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Influence of Blood on the Accuracy of Raypex 5 and Root ZX Electronic Foramen Locators: An In Vivo Study

Abstract

The aim of this study was to evaluate in vivo the accuracy of the Raypex 5 and Root ZX electronic foramen locators (EFLs) in the presence of blood in the root canal space. Forty single-canal teeth scheduled for extraction were selected. Access cavity was prepared and coronal enlargement was carried out. Approximately two drops of blood were collected by finger prick and injected into the root canal space. The electronic working length (EWL) of each tooth by each device was established twice before (NB group) and after (WB group) injecting blood into the root canal. The tooth was extracted and the actual working length (AWL) was determined. Data were analyzed using McNemar's test. The accuracy rates of Raypex 5 and Root ZX within 0.5 mm in the NB group were 88.9% and 91.5%, with 83.3% and 86.2% in the WB group, respectively. There were no significant differences between the accuracy of each EFL in the two groups (p>0.05). Considering the NB and WB groups, there were no statistically significant differences in the accuracy of the EFLs (p>0.05). The presence of blood in the root canal space did not influence the accuracy of the EFLs.

Key Words:
blood; electronic apex locators; endodontics; working length.

Resumo

Este estudo objetivou avaliar in vivo a precisão dos localizadores foraminais eletrônicos (EFLs) Raypex 5 e Root ZX em presença de sangue no canal radicular. Foram utilizados 40 dentes unirradiculares destinados a extração. Foi preparada cavidade de acesso e feita ampliação coronária. Cerca de duas gotas de sangue obtidas por punção digital foram injetadas no canal. O comprimento eletrônico de trabalho (EWL) foi medido duas vezes antes (Grupo NB) e depois (Grupo WB) da injeção do sangue. O dente foi extraído e o comprimento real de trabalho (AWL) foi determinado. Os dados foram analisados com o teste de McNemar. As taxas de precisão a ±0,5 mm de Raypex 5 e Root ZX foram 88,9% and 91,5% no Grupo NB, e 83,3% e 86,2% para o Grupo WB, respectivamente. Não houve diferença significativa entre a precisão de cada um dos EFLs em ambos os grupos (p>0,05). Considerando os grupos NB e WB, não houve diferença significativa entre as precisões dos EFLs (p>0,05). A presença de sangue no canal radicular não influencou a precisão dos EFLs.

Introduction

Working length (WL) determination is one of the crucial factors for the success of root canal treatment 11. Ricucci D. Apical limit of root canal instrumentation and obturation, part 1. Literature review. Int Endod J 1998;3:384-393.. Its over- or under-estimation may give rise to the failure of endodontic treatment 22. Basmadjian-Charles, CL; Farge, P; Bourgeois, DM; Lebrun T. Factors influencing the long-term results of endodontic treatment: a review of the literature. Int Dent J 2002;52:81-86.. Ideally, the apical limit of canal preparation should be at the cementodentinal junction; however, this is a histologic landmark and cannot be determined precisely clinically 11. Ricucci D. Apical limit of root canal instrumentation and obturation, part 1. Literature review. Int Endod J 1998;3:384-393.. Therefore, the canal terminus is regarded by most clinicians as the least apical foramen or apical constriction, where there is minimal contact between the root canal filling material and periapical tissues 11. Ricucci D. Apical limit of root canal instrumentation and obturation, part 1. Literature review. Int Endod J 1998;3:384-393..

Radiographic methods have been routinely used for WL determination. However, they are not sufficiently reliable because of limitations such as file size, film position, image distortion, image magnification, tooth inclination, superimposition of bony structures and interpretation variability, which may provide inaccurate findings 33. Tamse, A; Kaffe, I; Fishel D. Zygomatic arch interference with correct radiographic diagnosis in maxillary molar endodontics. Oral Surg Oral Med Oral Pathol 1980;50:563-566.. In addition, radiographs show two dimensions of a three-dimensional structure, which might result in loss of data in some cases 44. El Ayouti, A; Weiger, R; Löst C. Frequency of overinstrumentation with an acceptable radiographic working length. J Endod 2001;27:49-52..

