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Year : 2020  |  Volume : 23  |  Issue : 5  |  Page : 447-450
An in vitro study of comparative evaluation of efficacy of electrochemically activated water as a root canal irrigant in smear layer removal

Department of Conservative Dentistry and Endodontics, PMS College of Dental Science and Research, Thiruvananthapuram, Kerala, India

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Date of Submission22-Sep-2020
Date of Acceptance03-Nov-2020
Date of Web Publication10-Feb-2021


Aim: The aim was to compare and evaluate the efficacy of electrochemically activated water (ECA) against maleic acid, Mixture of tetracycline, acid and detergent. ie; 3% doxycycline, 4.25% citric acid, and 0.5% Tween 80 detergent (MTAD), Sodium hypochlorite (NaOCl), and saline as root canal irrigants in removing the smear layer.
Materials and Methods: Twenty single canal mandibular premolars were randomly divided into five groups (n = 4), decoronated, prepared to working length, and instrumented till F3 using protaper gold rotary files. Each group was assigned a different irrigant. Saline-negative control and NaOCl-positive control. Teeth were sectioned and subjected to Scanning Electron Microscopic analysis. ECA was prepared using a custom-made apparatus having two chambers of capacity 50 ml each separated by a polymer membrane. About 40 ml of tap water was collected in each chamber. Two graphite electrodes were connected to the top of the compartments, linked to a power supply which initiates electrolysis, and the solutions obtained in anodic and cathodic compartments were collected. Statistical analysis was done using one-way ANOVA and Post hoc Tukey analysis.
Results: NaOCl, maleic acid, and ECA had similar smear layer removal efficacy. MTAD was less efficient than the other irrigants tested. Saline did not remove the smear layer.
Conclusion: Electrochemically activated water has promising smear layer removal efficacy and is comparable with conventional root canal irrigants.

Keywords: Anolyte; catholyte; electrochemically activated water; smear layer

How to cite this article:
Mahesh M, Pillai R, Varghese N O, Salim AA, Murali N, Nair SS. An in vitro study of comparative evaluation of efficacy of electrochemically activated water as a root canal irrigant in smear layer removal. J Conserv Dent 2020;23:447-50

How to cite this URL:
Mahesh M, Pillai R, Varghese N O, Salim AA, Murali N, Nair SS. An in vitro study of comparative evaluation of efficacy of electrochemically activated water as a root canal irrigant in smear layer removal. J Conserv Dent [serial online] 2020 [cited 2023 Dec 8];23:447-50. Available from:

   Introduction Top

Endodontic treatment should focus not only on the eviction of pulp remnants and the widening of the root canal but also on smear layer removal.[1] Ostavik and Haapasalo denoted the importance of the removal of the smear layer and the presence of patent dentinal tubules in dwindling the time required to achieve disinfection.[2] Bystrom and Sundqvst also have shown that the presence of smear layer can inhibit or significantly delay the penetration of antimicrobial agents, such as intracanal irrigants and medicaments into the dentinal tubules.[3] Sodium hypochlorite is capaciously recommended and is now the preferred irrigant in root canal treatment because of its microbiocidal and organic tissue disbanding ability.[4] However, NaOCl does not effectively remove the smear layer and many in vitro and in vivo studies have reported moderate to severe cytotoxicity when sodium hypochlorite solution in clinically recommended concentrations is extruded through the apex.[5] Clearly, because of the potential toxicity of NaOCl, the investigation of alternative irrigants are important. Maleic acid is a mild organic acid that removes the smear layer effectively at concentrations of 5% and 7%.[6] MTAD is a new irrigating solution containing a mixture of a tetracycline isomer, an acid, and a detergent developed by Torabinejad et al.

Electrochemical activation occurs in the electrolysis cell, consisting of a cathode and an anode segregated by a semi-permeable membrane which separates water to the alkaline fraction – catholyte and acidic fraction – the anolyte.[7] When electric current is passed, a series of redox reactions occur on the surface of the cathode and anode. As a result, new elements are formed, and the composition and structure of water are also changed. Electrochemical treatment in the anode and cathode chambers results in the synthesis of two types of solutions. The resultant at anode chamber is termed as anolyte and cathode chamber as catholyte. The anolyte solution has been termed as super-oxidized water or oxidative potential water.[8] The pH of anolyte may be acidic (anolyte), neutral (anolyte neutral) or alkaline (Anolyte Neutral Cathodic [ANC]). Acidic anolyte was used initially but presently neutral and alkaline solutions have been recommended for clinical applications. Anolyte neutral is produced in the anode chamber, pH = 6.0 ± 1.0. The main biocidal reagents are HOCl, ClO, ClO, and H2O2. The microbiocidal potential of anolyte is provided by the presence of active chlorine, a strong oxidizing agent. ANC is produced at anode chamber, partially mixed with OH that is transferred through the membrane in the cathode chamber. pH = 7.7 ± 0.5. The main biocidal reagents are HOCl, ClO, HO2, and O2. In comparison to anolyte neutral, the ANC solution contains a higher concentration of peroxides and demonstrates an increased antiseptic effect at lower concentrations of active chlorine and increased cleaning ability.[9] Catholyte is an alkaline solution with oxidation-reduction potential. It is characterized by a pH value >9. The main reagents are OH, H2O2, and NaOH and provide a strong cleaning or detergent effect of catholyte. It dissolves necrotic tissue being safe for vital tissues.[10] The objective of this study was to juxtapose and compute the efficacy of electrochemically activated water (ECA) against maleic acid, MTAD, NaOCl, and saline as root canal irrigants in removing the smear layer.

