- Email: [email protected]
Influence of pulp vitality on length determination by using the elements diagnostic unit and apex locator
Influence of pulp vitality on length determination by using the elements diagnostic unit and apex locator Eduardo Akisue, DDS, MSc,a Giulio Gavini, DDS, MSc, PhD,b,c and Jose Antonio Poli de Figueiredo, DDS, MSc, PhD,d Santos, Sao Paulo, Brazil, Sao Paulo, Sao Paulo, Brazil, and London, England SANTA CECILIA UNIVERSITY, UNIVERSITY OF SAO PAULO, AND UNIVERSITY COLLEGE LONDON
Objective. The aim of this study was to compare the influence of the pulp condition (vital or necrotic) on the determination of the root canal length by using a fourth generation electronic apex locator (EAL). Study design. The Elements Diagnostic Unit and Apex Locator was used to measure 143 teeth, totaling 294 canals with different conditions (236 necrotic and 58 vital pulp), for root length. After assessing the root canal and ascertaining the tooth length by using the EAL, the position of the file was confirmed by radiograph. The distance between the file tip and the root end was measured radiographically and was compared with the electronic measurement. Results. Under clinical conditions within an acceptable range lower than 0.5 mm, the concordance between the 2 measurements was 96.6%. This new EAL showed no significant difference (P ⱕ .05) on accuracy of root canal length determination between vital cases (94.8%) and necrotic cases (97%). Conclusion. This device proved to be reliable regardless of the pulpal vitality. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;104:e129-e132)
Establishing the root canal length is an important step for the success of endodontic therapy. The widely accepted working length during the instrumentation is the occlusal or incisal distance between 1 reference point occlusally or incisally on the tooth and the cementodentinal junction or apical constriction.1-3 Although dentists routinely use radiography to determine the working length, it is subject to distortions, and the apical foramen usually is not seen in radiographs. In cases where the apical foramen is eccentric to the root apex, radiographic methods are often inaccurate and result in overextension of root canal instrumentation.1 Several studies have shown that the mean distance from the apex to apical constriction is around 0.5 mm to 1.0 mm.4,5 Electronic apex locators (EALs) have been developed to determine the working length during endodontic treatment. The principle of the electrical location was first studied by Suzuki6 where he demonstrated that the electrical resistance between the periodontal ligaa
Clinical Lecturer, Endodontic Department, Santa Cecilia University. Chairman, Endodontic Department, Santa Cecilia University. c Reader, Endodontic Department, University of Sao Paulo. d Clinical Lecturer, Unit of Endodontology, UCL Eastman Dental Institute, University College London. Received for publication Aug 11, 2006; returned for revision Apr 12, 2007; accepted for publication Apr 17, 2007. 1079-2104/$ - see front matter © 2007 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2007.04.018 b
ment and the oral mucous membranes is constant and equal to 6.5 ohms. This led to development of the first EAL by Sunada7 and brings this unit into the clinical practice, where it works by analyzing the decrease in impedance when the instrument reaches the apical constriction or apical foramen. The first generation of apex locators used the principle of DC resistance, and the second generation, AC single-frequency impedance. A few years ago, the third generation was introduced and it was based on the ratio of dual-channel or multichannel impedance principle. Different than the other apex locators, the new apex locator studied here, the Elements Diagnostic Unit and Apex Locator (SybronEndo, Orange, CA), is classified as the fourth generation and works by breaking the impedance down into its primary components (resistance and capacitance) and measuring them directly and independently during use. This reading theoretically results in a more precise measurement. This device allows root canal length determination in a canal filled with different electrolytes, such as sodium hypochlorite, blood, and exudates. A literature search revealed few ex vivo8 and in vivo9 studies evaluating the influence of the pulp condition on the length determination by using this fourth generation EAL. The objective of this study was to evaluate in vivo the root canal length measurement by the Elements Diagnostic Unit and Apex Locator in vital and necrotic pulp conditions. e129
e130
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Table I. Measurement results
Table II. Statistical analysis
Measurement No. of necrotic No. of vital difference Frequency Percent canals* (%) canals† (%) 0.0 mm 0.1 mm 0.2 mm 0.3 mm 0.4 mm ⱖ0.5 mm
85 94 83 19 3 10
28.912 31.973 28.231 6.463 1.020 3.401
70 (29.661) 78 (33.051) 65 (27.542) 14 (5.932) 2 (0.848) 7 (2.966)
15 (25.862) 16 (27.586) 18 (31.035) 5 (8.620) 1 (1.724) 3 (5.173)
*n ⫽ 236. †n ⫽ 58.
