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ORIGINAL RESEARCH ARTICLE  
Year : 2017  |  Volume : 20  |  Issue : 4  |  Page : 264-268
A comparative clinical evaluation of accuracy of six apex locators with intraoral periapical radiograph in multirooted teeth: An in vivo study


1 Department of Conservative Dentistry and Endodontics, PMNM Dental College and Hospital, Bagalkot, Karnataka, India
2 Department of Conservative Dentistry and Endodontics, H. K. E. Society's S. N Institute of Dental Science and Research, Gulbarga, Karnataka, India

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Date of Submission08-Apr-2017
Date of Decision02-Nov-2017
Date of Acceptance07-Nov-2017
Date of Web Publication24-Nov-2017
 

   Abstract 

Aim: The purpose of this clinical study was to compare and clinically, to evaluate the accuracy of six apex locators with intra oral periapical (IOPA) radiograph in multirooted teeth.
Materials and Methods: A total of 90 multirooted teeth (maxillary and mandibular molars) with irreversible, infected or necrotic pulp tissue and completely formed roots were included in this study and were divided randomly into six groups (Root ZX II, Raypex 6, I-Root, Romiapex A-15, Sybron Endo Mini and Root ZX mini). The working length was determined using six different apex locators, and the accuracy of the apex locators was compared with IOPA radiographs, to be categorized as accurate, short, and long or beyond.
Results: A total of 270 canals were evaluated, of which 233 (86.3%) canals exhibited acceptable working length, 28 (10.4%) canals exhibited short working length, and only 9 (3.3%) canals exhibited working length beyond the apex. There were a statistically significant results in all the groups (P < 0.05) and the comparison between the groups was statistically insignificant.
Conclusion: The repeatability with that of apex locators is of great advantage, but the information gained from the radiographs cannot be obtained by any other means. Therefore, it is recommended that radiograph and apex locators are the best combinations in accurately determining the working length and the successful endodontics.

Keywords: Apex locators; intraoral periapical radiographs; multirooted teeth; radiographic apex; working length

How to cite this article:
Saraf PA, Ratnakar P, Patil TN, Penukonda R, Kamatagi L, Vanaki SS. A comparative clinical evaluation of accuracy of six apex locators with intraoral periapical radiograph in multirooted teeth: An in vivo study. J Conserv Dent 2017;20:264-8

How to cite this URL:
Saraf PA, Ratnakar P, Patil TN, Penukonda R, Kamatagi L, Vanaki SS. A comparative clinical evaluation of accuracy of six apex locators with intraoral periapical radiograph in multirooted teeth: An in vivo study. J Conserv Dent [serial online] 2017 [cited 2021 Oct 28];20:264-8. Available from: https://www.jcd.org.in/text.asp?2017/20/4/264/219193

   Introduction Top


The removal of infected pulp tissue, necrotic material, and microorganisms from the root canal system is essential for endodontic treatment success. This can be achieved only if the length of the root canal is determined accurately.[1]

Working length is defined as the distance from a coronal reference point to the point at which canal preparation and filling should terminate.[2] A correct working length is a critical factor for the endodontic success. Failure to determine the proper root canal working length during root canal treatment may compromise the treatment result.[3] To determine the working length, a number of techniques, including tactile sensation, radiographs, and electronic apex locators are routinely used in clinics.[4]

Conventionally, conventional radiographs used to determine the working length which provides information about the canal anatomy and surrounding tissues.[5] Radiographs are advantageous as the information they furnish, cannot be obtained from any other source and its value is not diminished by a critical appraisal of its limitations.[6] However, the accurate determination of root canal length radiographically is hindered due to anatomical variations, interference of anatomical structures, or errors in projection.[7] Super imposition, anatomy interferences, distortion, shortening and elongation, interpretation variability, and lack of three-dimensional representation affect the correct interpretation of the images.[2],[5]

These factors have stimulated the development of electronic root length measuring devices (apex locators), which accurately report the foramen or more precisely an area between the minor and major foramen diameter.[7]

Numerous electronic apex locating devices have been introduced since the 1960s. In 1962, Sunada demonstrated that the electrical resistance between the periodontal ligament and oral mucosa has a constant value that can be measured. As a result, some devices were developed for use as clinical aids in apex location. However, many devices often performed unpredictably from patient to patient.[8]

The ROOT ZX (J. Morita Corp., Kyoto, Japan) has a high level of precision because of the introduction of the ratio method and the subsequent development of the self-calibration. Root ZX II which works with the same principle of the original Root ZX, which has been subjected to several studies showing a high level of reliability. Blood, electrolytes or other substances do not impair its reliability.[3]

Root ZX mini also works according to the proven ratio technique as that of Root ZX and Root ZX II. This involves measuring the impedances of two frequencies (400 Hz and 8 kHz) to provide an absolutely precise length measurement.