Sunada 55. Sunada I. New method for measuring the length of the root canal. J Dent Res 1962;41:375-387 developed the first electronic foramen locator (EFL) in clinical practice. The first EFLs needed calibration and were not accurate enough in the presence of electrolytes within the root canal 66. Kim, E; Lee SJ. Electronic apex locator. Dent Clin North Am 2004;48:35-54.. Since then, various electronic devices have been introduced based on different operating principles and electronic methods 77. Nekoofar, MH; Ghandi, MM; Hayes, SJ; Dummer PM. The fundamental operating principles of electronic root canal length measurement devices. Int Endod J 2006;39:595-609..

Raypex 5 (VDW, Munich, Germany) is a frequency-based EFL, which measures the impedance at the frequencies of 0.4 kHz and 8 kHz, but uses only one frequency at each time interval and measurements are based on the mean square values of signals 77. Nekoofar, MH; Ghandi, MM; Hayes, SJ; Dummer PM. The fundamental operating principles of electronic root canal length measurement devices. Int Endod J 2006;39:595-609.. The Root ZX (J. Morita Corp., Kyoto, Japan) is also a two-frequency EFL, which simultaneously measures the impedance at the same frequencies, calculates the quotient of the impedances and exhibits this quotient as a position of the file tip within the root canal 88. Kobayashi, C; Suda H. New electronic canal measuring device based on the ratio method. J Endod 1994;20:111-114..

The effects of some factors on the accuracy of EFLs 99. Tsesis, I; Blazer T; Ben-Izhack, G; Taschieri, S; Del Fabbro, M; Corbella S, et al.. The precision of electronic apex locators in working length determination: a systematic review and meta-analysis of the literature. J Endod 2015;41:1818-1823.,1010. Saatchi, M; Rahimi, I; Khademi, A; Farhad, AR; Nekoofar, MH; Dummer PM. Influence of tooth length on the accuracy of the Root ZX electronic apical foramen locator: an ex vivo study. Acta Odontol Scand 2015;73:101-106.,1111. Vasconcelos, BC; Alencar, Matos L; Pinheiro-Júnior, EC; Menezes, AS; Vivacqua-Gomes N. Ex vivo accuracy of three electronic apex locators using different apical file sizes. Braz Dent J 2012;23:199-204.,1212. de Vasconcelos, BC; Araúj, RB; Silva, FC; Luna-Cruz, SM; Duarte, MA; Oliveira Fernandes CA. In vivo accuracy of two electronic foramen locators based on different operation systems. Braz Dent J 2014;25:12-16. and comparisons between the accuracy of EFLs have been investigated 1313. Somma, F; Castagnola, R; Lajolo, C; Paternò Holtzman, L; Marigo L. In vivo accuracy of three electronic root canal length measurement devices: Dentaport ZX, Raypex 5 and ProPex II. Int Endod J 2012;45:552-556.,1414. Stöber, EK; de Ribot, J; Mercadé, M; Vera, J; Bueno, R; Roig M et al.. Evaluation of the Raypex 5 and the mini apex locator: an in vivo study. J Endod 2011;37:1349-1352.. The presence of blood within the root canal as an electrolyte material may also influence the accuracy of EFLs. To date, there have been few and controversial in vitro studies on the effect of the presence or absence of blood within the root canal on the accuracy of EFLs 1515. Bashar, A; Joshi, R; Alam M. Accuracy of electronic apex locator for determining the root canal length in presence of blood - an in vitro study. Bangladesh Med J 2009;37:15-18.,1616. He, L; Hu, TQ; Zhao, H; Lin, JQ; Li, P. Effect of four different solutions on the accuracy of electronic apex locators. Shanghai Kou Qiang Yi Xue 2008;17:304-307.,1717. Ebrahim, AK; Yoshioka, T; Kobayashi, C; Suda H. The effects of file size, sodium hypochlorite and blood on the accuracy of Root ZX apex locator in enlarged root canals: an in vitro study. Aust Dent J 2006;51:153-157.. However, there are no in vivo studies on this issue. Therefore, the aim of this in vivo study was to evaluate whether the presence of blood within the root canal influences the accuracy of the Raypex 5 and Root ZX foramen locators under clinical conditions.