MATERIAL AND METHODS Ninety-nine patients from the Santa Cecilia University endodontic clinic, with indication for root canal treatment (143 teeth and 294 roots with mature apices), were used in this study. Each patient was informed of the steps involving the electrical root measurement, and an informed written consent, approved by the Santa Cecilia University Ethics Committee, was obtained from each patient. All clinical procedures and measurements were conducted by the principal investigator. The teeth were checked for sensitivity by using the Endo Ice coolant spray (Hygenic Corp., Akron, OH), and results were recorded as vital or necrotic after pulp access and confirmation of vascular status. Twentyeight teeth (58 canals) were diagnosed as vital and 115 teeth (236 canals) as necrotic. Each patient was anaesthetized, a rubber dam was positioned, the endodontic access was prepared, and the coronal/medium third of each canal was flared with K3 files size 25 (.10 taper) and size 25 (.08 taper). The canals were cleansed of debris by irrigating with 1% sodium hypochlorite solution, and the excess fluid was aspirated from the root canal. The working length determination was performed using the Elements Diagnostic Unit and Apex Locator. The EAL probe and lip clip were placed and the K-file, according to the size of each canal, was advanced apically. When the apex locator indicated readings between 0.5 mm and 1.0 mm, the position of the file was confirmed by radiograph. Each radiograph was analyzed by 3 endodontists using a 4⫻ magnifying lens to verify radiographic distortions and to determine the distance between the file tip and the end of the root. Radiographic images with distortions were retaken until an ideal image was achieved. More than 1 radiograph of multirooted teeth was taken when needed to show clearly each canal to be measured. The radiographic measurement was standardized and recorded as 0.5 mm, 1 mm, and 1.5 mm from the apex, or exactly at the apex. All measurements with the apex locator
Measurement difference 0.0 mm 0.1 mm 0.2 mm 0.3 mm 0.4 mm ⱖ0.5 mm
No. of No. of necrotic vital P canals* Percent canals† Percent Test value 70 78 65 14 2 7
29.7 33.1 27.5 5.9 0.8 3.0
15 16 18 5 1 3
25.9 27.6 31.0 8.6 1.7 5.2
2 2 2 FET FET FET
.567 .424 .597 .549 .484 .420
FET, Fisher exact test. *n ⫽ 236. †n ⫽ 58.
