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 Table of Contents  
Year : 2017  |  Volume : 29  |  Issue : 2  |  Page : 142-145

Do mobile phones cause interference on electronic apex locators? An in vitro study

Maitri College of Dentistry and Research Center, Anjora, Chhattisgarh, India

Date of Web Publication6-Nov-2017

Correspondence Address:
Aditi Subodh Jain
D 13, Kailash Nagar, Rajnandgaon, Chhattisgarh - 491 441
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/endo.endo_5_17

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Aim: The purpose of this study was to evaluate the interference of smart phone (Iphone 5s) during working length determination on electronic apex locators (Root ZX and NSK ipex II) function in vitro.
Materials and Methods: Two EALs: Root ZX (J. Morita Co., Tustin, CA, U.S.A.) & NSK ipex II were tested for any interference with smart phone during working length determination. The effect of cellular phones on electronic working length (EWL) was determined under 2 experimental settings: 1) in a multispeciality set up with good signal strength 2) in a closed room with poor signal strength and Five conditions a) Control group - No mobile phone in the room b) In close contact with EAL in safe mode c) in close contact with EAL for 30 seconds d) Phone kept at a distance of 35 cm from EAL in safe mode e) Phone kept at a distance of 35 cm from EAL in calling mode for a duration of 30 seconds. The readingswas scored from 1 to 3 and the data was subjected for statistical analysis.
Results: Statistical significant difference was obtained when an intergroup comparison was made using two- way repeated analysis of variance.
Conclusion: Electronic apex locators tested did not cause inhibition or interfere with mobile phones.

Keywords: Electronic apex locator, smart phone, Electromagnetic interference

How to cite this article:
Jain AS, Asrani H, Singhal AC, Asrani A, Deshmukh P, Jain D. Do mobile phones cause interference on electronic apex locators? An in vitro study. Endodontology 2017;29:142-5

How to cite this URL:
Jain AS, Asrani H, Singhal AC, Asrani A, Deshmukh P, Jain D. Do mobile phones cause interference on electronic apex locators? An in vitro study. Endodontology [serial online] 2017 [cited 2021 Apr 11];29:142-5. Available from: https://www.endodontologyonweb.org/text.asp?2017/29/2/142/217718

  Introduction Top

As per the American Association of Endodontists, approximately 16 million root canal treatments were performed every year, so it is an indispensable part of dental practice.[1] One of the requirements for effective endodontic therapy is the estimation of the precise working length (WL). The advancement of the electronic apex locator (EAL) has helped make the determination of WL of a tooth more exact and predictable when compared with the conventional radiographic method, so making them utilized worldwide.[2]

It is known that wireless communication devices, such as iPods, ultrasonic scalers, electronic pulp testers, and electrosurgery units, emit radiofrequency signals as they have the potential to interfere with cardiac pacemaker devices and implantable defibrillators.[3] The use of cellular phones has been banned in many hospitals and clinics to impede electromagnetic interference with medical devices.

According to the technical support, documents of EALs such as Propex II (Dentsply Maillefer, Switzerland) and Root ZX (J. Morita Corp., Tokyo, Japan) state that cellular phones can cause interference with an accurate reading of the EAL and should not be used.[4],[5],[6] However, there is very little literature available on the potential interference of whether mobile phones can be used in proximity to EALs.

The point of this paper is to identify the possible sources of interference using mobile phone in different experimental settings while determining WL in dental clinics which can unfavorably interfere with the activity of EAL and to provide some guidelines for safe dental practice in this high-risk group.

Hence, the aim of this study is to evaluate the constancy of two EALs in different experimental settings when placed in contact and in adjacency with a mobile phone (Apple iPhone 5s, Apple Inc. Cupertino, California).

  Materials and Methods Top

Sample preparation

Forty extracted human single-rooted premolars with mature apices were selected for this study and stored in normal saline. Tooth with incompletely formed apex or resorption or those with fractures/cracks were excluded from the study. All the samples were standardized to 15 mm length by decoronation using a steel disc so as to provide a reproducible reference point.

Electronic apex locator

Two different EALs were used in this study:

  1. Root ZX (J. Morita Corp, Tokyo, Japan)
  2. NSK iPex II.

Mobile phone

Apple iPhone 5s, Apple Inc. Cupertino, California was used in this study.

Experimental setting

The experiment was carried out in two different settings, one in a multispecialty clinic and other in a closed room so as to check whether the electronic working length differed between the two settings:

  1. In a multispecialty clinic with excellent strength where Bluetooth, WiFi, and general packet radio service (GPRS) were activated:

    • Dental students and assistants with cellular phones in safe mode in proximity of cubicle (control group)
    • Mobile phone in close contact with EAL in safe mode
    • Mobile phone in close contact with EAL for 30 s
    • Mobile phone kept at a distance of 35 cm from EAL in safe mode
    • Mobile phone kept at a distance of 35 cm from EAL in calling mode for 30 s.