Material and Methods

Forty single-canal teeth (14 maxillary incisors, 15 mandibular incisors, 4 maxillary second premolars and 7 mandibular premolars) from 21 patients (8 women and 13 men) with an age range of 38-62 years, scheduled for extraction, were included in this study. Because the pulp vitality does not affect the accuracy of EFLs 1818. Akisue, E; Gavini, G; Figueiredo JA. Influence of pulp vitality on length determination by using the Elements Diagnostic Unit and Apex Locator. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;104:e129-e32., teeth with necrotic (29 teeth) and vital pulp (11 teeth) were included in the study. Teeth with pulp calcification, open apices, prosthetic crowns, metal restorations, previous endodontic treatment and history of any trauma were not included. The Ethics Committee of Isfahan University of Medical Sciences approved the study design (No. 393124). Informed written consent was obtained from all the patients at the beginning of the study.

Medical/dental history and radiographic examination were obtained. The patients were asked to use Listerine mouthwash for 1 min; anesthesia was achieved and a dental dam was placed. The cusp tip or incisal edge was flattened with a diamond bur (818.FG.035; JOTA, Ruthi, Switzerland) to provide a reproducible reference point. An endodontic access cavity was prepared, and pulp tissue remnants were removed with #15 and #20 K-file (Dentsply-Maillefer, Ballaigues, Switzerland). Coronal enlargement was achieved with a nickel-titanium ProTaper SX rotary file (Dentsply Maillefer). The root canal was irrigated with 2.5% sodium hypochlorite solution and normal saline by a 27-gauge needle. In some vital teeth, a little bleeding from the root canal was controlled by irrigating with 2.5% sodium hypochlorite solution and waiting about 5 min. Electronic and actual working lengths were measured by an endodontist, in a way similar to a previous study 1919. Saatchi, M; Aminozarbian, MG; Hasheminia, SM; Mortaheb A. Influence of apical periodontitis on the accuracy of 3 electronic root canal length measurement devices: an in vivo study. J Endod 2014;40:355-359..

Electronic WL (EWL) measurement of each tooth by each device was established twice (before and after injecting blood into the root canal). First, as No Blood (NB) group, the canal was irrigated with normal saline solution; excess fluid was removed from the pulp chamber, but no attempt was made to dry the canals and then EWL was measured. Second, as With Blood (WB) group, the canal was dried with sterile paper points. Approximately 2 drops of blood were collected from each patient by finger prick in a sterile disposable micropipette (Blaubrand, Wertheim, Germany) and injected into the root canal space. The excess blood was removed from the pulp chamber, but no attempt was made to dry the canals and then EWL was measured. The Raypex 5 and Root ZX devices were used according to the manufacturers' instructions. The lip clip was attached to the patient's lip, and the file clip was connected to a #15 K-file. With the Raypex 5, the file was inserted into the root canal to the major apical foramen (red line) and then pulled back until the 3 green bars were observed in the display. With the Root ZX, the file was inserted into the root canal to the major apical foramen (''APEX'' mark and signal) and then pulled back until the display showed the 0.5-mm mark. Measurements were considered correct if the reading remained stable for at least 5 s. A silicone stop was then carefully adjusted to the flattened coronal reference point; the file was removed from the root canal and the distance between the file tip and the silicone stop was measured with a high-precision digital caliper (Mitutoyo Corp, Tokyo, Japan). Electronic measurements were repeated 3 times and the mean of the values was recorded as EWL.

For actual WL (AWL) measurement, the rubber dam was removed; the tooth was extracted and placed in 5.25% sodium hypochlorite for 1 h to remove any debris or organic tissue from the root surface and then rinsed under tap water. After that, a #15 K-file was inserted into the canal until the file tip could be observed through the major foramen at ×16 magnification by a dental operating microscope (OPMI Primo, Carl Zeiss, Jena, Germany). The file was then pulled back until the file tip was placed tangential to the major foramen. A silicone stop was adjusted to the same reference point; the file was removed from the root canal and the distance between the file tip and the silicone stop was measured with the same digital caliper. Then 0.5 mm was subtracted from this measurement. The measurements were repeated 3 times and the mean of the values was recorded as the AWL.

In each tooth, the AWL was subtracted from the EWL to define the distance between the file tip (EWL) and the point 0.5 mm coronal to the major foramen (AWL). Positive values defined measurements beyond the AWL (over) and negative values defined measurements short of the AWL (under). Data were evaluated using SPSS 20 (IBM, Armonk, NY, USA). The accuracy of each EAL within ±0.5 mm was compared between the NB and WB groups using the kappa value and McNemar's test. The relationship between the two variables "EALs" and "presence/absence of blood" was also evaluated using the kappa value and McNemar's test. Statistical significance was set at p<0.05.