were verified 3 times before being recorded. To determine the accuracy, the distances measured by the apex locator and those calculated from the radiographic analysis were compared. Data was subjected to statistical analysis, with significance set at a level of .05. Statistical analysis Pearson’s chi-square test was applied to assess the relationship between qualitative or categorical variables (pulp condition) by using SAS version 8.2 (SAS Institute, Cary, NC).2 Statistically, when 20% or more of the cells had expected counts of less than 5, the Fisher exact test was used. All tests were 2-tailed, and an ␣ level of .05 was considered significant. RESULTS The differences between the 2 measurement methods (electronic and X-ray analysis) are shown in Table I. If the difference between the apex locator indication and the measurement in the radiography was in the range of 0.0 mm to 0.4 mm, it was classified as an acceptable result totaling 96.599%; if the distance was equal to or greater than 0.5 mm, this result was considered unacceptable. As shown in Table II, the Pearson’s chi-square statistic test and the Fisher exact test revealed no significant difference between pulp conditions for all measurement differences. DISCUSSION Many studies verified the precision of the thirdgeneration apex locator, demonstrating a high success when using an in vivo radiographic method10 or an in vivo extracted tooth–length method.11-16 De Moor et al.17 compared 4 apical locators in vitro by subtracting the true canal lengths of each tooth from the measurements taken with the EALs, where positive measurements indicated long measurements (i.e., beyond the apical foramen) and negative measurements
OOOOE Volume 104, Number 4
indicated short measurements. All measurements falling in the range of ⫾0.5 mm from the apical foramen were determined to be acceptable. From the results, the authors demonstrated a good performance of the thirdgeneration AFA 7005 apex locator (Analytic Endodontics, Orange, CA) under these conditions, and based on a precision of ⫾0.1 mm from the apical foramen, showed the AFA 7005 to be the most accurate. Akisue et al.3 showed the high in vivo accuracy (94.6%) of the apex locator AFA 7005 under an acceptable range of ⫾0.3 mm when compared with the radiographic distance between the file tip and apex with the data obtained using the EAL. Using similar methodology, Pommer et al.2 showed this unit effective for 93.9% of cases with vital pulp tissue, asserting that this apex locator could be used to determine the working length with great confidence. Recently, in a ex vivo study, Plotino et al.8 showed that RootZX (J. Morita, Irvine, CA), Elements Diagnostic Unit and Apex Locator, and ProPex (Dentsply, Maillefer, Ballaigues, Switzerland) can accurately determine the root canal length within the same range of ⫾0.5 mm when the reference length (real length) is subtracted from the electronically determined distance. Comparing the differences between the data obtained, the percentage of agreement under this range was 94.3% for the Elements Diagnostic Unit and Apex Locator, 97.4% for RootZX, and 100% for ProPex. The minor mean difference of ⫺0.1 ⫾ 0.3 mm was shown by the Elements Unit. Tselnik et al.9 compared in vivo the accuracy of the Root ZX and Elements Diagnostic Unit and Apex Locator under clinical conditions. Teeth planned for extraction were used for working length measurement, and after extraction, the apical 4 mm of each canal were exposed and the distance from the file tip to the minor diameter was determined. In locating the minor constriction, both units showed to be accurate 75% of the time to a ⫾0.5-mm range, without a statistically significant difference. In this study, using the same fourth-generation apex locator, the mean differences between the electronic measurements and the radiographic analysis shown in Table I demonstrated that identical measurements occurred in 28.9% and in 31.9% for 0.1 mm of difference. These 2 measurements conduct to the general mean difference of ⫺0.13 ⫾ 0.12 mm that is similar to findings from Plotino et al.8 In the same manner, it was also shown that under clinical conditions within an acceptable range of 0.5 mm difference, the agreement of measurements was 96.6%. This range value (0.5 mm) was chosen based on previous in vivo studies that used the same range method.2,8,9,12-14 However, the radiographic limitations should also be considered, and distortions can occur
Akisue et al. e131