Creation of a steady algorithm for adapting the method for measuring the working length of the root canal depending on the canal's moisture characteristic has been implemented in the apex locator of the so-called “sixth generation”– the adaptive type RAYPEX-6.[9]

I-Root (S-Denti, Seoul, Korea) I-Root was developed and upgraded based on the technology of e-Magic finderapex locator which operates on dual frequency ratio based method.[10]

Romiapex A-15 (Romidan Ltd, Kiryat Ono, Israel) measure the working length by calculating the mean square root values of the impedance at two different frequencies (0.5 and 8.0 kHz), measured separately. The device compares the results obtained with reference values positions. Thus, the RomiApex A-15 operate by detecting the energy of the signal, rather than its amplitude.[11]

Sybron Endo's Mini Apex Locator, according to the manufacturers, despite its compact size, is rugged and durable. It uses a sophisticated, multifrequency measurement system, an all-digital signal and an 80% shorter cable than other apex locators. The manufacturer claims that this all adds up to increased signal integrity, easy operation, and consistently reliable measurements.[3]

Electronic apex locators reduce the number of radiographs required and are recommended to complement and assist radiographic methods of working length determination.[12] Radiographic verification of electronic working length (EWL) is essential because in some clinical situations apex locators give incorrect readings.[13] To achieve the highest degree of accuracy in working length determination, a combination of several methods should be used.[14],[15]

The information regarding their accuracy in root canal length determination in multirooted teeth is limited. Therefore, the purpose of this clinical study was to compare and clinically evaluate the accuracy of six apex locators with intraoral periapical (IOPA) radiograph in multirooted teeth.


   Materials and Methods Top


The study was conducted in the Department of Conservative Dentistry and Endodontics. Ethical clearance was obtained from the Institutional Ethical Committee. Informed consent of each patient was obtained after explaining the clinical procedure.

Ninety multirooted teeth (maxillary and mandibular molars) with irreversible, infected or necrotic pulp tissue and completely formed roots were included in the study. Patients using cardiac pace makers, who had a contributory medical history and the teeth with no apical patency, radiographic evidence of resorption and bone loss were excluded from the study.

Tooth was anesthetized and isolated with a rubber dam. Endodontic access cavity was made, and a straight-line access to the root canals was achieved. The orifices of the root canals were irrigated with sodium hypochlorite solution and excess was removed from the pulp chamber by using cotton pellets. No attempt was made to clean debris or pulp tissue remnants before introducing K file.

Following the preparation of adequate access cavity, apex locator was used to determine the EWL.

Maxillary and mandibular multirooted teeth were randomly allocated to following study Groups. Group I: Working length determined with ROOT ZX II apex locator, Group II: Working length determined with Root ZX mini apex locator, Group III: Working length determined with the RAYPEX-6apex locator. Group IV: Working length determined with I-Root apex locator. Group V: Working length determined with Romiapex-A15 apex locator. Group VI: Working length determined with Sybron Endo mini apex locator.

Electronic measurements were made with instrument size selected according to the canal and the new file with firm silicone rubber stopper for every canal was used which was advanced till the apex locator indicated the apex or apical constriction has reached. The rubber stopper was set to the reference point when there was a stable reading for at least 5 s. The values were recorded with the file in the canal. Working length radiograph was taken using bisecting angle technique. Based on the position of the file tip to the radiographic apex on the IOPA radiograph, the samples were categorized using the following scoring criteria.[16]

  • Acceptable = 0–1 short
  • Short = >1 mm short
  • Long/Beyond = Beyond the apex


The data were analyzed statistically using Fisher's exact test with SPSS software version 19.00 (IBM Corp, Armonk, NY, USA).