  2. In a closed room with weak signal strength and where Bluetooth, WiFi, and GPRS were inactivated:

    • Control group – no mobile phone in the room
    • Mobile phone in close contact with EAL in safe mode
    • Mobile phone in close contact with EAL for 30 s
    • Mobile phone kept at a distance of 35 cm from EAL in safe mode
    • Mobile phone kept at a distance of 35 cm from EAL in calling mode for 30 s.

Access cavity was prepared by airotor using a #4 high-speed round carbide bur with water spray. After negotiating canal, root canal patency was established by placing a K-File #10 (Mani Inc., Tokyo, Japan). The WL was determined with the help of magnifying lens by placing the stainless steel K-File #10 inside the canal until its tip has been just visible at the apical foramen. Endo block was used to calculate the length. The WL was calculated to be 0.5 mm less than the length obtained by this initial file. Each measurement was repeated three times and the mean value was calculated.

The teeth were then embedded up to the cementoenamel junction in freshly mixed alginate (Zelgan Plus, Dentsply, USA) prepared according to the manufacturer's instructions and poured into a plastic mold. Simultaneously, the lip clip of the EALs was also inserted into the mold. The file with the previously calculated length was inserted into the tooth, then was pushed beyond the 0 reading on the EAL display and withdrawn slightly until the zero reading was displayed indicating apical patency. This reading was confirmed by the audible sound emitted from the EAL [Figure 1] and [Figure 2]. The readings were taken in accordance with the manufacturer's instruction and all measurements were recorded using a measuring scale.
Figure 1: Model connected to electronic apex locator with mobile phone placed in intimate contact

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Figure 2: Model connected to electronic apex locator with mobile phone placed in intimate contact

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Scoring criteria:[7]

  1. Immediate and clear audible signal emitted from EAL for 5 s
  2. Audible signal emitted from EAL for 5 s but after one attempt
  3. Audible signal emitted from EAL for 5 s but after two attempts.

  Results Top

The data obtained were statistically analyzed and compared using two-way repeated analysis of variance. The level of significance was set at P < 0.05. Under all the experimental settings, no background noise was detected and readings of EAL were stable. No statistically significant differences were obtained between the two groups [Table 1]. When a cellular phone is placed under different experimental conditions, no statistically significant difference was obtained in a closed room among all the two different apex locators [Table 2].
Table 1: Two-way analysis of variance for both electronic apex locator 1 (Root ZX) and both electronic apex locator 2 (NSK iPex II)

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Table 2: Mean values of working length for each condition

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  Discussion Top

Thisin vitro study evaluated the potential for interference of EAL while determining WL in contact with a smartphone. The apex locator used in this study was Root ZX and NSK iPex II. Apex locators are based on electrical principles rather than the biological characteristics of tissues. Therefore, in anin vitro study, the extracted teeth must be immersed in a medium with electrical resistance properties similar to those of the periodontium.[8],[9],[10] The alginate used in this study was found to be appropriate and the technique has been shown to be reliable in previous studies.

Different experimental conditions were used in this study. The experiment 1 was conducted in a multispecialty clinic to prevent any electronic interference and also Wifi, GPRS, and Bluetooth networks were inactivated contrary experimental setting 2 was carried out with excellent signal strength where Wifi, GPRS, and Bluetooth networks were activated.

Under the experimental conditions, the EAL showed good stability and reliability. The electromagnetic impedance between mobile phones and medical devices generally occurs only when the mobile phones are placed in proximity to the medical devices.[11],[12],[13],[14] Cardiac pacemaker interference with mobile phone is not a time-dependent phenomenon. A given stimulus either does or does not interfere with the normal pacing.[15] Therefore, a testing interval of 25–30 s was deemed satisfactory for this study.[16] These findings support the case report published by Beach et al.,[17] showing the use of an EAL in a pacemaker patient without clinical incident.

The results of this study demonstrated that there is no connection between phone utilize and electronic WL determination. Under all the test conditions, the EAL indicated good dependability and stability. This study concluded that the presence of cellular phone in proximity or at a distance from the EAL does not impact the readings of EALs. Thus, mobile phones can be utilized as a part of a dental operatory during root canal therapy without the danger of electromagnetic impedance between wireless and EAL.

The results obtained by evaluating two apex locators (Root Zx and Propex) showed that they do not cause any interference with the pacemaker function.[18],[19],[20],[21],[22],[23],[24] These findings support the case report published by Wood and Ellenbogen.[9]

The literature with respect to this topic is still scanty and needs more long-termin vivo studies to decide the real impacts of potential interference of whether mobile phones can be used in proximity to EALs.