sometimes. It could be speculated that if such a high rate was achieved using the radiographic method, doing it in an ex vivo model could bring even higher results. This high percentage of accuracy is related with the capacity of this EAL to break the impedance into its primary components (resistance and capacitance) and measuring those directly and independently during use. This would eliminate any erroneous readings due to different combinations of these properties, which provide the same impedance reading. In others words, a combination of “A” resistance and “B” capacitance gives a reading of “X” impedance, but the combination of “R” resistance and “S” resistance also gives the same “X” impedance. In this case, you have 2 different situations that would give the same feedback (and thus the same reading of location within the canal), even though they are not equivalent. According to the manufacturer, some apex locators can sometimes appear jumpy and erratic, so the Elements Diagnostic Unit and Apex Locator would eliminate the chance of that happening, making the unit feel more stable, resulting in faster measurements with more precision. The influence of the operator’s accuracy of a specific device has not yet been demonstrated in the literature, but some practice is required to become familiar with these devices before accurate measurements can be obtained routinely. Part of the results with more than 0.3 mm of difference between the electronic measurements and radiographic analysis occurred in the beginning of this study when the operator was not familiarized with this unit. All measurements were conducted by the principal investigator (E.A.), who has had 2 years of experience with this unit. Mayeda et al.18 and Dunlap et al.10 demonstrated that there was no statistical difference in measurement between vital and nonvital groups. Arora and Gulabivala19 showed that the EAL gave more accurate measurements in vital canals (94.4%) than in necrotic canals (81.8%). The same conclusions were shown by Pommer et al.,2 where the Elements Diagnostic Unit and Apex Locator AFA 7005 detects the apical constriction in 76.6% of necrotic canals and in 93.9% of vital canals. In our study, this new apex locator showed no difference in accuracy of root canal length determination between vital canals (94.8%) and necrotic canals (97%), revealing no significant difference (P ⱕ .05). These results were also comparable with findings of the examination of Mayeda et al.18 and Dunlap et al.10 The accuracy is influenced by 2 factors: moisture content of the root canal and diameter of the apical constriction.4,20 The same occurs in immature and “blunderbuss” apices.16,21 The present study showed few measurement failures that could be supposed by the large diameter of the apical foramen.
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The values observed with the apex locator display showed a high agreement rate when compared with the values measured by radiographic analysis. Therefore, it could be concluded that the Elements Diagnostic Unit and Apex Locator is accurate when used to determine working length in endodontic therapy in vital and necrotic teeth, without significant difference between these 2 conditions. REFERENCES 1. Palmer MJ, Weine FS, Healey HJ. Position of the apical foramen in relation to endodontic therapy. J Can Dent Assoc (Tor) 1971;37:305-8. 2. Pommer O, Stamm O, Attin T. Influence of the canal contents on the electrical assisted determination of the length of root canals. J Endod 2002;28:83-5. 3. Akisue E, Gavini G, Aun CE. Apex location using the impedance principle of resistance. Endod Practice 2000;4:22-6. 4. Huang L. An experimental study of the principle of electronic root canal measurement. J Endod 1987;13:60-4. 5. Green D. Stereomicroscopic study of 700 root apices of maxillary and mandibular posterior teeth. Oral Surg Oral Med Oral Pathol 1960;13:728-33. 6. Suzuki K. Experimental study on iontophoresis. J Jap Stomatol 1942;16:411-7. 7. Sunada I. New method for measuring the length of the root canal. J Dent Res 1962;41:375-87. 8. Plotino G, Grande NM, Brigante L, Lesti B, Somma F. Ex vivo accuracy of three electronic apex locators: Root ZX, Elements Diagnostic Unit and Apex locator and ProPex. Int Endod J 2006;39:408-14. 9. Tselnik M, Baumgartner JC, Marshall JG. An evaluation of root ZX and Elements apex locators. J Endod 2005;31:507-9. 10. Dunlap CA, Remeikis NA, BeGole EA, Rauschenberger CR. An in vivo evaluation of an electronic apex locator that uses the ratio method in vital and necrotic canals. J Endod 1998;24:48-50.