Results

Four teeth were excluded from the study, two because of unreliable electronic measurements and two because of root fracture during extraction. Therefore, 36 teeth were included in the statistical analysis. The accuracy rates of Raypex 5 within the error range of ±0.5 mm in the NB and WB groups were 88.9% and 83.3%, respectively. For Root ZX, they were 91.5% and 86.2%, respectively (Table 1). There were no statistically significant differences between the NB and WB groups with regards to the accuracy of Raypex 5 (kappa=0.77; McNemar test=0.500) and Root ZX (kappa=0.72; McNemar's test=0.500). Moreover, considering the two groups of NB and WB, there were no significant differences in the accuracy of Raypex 5 and Root ZX (kappa=0.82; McNemar's test=0.500)

Table 1
Number (percentage) of electronic measurements relative to the actual working length

Discussion

The accuracy of frequency-dependent EFLs with a clinical tolerance of ±0.5 mm is approximately 65%-100% 66. Kim, E; Lee SJ. Electronic apex locator. Dent Clin North Am 2004;48:35-54.. Use of irrigating solutions such as normal saline, sodium hypochlorite and chlorhexidine is an important aspect of endodontic treatment. The influence of different irrigating solutions as electrolyte materials on the accuracy of EFLs has been investigated (20-23). Some authors reported that endodontic irrigants could affect the accuracy of EFLs 2121. Fan, W; Fan B; Gutmann, JL; Bian, Z; Fan, MW. Evaluation of the accuracy of three electronic apex locators using glass tubules. Int Endod J 2006;39:127-135.,2222. Özseze,r E; Inan, U; Aydin, U. In vivo evaluation of ProPex electronic apex locator. J Endod 2007;33:974-977.. Others found that EFLs performed well irrespective of the used irrigant 2020. Erdemir, A; Eldeniz, AU; Ari, H; Belli, S; Esener T. The influence of irrigating solutions on the accuracy of the electronic apex locator facility in the Tri Auto ZX handpiece. Int Endod J 2007;40:391-397.,2323. Gomes, S; Olive,r R; Macouzet, C; Mercade, M; Roig, M; Duran-Sindreu F. In vivo evaluation of the Raypex 5 by using different irrigants. J Endod 2012;38:1075-1077.. Besides, pulp extirpation during endodontic treatment results in bleeding in the root canal. Since blood is an electrolyte, it may influence the accuracy of EFLs. A review of the literature revealed that only three conflicting in vitro and not in vivo studies have been published on this issue (15-17). Hence, the purpose of this study was to evaluate the influence of blood in the root canal space on the accuracy of two well-known EFLs, the Raypex 5 and Root ZX, in vivo. Bashar et al. 1515. Bashar, A; Joshi, R; Alam M. Accuracy of electronic apex locator for determining the root canal length in presence of blood - an in vitro study. Bangladesh Med J 2009;37:15-18. used Foramatron D 10 EFL on 60 extracted maxillary and mandibular anterior teeth and claimed that WL measurement by the EFL in the presence of blood within the root canal remained mostly within a clinically acceptable range of ±0.5 mm. He et al. 1616. He, L; Hu, TQ; Zhao, H; Lin, JQ; Li, P. Effect of four different solutions on the accuracy of electronic apex locators. Shanghai Kou Qiang Yi Xue 2008;17:304-307. used Raypex 5 and TRRY EFL on 47 extracted single-rooted teeth and concluded that both EFLs could measure root canal length accurately despite the influence of blood within the root canal. Ebrahim et al. 1717. Ebrahim, AK; Yoshioka, T; Kobayashi, C; Suda H. The effects of file size, sodium hypochlorite and blood on the accuracy of Root ZX apex locator in enlarged root canals: an in vitro study. Aust Dent J 2006;51:153-157. used Root ZX on 36 extracted mandibular premolar teeth and reported that compared to sodium hypochlorite, the presence of blood, a file size close to the prepared canal diameter is required for accurate root length measurement. However, in this in vivo study were used Raypex 5 and Root ZX on 36 single-canal teeth and it was found that presence of blood within the root canal did not affect the accuracy of the EFLs. Differences between the results of different studies might be attributed to differences in device type, tooth type and study method.