  Conclusion Top

From the results of the presentin vitro study, it may be concluded,

  1. The tested EAL does not interfere with smartphone
  2. In dental clinics during electronic WL determination, mobile phones can be used without the phobia of causing electromagnetic interference.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Fouad AF, Reid LC. Effect of using electronic apex locators on selected endodontic treatment parameters. J Endod 2000;26:364-7.  Back to cited text no. 1
Kobayashi C. Electronic canal length measurement. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79:226-31.  Back to cited text no. 2
Nahmias Y, Aurelio JA, Gerstein H. Expanded use of the electronic canal length measuring devices. J Endod 1983;9:347-9.  Back to cited text no. 3
Chong BS, Pitt Ford TR. Apex locators in endodontics: Which, when and how? Dent Update 1994;21:328-30.  Back to cited text no. 4
Baranchuk A, Kang J, Shaw C, Campbell D, Ribas S, Hopman WM, et al. Electromagnetic interference of communication devices on ECG machines. Clin Cardiol 2009;32:588-92.  Back to cited text no. 5
Hurstel J, Guivarc'h M, Pommel L, Camps J, Tassery H, Cohen S, et al. Do cell phones affect establishing electronic working length? J Endod 2015;41:943-6.  Back to cited text no. 6
Klein AA, Djaiani GN. Mobile phones in the hospital – Past, present and future. Anaesthesia 2003;58:353-7.  Back to cited text no. 7
Wallin MK, Marve T, Hakansson PK. Modern wireless telecommunication technologies and their electromagnetic compatibility with life-supporting equipment. Anesth Analg 2005;101:1393-400.  Back to cited text no. 8
Wood MA, Ellenbogen KA. Cardiac pacemakers from the patient's perspective. J Am Heart Assoc 2002;105:2136-8.  Back to cited text no. 9
Tandogan I, Temizhan A, Yetkin E, Guray Y, Ileri M, Duru E, et al. The effects of mobile phones on pacemaker function. Int J Cardiol 2005;103:51-8.  Back to cited text no. 10
Simon AB, Linde B, Bonnette GH, Schlentz RJ. The individual with a pacemaker in the dental environment. J Am Dent Assoc 1975;91:1224-9.  Back to cited text no. 11
Lawrentschuk N, Bolton DM. Mobile phone interference with medical equipment and its clinical relevance: A systematic review. Med J Aust 2004;181:145-9.  Back to cited text no. 12
Hayes DL, Wang PJ, Reynolds DW, Estes M 3rd, Griffith JL, Steffens RA, et al. Interference with cardiac pacemakers by cellular telephones. N Engl J Med 1997;336:1473-9.  Back to cited text no. 13
Miller CS, Leonelli FM, Latham E. Selective interference with pacemaker activity by electrical dental devices. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;85:33-6.  Back to cited text no. 14
Rahn R, Zegelman M, Brief I, Kreuzer J, Frenkel G. Susceptibility of frequency adapted cardiac pacemakers to dental treatment. Dtsch Zahnarztl Z 1989;44:244-7.  Back to cited text no. 15
Luker J. The pacemaker patient in the dental surgery. J Dent 1982;10:326-32.  Back to cited text no. 16
Beach CW, Bramwell JD, Hutter JW. Use of an electronic apex locator on a cardiac pacemaker patient. J Endod 1996;22:182-4.  Back to cited text no. 17
Sowton E, Gray K, Preston T. Electrical interference in non-competitive pacemakers. Br Heart J 1970;32:626-32.  Back to cited text no. 18
Kaye GC, Butrous GS, Allen A, Meldrum SJ, Male JC, Camm AJ. The effect of 50 Hz external electrical interference on implanted cardiac pacemakers. Pacing Clin Electrophysiol 1988;11:999-1008.  Back to cited text no. 19
Woolley LH, Woodworth J, Dobbs JL. A preliminary evaluation of the effects of electrical pulp testers on dogs with artificial pacemakers. J Am Dent Assoc 1974;89:1099-101.  Back to cited text no. 20
Sidhu P, Shankargouda S, Dicksit DD, Mahdey HM, Muzaffar D, Arora S. Evaluation of interference of cellular phones on electronic apex locators: Anin vitro study. J Endod 2016;42:622-5.  Back to cited text no. 21
Gomez G, Duran-Sindreu F, Jara Clemente F, Garofalo RR, Garcia M, Bueno R, et al. The effects of six electronic apex locators on pacemaker function: Anin vitro study. Int Endod J 2013;46:399-405.  Back to cited text no. 22
van Lieshout EJ, van der Veer SN, Hensbroek R, Korevaar JC, Vroom MB, Schultz MJ. Interference by new-generation mobile phones on critical care medical equipment. Crit Care 2007;11:R98.  Back to cited text no. 23
Hietanen M, Sibakov V. Electromagnetic interference from GSM and TETRA phones with life-support medical devices. Ann Ist Super Sanita 2007;43:204-7.  Back to cited text no. 24


  [Figure 1], [Figure 2]

  [Table 1], [Table 2]


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