11. Shabahang S, Goon WWY, Gluskin AII. An in vivo evaluation of Root ZX electronic apex locator. J Endod 1996;22:616-8. 12. Vajrabhaya L, Tepmongkol P. Accuracy of apex locator. Endod Dent Traumatol 1997;13:180-2. 13. Pagavino G, Pace R, Baccetti T. A SEM study of in vivo accuracy of the Root ZX electronic apex locator. J Endod 1998;24:438-41. 14. McDonald NJ, Pileggi R, Glickman G, Varella C. An in vivo evaluation of third generation apex locators [abstract]. J Dent Res 1999;78:373. 15. Weiger R, John C, Geigle H, Lost C. An in vitro comparison of two modern apex locators. J Endod 1999;25:765-8. 16. Welk AR, Baumgartner JC, Marshall JG. An in vivo comparison of two frequency-based electronic apex locators. J Endod 2003; 29:497-500. 17. De Moor RJG, Hommez GMG, Martens LC, De Boever JG. Accuracy of four electronic apex locators: an in vitro evaluation. Endod Dent Traumatol 1999;15:77-82. 18. Mayeda DL, Simon JHS, Aimar DF, Finley K. In vivo measurement accuracy in vital and necrotic canals with the Endex apex locator. J Endod 1993;19:545-8. 19. Arora RK, Gulabivala K. An in vitro evaluation of the Endex and RCM Mark II electronic apex locators in root canals with different contents. Oral Surg Oral Med Oral Pathol 1995;79: 497-503. 20. Stein TJ, Corcoran JF, Zillich RM. Influence of the major and minor foramen diameters on apical electronic probe measurements. J Endod 1990;16:520-2. 21. Berman LH, Fleischman SB. Evaluation of the accuracy of the Neosono-D electronic apex locator. J Endod 1984;10:164-7. Reprint requests: Jose Antonio Poli de Figueiredo, DDS, MSc, PhD Clinical Lecturer in Endodontology Unit of Endodontology UCL-Eastman Dental Institute 256 Gray’s Inn Road London, WC1X 8LD United Kingdom
Objective. The aim of this study was to compare the influence of the pulp condition (vital or necrotic) on the determination of the root canal length by using a fourth generation electronic apex locator (EAL). Study design. The Elements Diagnostic Unit and Apex Locator was used to measure 143 teeth, totaling 294 canals with different conditions (236 necrotic and 58 vital pulp), for root length. After assessing the root canal and ascertaining the tooth length by using the EAL, the position of the file was confirmed by radiograph. The distance between the file tip and the root end was measured radiographically and was compared with the electronic measurement. Results. Under clinical conditions within an acceptable range lower than 0.5 mm, the concordance between the 2 measurements was 96.6%. This new EAL showed no significant difference (P ⱕ .05) on accuracy of root canal length determination between vital cases (94.8%) and necrotic cases (97%). Conclusion. This device proved to be reliable regardless of the pulpal vitality. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;104:e129-e132)
Establishing the root canal length is an important step for the success of endodontic therapy. The widely accepted working length during the instrumentation is the occlusal or incisal distance between 1 reference point occlusally or incisally on the tooth and the cementodentinal junction or apical constriction.1-3 Although dentists routinely use radiography to determine the working length, it is subject to distortions, and the apical foramen usually is not seen in radiographs. In cases where the apical foramen is eccentric to the root apex, radiographic methods are often inaccurate and result in overextension of root canal instrumentation.1 Several studies have shown that the mean distance from the apex to apical constriction is around 0.5 mm to 1.0 mm.4,5 Electronic apex locators (EALs) have been developed to determine the working length during endodontic treatment. The principle of the electrical location was first studied by Suzuki6 where he demonstrated that the electrical resistance between the periodontal ligaa
Clinical Lecturer, Endodontic Department, Santa Cecilia University. Chairman, Endodontic Department, Santa Cecilia University. c Reader, Endodontic Department, University of Sao Paulo. d Clinical Lecturer, Unit of Endodontology, UCL Eastman Dental Institute, University College London. Received for publication Aug 11, 2006; returned for revision Apr 12, 2007; accepted for publication Apr 17, 2007. 1079-2104/$ - see front matter © 2007 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2007.04.018 b
ment and the oral mucous membranes is constant and equal to 6.5 ohms. This led to development of the first EAL by Sunada7 and brings this unit into the clinical practice, where it works by analyzing the decrease in impedance when the instrument reaches the apical constriction or apical foramen. The first generation of apex locators used the principle of DC resistance, and the second generation, AC single-frequency impedance. A few years ago, the third generation was introduced and it was based on the ratio of dual-channel or multichannel impedance principle. Different than the other apex locators, the new apex locator studied here, the Elements Diagnostic Unit and Apex Locator (SybronEndo, Orange, CA), is classified as the fourth generation and works by breaking the impedance down into its primary components (resistance and capacitance) and measuring them directly and independently during use. This reading theoretically results in a more precise measurement. This device allows root canal length determination in a canal filled with different electrolytes, such as sodium hypochlorite, blood, and exudates. A literature search revealed few ex vivo8 and in vivo9 studies evaluating the influence of the pulp condition on the length determination by using this fourth generation EAL. The objective of this study was to evaluate in vivo the root canal length measurement by the Elements Diagnostic Unit and Apex Locator in vital and necrotic pulp conditions. e129
e130
OOOOE October 2007
Akisue et al.