Ex vivo and in vivo methods have been used to evaluate the accuracy of EFLs. Ex vivo methods were developed in which extracted teeth were immersed in an electrolyte material with electrical resistance similar to that of the periodontium. These methods have some advantages such as simplicity, ease of use, ability to have strict control and ability to test a great number of samples in a short period compared with in vivo methods. However, the disadvantages of these methods are the possibility of electrolyte media leakage through the apical foramen, which could result in premature readings 2424. Czerw, RJ; Fulkerson, MS; Donnelly, JC. An in vitro test of a simplified model to demonstrate the operation of electronic root canal measuring devices. J Endod 1994;20:605-606. and inability to simulate completely the clinical conditions 2525. Fouad AF. The use of electronic apex locators in endodontic therapy. Int Endod J 1993;26:13-14.. Therefore, the results of ex vivo studies may raise doubts about their clinical relevance. Thus, considering the ethical issues, an in vivo method was used for the purpose of this research.

Cleaning and shaping of the root canal should be limited to the canal terminus. It is considered by most clinicians as the apical constriction or the minor apical foramen, which is located at 0.5-1 mm coronal to the major apical foramen 11. Ricucci D. Apical limit of root canal instrumentation and obturation, part 1. Literature review. Int Endod J 1998;3:384-393.. Therefore, the apical landmark was considered at 0.5 mm coronal to the major apical foramen. Moreover, a range of ±0.5 mm from the apical landmark was considered acceptable for the electronic measurements, based on similar previous studies 1919. Saatchi, M; Aminozarbian, MG; Hasheminia, SM; Mortaheb A. Influence of apical periodontitis on the accuracy of 3 electronic root canal length measurement devices: an in vivo study. J Endod 2014;40:355-359.,2323. Gomes, S; Olive,r R; Macouzet, C; Mercade, M; Roig, M; Duran-Sindreu F. In vivo evaluation of the Raypex 5 by using different irrigants. J Endod 2012;38:1075-1077.. Although EFLs detect the major apical foramen and they are not able to detect the root apex or apical constriction, they are generally called "electronic apex locator". Therefore, the use of an "electronic apical foramen locator" or simply "EFL" may be more appropriate 77. Nekoofar, MH; Ghandi, MM; Hayes, SJ; Dummer PM. The fundamental operating principles of electronic root canal length measurement devices. Int Endod J 2006;39:595-609.,1010. Saatchi, M; Rahimi, I; Khademi, A; Farhad, AR; Nekoofar, MH; Dummer PM. Influence of tooth length on the accuracy of the Root ZX electronic apical foramen locator: an ex vivo study. Acta Odontol Scand 2015;73:101-106..

In this study, the accuracy rates of Raypex 5 and Root ZX decreased slightly in the presence of blood in the root canal. Although a decrease in the accuracy of the EFLs in the presence of blood was not statistically significant, it is advisablethat clinicians consider the possibility of decrease.

Within the limitations of this study, the accuracy of Raypex 5 and Root ZX EFLs was not influenced by the presence of blood in the root canal space.

Acknowledgements

This study was supported by Isfahan University of Medical Sciences Research Grant # 393124.

