained from the two pieces of equipment were tabulated. The results were statistically ana- lyzed using the Bland-Altman graph and the Intraclass Correlation Coefficient (ICC) in or- der to test the null hypothesis that there is no correlation between the measurements and to compare the accuracy between the two Figure 1. Graphical representation of the difference in values ob- tained using the electronic apex locator Root ZX II and the real measurements. FiFifd Figure 2. Graphical representation of the difference in values ob- tained using the electronic apex locator Romiapex A-15 and the real measurements. http://dentistry3000.pitt.edu/ New electronic apex locator Romiapex A-15 presented accuracy for working length determination in permanent teeth Vol 2, No 1 (2014) DOI 10.5195/d3000.2014.26 http://dentistry3000.pitt.edu 3 devices and the real measurements. To as- sess whether there was a difference between both apex locators, Student's t-test was used. All analyses were carried out using the sta- tistical program SPSS version 19.00 (SPSS Inc., Chicago, IL, USA) with a significance level of 5%. Results Table 1 shows the differences be- tween both EAL and the real measurement, including the Intraclass Correlation Coeffi- cient (ICC) and p values. It was observed that the mean of the differences between the measurements using the Root ZX II was 0.277mm greater than the real measure- ments, while the Romiapex-15 measure- ments were 0.308mm higher on average. Figures 1 and 2 are a graphical rep- resentation of the differences between the measurement of linear distances obtained from both devices and real measurements. The vertical line represents the mean of the differences. The closer the vertical line is to zero, the greater the accuracy of the devices. The mean of the differences be- tween the measurements obtained with the Root ZX II and the Romiapex A-15 was 0.030. The Student's t-test showed that there was no statistically significant difference be- tween the measurements performed with Root ZX II and the Romiapex A-15 (p= 0.868). Discussion The evaluation of different endo- dontic equipment is important to guide clini- cians in their dental practice. Thus, in this study we evaluated two electronic apex loca- tors ex vivo in comparison to real measure- ments of root canals. In order to maintain the experimental condi- tions with the smallest number of possible variables, total removal of the dental crown was performed to design a more reliable ref- erence [21]. Canals were irrigated with 1.0% sodium hypochlorite and excess in the pulp chamber was removed by aspiration, while keeping the root canals wet, in order to use the devices according the manufacturers’ in- structions [22]. Also, according to the litera- ture, alginate was used for electrical conduc- tion in ex vivo studies with EAL [23]. In this study, the alginate was also used for mainte- nance of teeth and allowed electrical conduc- tion in the ex vivo evaluation. Several studies assessed the accu- racy of the EAL Root ZX II to determine the WL in deciduous and permanent teeth [14- 17; 24-26], and, due to the excellent results found, this device has been used as parame- ter for comparison with other equipment. Although other previous studies attempted to evaluate Romiapex A-15 [18-20], our study adds important information to endo- dontic literature confirming the accuracy of both tested apex locators. It is recommended to use the tech- nique of apical setback to establish the WL using EAL. This consist of the introduction of the file to the foramen (which appears on the devices’ screen as “0.0” or “APEX”), and then performing the setback until the apical con- striction is reached. This technique allows the user to identify the first contrition to- ward the apex-crown. According Ricucci (1998) [27], this constriction is located 0.5 to 1.0mm coronal to the foramen and is consid- ered an ideal spot for instrumentation and obturation of the root canals. The average difference between the measurements obtained with the Ro- miapex A-15 and the real measurements (0.308mm) was greater than the mean dif- ference obtained with the Root ZX II and the real measurements (0.277mm). The varia- tion of ± 0.5mm in WL is acceptable to avoid over-instrumentation [28]. Therefore, we can conclude that both devices were within the recommended standards. Romiapex A-15 presented a lower dispersion (standard deviation = 0.391mm) compared to the Root ZX II (standard devia- tion = 0.472). In addition, the error ranging was 0.542 for the Romiapex A-15, while it was 0.654 for the Root ZX II. This means that the measurements obtained with the Ro- miapex A-15 showed a lower oscillation pat- tern. Measurements obtained with the Ro- miapex A-15 were closer to the vertical line than the measurements from the Root ZX II. The smallest variation of measurements ob- tained with Romiapex A-15 represents the high correlation with the real measurement showed by the interclass test. However, when the difference in measurements ob- tained with both devices was assessed, no statistical difference was found. It is im- portant to emphasize that the difference found in this study is not clinically significant for endodontic treatment, which corrobo- rates with Vasconcelos et al. (2013) [28]. Conclusion Although ex vivo studies have some limita- tions, it is possible to conclude that the elec- tronic apex locator Romiapex-15 presented accuracy in the determination of the WL in single-rooted permanent teeth and had re- sults similar to the Root ZX II. References 1. 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