Table I. Measurement results
Table II. Statistical analysis
Measurement No. of necrotic No. of vital difference Frequency Percent canals* (%) canals† (%) 0.0 mm 0.1 mm 0.2 mm 0.3 mm 0.4 mm ⱖ0.5 mm
85 94 83 19 3 10
28.912 31.973 28.231 6.463 1.020 3.401
70 (29.661) 78 (33.051) 65 (27.542) 14 (5.932) 2 (0.848) 7 (2.966)
15 (25.862) 16 (27.586) 18 (31.035) 5 (8.620) 1 (1.724) 3 (5.173)
*n ⫽ 236. †n ⫽ 58.
MATERIAL AND METHODS Ninety-nine patients from the Santa Cecilia University endodontic clinic, with indication for root canal treatment (143 teeth and 294 roots with mature apices), were used in this study. Each patient was informed of the steps involving the electrical root measurement, and an informed written consent, approved by the Santa Cecilia University Ethics Committee, was obtained from each patient. All clinical procedures and measurements were conducted by the principal investigator. The teeth were checked for sensitivity by using the Endo Ice coolant spray (Hygenic Corp., Akron, OH), and results were recorded as vital or necrotic after pulp access and confirmation of vascular status. Twentyeight teeth (58 canals) were diagnosed as vital and 115 teeth (236 canals) as necrotic. Each patient was anaesthetized, a rubber dam was positioned, the endodontic access was prepared, and the coronal/medium third of each canal was flared with K3 files size 25 (.10 taper) and size 25 (.08 taper). The canals were cleansed of debris by irrigating with 1% sodium hypochlorite solution, and the excess fluid was aspirated from the root canal. The working length determination was performed using the Elements Diagnostic Unit and Apex Locator. The EAL probe and lip clip were placed and the K-file, according to the size of each canal, was advanced apically. When the apex locator indicated readings between 0.5 mm and 1.0 mm, the position of the file was confirmed by radiograph. Each radiograph was analyzed by 3 endodontists using a 4⫻ magnifying lens to verify radiographic distortions and to determine the distance between the file tip and the end of the root. Radiographic images with distortions were retaken until an ideal image was achieved. More than 1 radiograph of multirooted teeth was taken when needed to show clearly each canal to be measured. The radiographic measurement was standardized and recorded as 0.5 mm, 1 mm, and 1.5 mm from the apex, or exactly at the apex. All measurements with the apex locator
Measurement difference 0.0 mm 0.1 mm 0.2 mm 0.3 mm 0.4 mm ⱖ0.5 mm
No. of No. of necrotic vital P canals* Percent canals† Percent Test value 70 78 65 14 2 7
29.7 33.1 27.5 5.9 0.8 3.0
15 16 18 5 1 3
25.9 27.6 31.0 8.6 1.7 5.2
2 2 2 FET FET FET
.567 .424 .597 .549 .484 .420
FET, Fisher exact test. *n ⫽ 236. †n ⫽ 58.