   Results Top


A total of 90 teeth with 270 canals were evaluated in this study. Based on the scoring criteria, out of 270 canals 233 canals exhibited acceptable working length, 28 canals exhibited short working length, and only 9 canals exhibited working length beyond the apex [Table 1] and [Figure 1].
Table 1: Accuracy of six different apex locators

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Figure 1: Accuracy of six different apex locators

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ROOT ZX II had an accuracy of 97.8%, RAYPEX-6 had an accuracy of 95.6%, Romiapex had an accuracy of 95.6%, I-Root had an accuracy of 93.3%, Sybron Endo Mini had an accuracy of 73.3%, and Root ZX Mini had an accuracy of 62.2%, respectively. There were a statistically significant results in all the groups (P < 0.05) and the comparison between the groups was statistically insignificant [Table 2] and [Figure 1].
Table 2: Arch wise comparison of each apex locators

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The archwise comparison, made between the maxillary and mandibular multirooted teeth was statistically insignificant, indicating the position of the teeth did not affect the determination of the working length [Table 2].


   Discussion Top


Apex locators have advantages over radiographic methods; EWL determination with apex locators is easier, faster and can be indefinitely repeated without exposure to radiation. Moreover, modern apex locators can locate not only the apical foramen but also, in contrast to radiographic methods, the apical constriction, which is an optimal endpoint for root canal preparation and filling. The accuracy of apex locators is higher when compared with that of the radiographic methods.[13]

Nevertheless, it has been shown that a higher accuracy can be reached when both radiographic and EWL determination is performed. A working length radiograph after EWL determination can reduce over-instrumentation and provide valuable diagnostic information. Radiographic verification of the EWL is essential because in some clinical situations apex locators give incorrect readings.[13]

The method used in the present study accurately simulates the clinical condition, unlike previous works in which the treated teeth were later extracted, and the position of the file tip was then exposed.[17] The method used in this study enabled a straightforward examination of the new electronic apex locator with conventional IOPA radiograph.

Multirooted teeth were selected for the study because the degree of apical foramen deviation is more in posterior teeth. It has also been reported that as the curvature of the apical part of the root increases, the chances for erroneous radiographic working length also increased. Palatal and mesiobuccal roots of maxillary molars were associated with the highest incidence of inaccurate radiographic working length compared with other roots in vitro and in vivo.[16]

A conventional IOPA radiograph was used to evaluate the accuracy as a direct measurement on the radiographs has proven to be very accurate. This direct method was advocated on the premise that distortion and calculation errors are small enough to be of no practical consequence.[18] An in vitro comparison of conventional and digital images showed that digital images resulted in an overestimation of the actual file length by 2.81%–7.58%, whereas the same value for conventional images was only 1.13%.[16] A radiograph is the only universally accepted, available and meaningful method of length adequacy assessment in the clinic.[5]

Working length radiograph was taken using bisecting angle technique as it is the most common radiographic technique and the presence of a rubber dam, rubber dam clamp, and the root canal instruments may complicate by impairing proper receptor positioning and aiming cylinder angulations with paralleling technique.[19] The radiographic working length produced by both paralleling and bisecting angle technique has been compared and concluded that comparable working lengths and the slightly better performance of the former would be clinically irrelevant.[17]

The performance of electronic apex locators has conventionally been afforded some latitude of acceptable error in locating the apex. An error tolerance of +/-1.0 mm is deemed clinically acceptable.[8] In the present study, we have determined a clinical tolerance of 0-1 mm of the radiographic apex as the acceptable range.

The in vivo accuracy of apex locators ranges from a low of 15% to a high of 93.4% and as such cannot be relied on the sole mechanism for working length location. Contemporary units have degrees of accuracy that range from 83% to 93.4%. Hence, to achieve consistent success with this approach to working length determination, the astute clinician will integrate the use of instruments with high quality, standardized diagnostic radiographs.[20]