References

  • 1
    Ricucci D. Apical limit of root canal instrumentation and obturation, part 1. Literature review. Int Endod J 1998;3:384-393.
  • 2
    Basmadjian-Charles, CL; Farge, P; Bourgeois, DM; Lebrun T. Factors influencing the long-term results of endodontic treatment: a review of the literature. Int Dent J 2002;52:81-86.
  • 3
    Tamse, A; Kaffe, I; Fishel D. Zygomatic arch interference with correct radiographic diagnosis in maxillary molar endodontics. Oral Surg Oral Med Oral Pathol 1980;50:563-566.
  • 4
    El Ayouti, A; Weiger, R; Löst C. Frequency of overinstrumentation with an acceptable radiographic working length. J Endod 2001;27:49-52.
  • 5
    Sunada I. New method for measuring the length of the root canal. J Dent Res 1962;41:375-387
  • 6
    Kim, E; Lee SJ. Electronic apex locator. Dent Clin North Am 2004;48:35-54.
  • 7
    Nekoofar, MH; Ghandi, MM; Hayes, SJ; Dummer PM. The fundamental operating principles of electronic root canal length measurement devices. Int Endod J 2006;39:595-609.
  • 8
    Kobayashi, C; Suda H. New electronic canal measuring device based on the ratio method. J Endod 1994;20:111-114.
  • 9
    Tsesis, I; Blazer T; Ben-Izhack, G; Taschieri, S; Del Fabbro, M; Corbella S, et al.. The precision of electronic apex locators in working length determination: a systematic review and meta-analysis of the literature. J Endod 2015;41:1818-1823.
  • 10
    Saatchi, M; Rahimi, I; Khademi, A; Farhad, AR; Nekoofar, MH; Dummer PM. Influence of tooth length on the accuracy of the Root ZX electronic apical foramen locator: an ex vivo study. Acta Odontol Scand 2015;73:101-106.
  • 11
    Vasconcelos, BC; Alencar, Matos L; Pinheiro-Júnior, EC; Menezes, AS; Vivacqua-Gomes N. Ex vivo accuracy of three electronic apex locators using different apical file sizes. Braz Dent J 2012;23:199-204.
  • 12
    de Vasconcelos, BC; Araúj, RB; Silva, FC; Luna-Cruz, SM; Duarte, MA; Oliveira Fernandes CA. In vivo accuracy of two electronic foramen locators based on different operation systems. Braz Dent J 2014;25:12-16.
  • 13
    Somma, F; Castagnola, R; Lajolo, C; Paternò Holtzman, L; Marigo L. In vivo accuracy of three electronic root canal length measurement devices: Dentaport ZX, Raypex 5 and ProPex II. Int Endod J 2012;45:552-556.
  • 14
    Stöber, EK; de Ribot, J; Mercadé, M; Vera, J; Bueno, R; Roig M et al.. Evaluation of the Raypex 5 and the mini apex locator: an in vivo study. J Endod 2011;37:1349-1352.
  • 15
    Bashar, A; Joshi, R; Alam M. Accuracy of electronic apex locator for determining the root canal length in presence of blood - an in vitro study. Bangladesh Med J 2009;37:15-18.
  • 16
    He, L; Hu, TQ; Zhao, H; Lin, JQ; Li, P. Effect of four different solutions on the accuracy of electronic apex locators. Shanghai Kou Qiang Yi Xue 2008;17:304-307.
  • 17
    Ebrahim, AK; Yoshioka, T; Kobayashi, C; Suda H. The effects of file size, sodium hypochlorite and blood on the accuracy of Root ZX apex locator in enlarged root canals: an in vitro study. Aust Dent J 2006;51:153-157.
  • 18
    Akisue, E; Gavini, G; Figueiredo JA. Influence of pulp vitality on length determination by using the Elements Diagnostic Unit and Apex Locator. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;104:e129-e32.
  • 19
    Saatchi, M; Aminozarbian, MG; Hasheminia, SM; Mortaheb A. Influence of apical periodontitis on the accuracy of 3 electronic root canal length measurement devices: an in vivo study. J Endod 2014;40:355-359.
  • 20
    Erdemir, A; Eldeniz, AU; Ari, H; Belli, S; Esener T. The influence of irrigating solutions on the accuracy of the electronic apex locator facility in the Tri Auto ZX handpiece. Int Endod J 2007;40:391-397.
  • 21
    Fan, W; Fan B; Gutmann, JL; Bian, Z; Fan, MW. Evaluation of the accuracy of three electronic apex locators using glass tubules. Int Endod J 2006;39:127-135.
  • 22
    Özseze,r E; Inan, U; Aydin, U. In vivo evaluation of ProPex electronic apex locator. J Endod 2007;33:974-977.
  • 23
    Gomes, S; Olive,r R; Macouzet, C; Mercade, M; Roig, M; Duran-Sindreu F. In vivo evaluation of the Raypex 5 by using different irrigants. J Endod 2012;38:1075-1077.
  • 24
    Czerw, RJ; Fulkerson, MS; Donnelly, JC. An in vitro test of a simplified model to demonstrate the operation of electronic root canal measuring devices. J Endod 1994;20:605-606.
  • 25
    Fouad AF. The use of electronic apex locators in endodontic therapy. Int Endod J 1993;26:13-14.

Publication Dates

  • Publication in this collection
    May-Jun 2016

History

  • Received
    04 Dec 2015
  • Accepted
    28 Mar 2016
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