were verified 3 times before being recorded. To determine the accuracy, the distances measured by the apex locator and those calculated from the radiographic analysis were compared. Data was subjected to statistical analysis, with significance set at a level of .05. Statistical analysis Pearson’s chi-square test was applied to assess the relationship between qualitative or categorical variables (pulp condition) by using SAS version 8.2 (SAS Institute, Cary, NC).2 Statistically, when 20% or more of the cells had expected counts of less than 5, the Fisher exact test was used. All tests were 2-tailed, and an ␣ level of .05 was considered significant. RESULTS The differences between the 2 measurement methods (electronic and X-ray analysis) are shown in Table I. If the difference between the apex locator indication and the measurement in the radiography was in the range of 0.0 mm to 0.4 mm, it was classified as an acceptable result totaling 96.599%; if the distance was equal to or greater than 0.5 mm, this result was considered unacceptable. As shown in Table II, the Pearson’s chi-square statistic test and the Fisher exact test revealed no significant difference between pulp conditions for all measurement differences. DISCUSSION Many studies verified the precision of the thirdgeneration apex locator, demonstrating a high success when using an in vivo radiographic method10 or an in vivo extracted tooth–length method.11-16 De Moor et al.17 compared 4 apical locators in vitro by subtracting the true canal lengths of each tooth from the measurements taken with the EALs, where positive measurements indicated long measurements (i.e., beyond the apical foramen) and negative measurements
OOOOE Volume 104, Number 4
indicated short measurements. All measurements falling in the range of ⫾0.5 mm from the apical foramen were determined to be acceptable. From the results, the authors demonstrated a good performance of the thirdgeneration AFA 7005 apex locator (Analytic Endodontics, Orange, CA) under these conditions, and based on a precision of ⫾0.1 mm from the apical foramen, showed the AFA 7005 to be the most accurate. Akisue et al.3 showed the high in vivo accuracy (94.6%) of the apex locator AFA 7005 under an acceptable range of ⫾0.3 mm when compared with the radiographic distance between the file tip and apex with the data obtained using the EAL. Using similar methodology, Pommer et al.2 showed this unit effective for 93.9% of cases with vital pulp tissue, asserting that this apex locator could be used to determine the working length with great confidence. Recently, in a ex vivo study, Plotino et al.8 showed that RootZX (J. Morita, Irvine, CA), Elements Diagnostic Unit and Apex Locator, and ProPex (Dentsply, Maillefer, Ballaigues, Switzerland) can accurately determine the root canal length within the same range of ⫾0.5 mm when the reference length (real length) is subtracted from the electronically determined distance. Comparing the differences between the data obtained, the percentage of agreement under this range was 94.3% for the Elements Diagnostic Unit and Apex Locator, 97.4% for RootZX, and 100% for ProPex. The minor mean difference of ⫺0.1 ⫾ 0.3 mm was shown by the Elements Unit. Tselnik et al.9 compared in vivo the accuracy of the Root ZX and Elements Diagnostic Unit and Apex Locator under clinical conditions. Teeth planned for extraction were used for working length measurement, and after extraction, the apical 4 mm of each canal were exposed and the distance from the file tip to the minor diameter was determined. In locating the minor constriction, both units showed to be accurate 75% of the time to a ⫾0.5-mm range, without a statistically significant difference. In this study, using the same fourth-generation apex locator, the mean differences between the electronic measurements and the radiographic analysis shown in Table I demonstrated that identical measurements occurred in 28.9% and in 31.9% for 0.1 mm of difference. These 2 measurements conduct to the general mean difference of ⫺0.13 ⫾ 0.12 mm that is similar to findings from Plotino et al.8 In the same manner, it was also shown that under clinical conditions within an acceptable range of 0.5 mm difference, the agreement of measurements was 96.6%. This range value (0.5 mm) was chosen based on previous in vivo studies that used the same range method.2,8,9,12-14 However, the radiographic limitations should also be considered, and distortions can occur
Akisue et al. e131