In the present study, accuracy of 97.8% was obtained using Root ZX II which is in accordance with the in vitro study producing values to a precision of 97.37%.[3] The accuracy of Raypex 6 is 95.6% which is in accordance with study conducted by Aydin et al. with an accuracy of 88.2%.[4] The accuracy obtained with Sybron Endo Mini apex locator was 73.3% which was comparable with that of the study conducted by Vasconcelos et al. in which the accuracy was 73.5%.[11] The accuracy attained with Root ZX mini was 62.2% which is in accordance with that of the study conducted by da Silva et al. with an accuracy of 56.2%.[21] According to the in vitro study by Sakkir et al. there is no statistically significant difference between I-Root and Root ZX II, which correlates with the present study wherein the accuracy obtained is 93.3% which is comparable with that of Root ZX II.[10] The accuracy of Romiapex A-15 was 95.6% which is in accordance with the study comparing the accuracy of Root ZX II and Romiapex A-15 by Filho et al.[22]

In the present study, the accuracy of Root ZX mini and Sybron Endo mini was inferior when compared to other apex locators. Determination of apical constriction, associated with complete disruption of apical constriction, the shape of root canals and their configuration varies with different apex locators. This may be the reason for inaccurate readings with respect to Root ZX mini and Sybron Endo mini apex locators. Furthermore, electroconductivity of the dentine walls, the presence of apical ramifications may also influence the accuracy of EALs.[4]


   Conclusion Top


Root canal procedures should be limited within the confines of the root canal, with the logical endpoint for preparation and obturation being the narrowest part of the canal. Therefore, it is necessary to apply a rational thought in combining radiography and electronic devices to arrive at the desired apical terminus of the endodontic preparation and achieve the highest degree of accuracy in working length determination.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

1.
Khandewal D, Ballal NV, Saraswathi MV. Comparative evaluation of accuracy of 2 electronic apex locators with conventional radiography: An ex vivo study. J Endod 2015;41:201-4.  Back to cited text no. 1
    
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D'Assunção FL, de Albuquerque DS, Salazar-Silva JR, de Queiroz Ferreira LC, Bezerra PM. The accuracy of root canal measurements using the Mini Apex Locator and Root ZX-II: An evaluation in vitro. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;104:e50-3.  Back to cited text no. 3
    
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Aydin U, Karataslioglu E, Aksoy F, Yildirim C.In vitro evaluation of Root ZX and Raypex 6 in teeth with different apical diameters. J Conserv Dent 2015;18:66-9.  Back to cited text no. 4
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Leonardo MR, Silva LA, Nelson-Filho P, Silva RA, Raffaini MS. Ex vivo evaluation of the accuracy of two electronic apex locators during root canal length determination in primary teeth. Int Endod J 2008;41:317-21.  Back to cited text no. 7
    
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11.
Vasconcelos BC, Bueno Mde M, Luna-Cruz SM, Duarte MA, Fernandes CA. Accuracy of five electronic foramen locators with different operating systems: An ex vivo study. J Appl Oral Sci 2013;21:132-7.  Back to cited text no. 11
    
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ElAyouti A, Dima E, Ohmer J, Sperl K, von Ohle C, Löst C, et al. Consistency of apex locator function: A clinical study. J Endod 2009;35:179-81.  Back to cited text no. 13
    
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Thomas MS, Acharaya S, Kundabala M. A comparative evaluation of the accuracy of third generation electronic apex locator (root zx) and conventional radiography to determine working length – An in vivo study. Endodontology 2008;20:14-21.  Back to cited text no. 14
    
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Moshonov J, Slutzky-Goldberg I, Maor R, Shay B, Peretz B.In vivo evaluation of Apex NRG, a new Apex locator, and its comparison with root ZX. Endod Pract 2005.  Back to cited text no. 17
    
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Versteeg KH, Sanderink GC, van Ginkel FC, van der Stelt PF. Estimating distances on direct digital images and conventional radiographs. J Am Dent Assoc 1997;128:439-43.  Back to cited text no. 18
    
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21.
da Silva TM, Alves FR. Ex vivo accuracy of Root ZX II, Root ZX Mini and RomiApex A-15 apex locators in extracted vital pulp teeth. J Contemp Dent Pract 2014;15:312-4.  Back to cited text no. 21
    
22.
Filho EM, Rizzi CD, de Oliveira DS, Filho PN, da Silva RA, da Silva AB. New electronic apex locator Roamiapex A-15 presented accuracy for working length determination in permanent teeth. Dentistry 3000 2014;2:1-4.  Back to cited text no. 22
    

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Correspondence Address:
Prahlad A Saraf
Department of Conservative Dentistry and Endodontics, PMNM Dental College and Hospital, Bagalkot, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JCD.JCD_131_17

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