sometimes. It could be speculated that if such a high rate was achieved using the radiographic method, doing it in an ex vivo model could bring even higher results. This high percentage of accuracy is related with the capacity of this EAL to break the impedance into its primary components (resistance and capacitance) and measuring those directly and independently during use. This would eliminate any erroneous readings due to different combinations of these properties, which provide the same impedance reading. In others words, a combination of “A” resistance and “B” capacitance gives a reading of “X” impedance, but the combination of “R” resistance and “S” resistance also gives the same “X” impedance. In this case, you have 2 different situations that would give the same feedback (and thus the same reading of location within the canal), even though they are not equivalent. According to the manufacturer, some apex locators can sometimes appear jumpy and erratic, so the Elements Diagnostic Unit and Apex Locator would eliminate the chance of that happening, making the unit feel more stable, resulting in faster measurements with more precision. The influence of the operator’s accuracy of a specific device has not yet been demonstrated in the literature, but some practice is required to become familiar with these devices before accurate measurements can be obtained routinely. Part of the results with more than 0.3 mm of difference between the electronic measurements and radiographic analysis occurred in the beginning of this study when the operator was not familiarized with this unit. All measurements were conducted by the principal investigator (E.A.), who has had 2 years of experience with this unit. Mayeda et al.18 and Dunlap et al.10 demonstrated that there was no statistical difference in measurement between vital and nonvital groups. Arora and Gulabivala19 showed that the EAL gave more accurate measurements in vital canals (94.4%) than in necrotic canals (81.8%). The same conclusions were shown by Pommer et al.,2 where the Elements Diagnostic Unit and Apex Locator AFA 7005 detects the apical constriction in 76.6% of necrotic canals and in 93.9% of vital canals. In our study, this new apex locator showed no difference in accuracy of root canal length determination between vital canals (94.8%) and necrotic canals (97%), revealing no significant difference (P ⱕ .05). These results were also comparable with findings of the examination of Mayeda et al.18 and Dunlap et al.10 The accuracy is influenced by 2 factors: moisture content of the root canal and diameter of the apical constriction.4,20 The same occurs in immature and “blunderbuss” apices.16,21 The present study showed few measurement failures that could be supposed by the large diameter of the apical foramen.
e132
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Akisue et al.
The values observed with the apex locator display showed a high agreement rate when compared with the values measured by radiographic analysis. Therefore, it could be concluded that the Elements Diagnostic Unit and Apex Locator is accurate when used to determine working length in endodontic therapy in vital and necrotic teeth, without significant difference between these 2 conditions. REFERENCES 1. Palmer MJ, Weine FS, Healey HJ. Position of the apical foramen in relation to endodontic therapy. J Can Dent Assoc (Tor) 1971;37:305-8. 2. Pommer O, Stamm O, Attin T. Influence of the canal contents on the electrical assisted determination of the length of root canals. J Endod 2002;28:83-5. 3. Akisue E, Gavini G, Aun CE. Apex location using the impedance principle of resistance. Endod Practice 2000;4:22-6. 4. Huang L. An experimental study of the principle of electronic root canal measurement. J Endod 1987;13:60-4. 5. Green D. Stereomicroscopic study of 700 root apices of maxillary and mandibular posterior teeth. Oral Surg Oral Med Oral Pathol 1960;13:728-33. 6. Suzuki K. Experimental study on iontophoresis. J Jap Stomatol 1942;16:411-7. 7. Sunada I. New method for measuring the length of the root canal. J Dent Res 1962;41:375-87. 8. Plotino G, Grande NM, Brigante L, Lesti B, Somma F. Ex vivo accuracy of three electronic apex locators: Root ZX, Elements Diagnostic Unit and Apex locator and ProPex. Int Endod J 2006;39:408-14. 9. Tselnik M, Baumgartner JC, Marshall JG. An evaluation of root ZX and Elements apex locators. J Endod 2005;31:507-9. 10. Dunlap CA, Remeikis NA, BeGole EA, Rauschenberger CR. An in vivo evaluation of an electronic apex locator that uses the ratio method in vital and necrotic canals. J Endod 1998;24:48-50.
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