   Materials and Methods Top

Twenty single-rooted, mandibular premolars were used in this study. Teeth extracted for therapeutic reasons and which were devoid of any developmental defects, caries, and regressive changes were included. The samples were decoronated with a diamond disk. Working length was standardized at 15 mm using a 15 K file. Teeth were then categorized into 5 groups based on the irrigants used as follows:

  • Group I-NaOCl 3%
  • Group II-maleic acid 7%
  • Group III-ECA
  • Group IV-MTAD
  • Group V-saline.

The ECA solution was prepared using a custom-made apparatus which was made of two chambers capable of storing 50 ml of the solution, separated by a polymer membrane. Connected to the top of the compartments were two graphite electrodes, 7 cm long and 1 cm in diameter, connected to a power supply that can deliver a maximum of 12.5 Volt and 3.5 Amp [Figure 1]. 40 ml of tap water was poured into each compartment which initiated electrolysis of water. The solution obtained in anodic and cathodic compartments were collected. The shelf life of purely extracted ECA water was 10 min. Numerous studies from Russia have proved that after the first 15 min, it loses 70% potency. Hence it was used as soon as it was generated.
Figure 1: Electrochemically activated water apparatus

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Other irrigants used include maleic acid 7% and MTAD (3% doxycycline, 4.25% citric acid, and 0.5% Tween 80 detergent). Sodium hypochlorite was taken as positive control and saline as negative control. Each canal was instrumented up to No. 25 K file followed by rotary instrumentation using protaper gold rotary files up to size F3. Apical instrumentation to a 30 size Ni-Ti file with 0.06 coronal taper was effective in the removal of debris and smear layer from apical 1/3rd of the pulp space. Each irrigant was delivered through a Max-I-Probe (Dentsply Maillefer) 28 gauge placed 2 mm short of working length. In each group, a high volume flush with 10 ml of irrigant was carried out following coronal flaring with Gates Glidden burs. Irrigation with 1 ml was performed for at least 10 s after every file. Following preparation, a final flush with 10 ml was carried out for a minimum of 60 s. Irrigants were allowed to come in contact with canal dentin for 5–7 min and gently agitated using No. 20 K file with a carting motion, 2 mm short of working length. The samples were longitudinally sectioned and subjected to Scanning electron microscopy. Diamond discs were used to cut deep grooves on buccal and lingual surfaces of roots, without perforating the inner curvatures. The roots were separated using chisel and mallet; one half of each tooth is designated and assembled for SEM examination.

The specimens were dehydrated by ethyl alcohol and mounted on coded stubs, air dried, placed in a vacuum chamber, and sputter coated with gold. The dentinal surfaces were observed at coronal, middle, and apical thirds with a magnification of ×4000 for the presence or absence of smear layer and visualization of the dentinal tubules orifice. Photomicrographs (×4000) of the coronal, middle, and apical thirds were taken.

The scores were attributed according to the rating system developed by Torabinejad et al.

  1. No smear layer (no smear layer on the surface of the root canal. All tubules were clean and open)
  2. Moderate smear layer (no smear layer on the surface of the root canal, but tubules contained debris)
  3. Heavy smear layer (smear layer covered the root canal surface and the tubules).

Statistical analysis was done using one-way ANOVA and Post hoc Tukey analysis [Table 1], [Figure 2], and performed with the help of SPSS IBM 22 version IBM- Integrated Business Machine, IBM SPSS Statistics, Norman H Nile, Incorporated in Deleware, Chicago, USA.
Table 1: One way-ANOVA and post hoc Tukey analysis of Irrigant groups

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Figure 2: Graph showing the comparison of groups

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   Results Top

Sodium hypochlorite effectively removed the smear layer in all 3 regions i.e., coronal, middle, and apical thirds. Maleic acid was similar to NaOCl and more effective in the middle third. ECA was more effective in coronal and apical regions, even though minute amounts of smear layer were scattered over the tubule orifices in the middle 1/3rd. MTAD was less efficient when compared to other irrigants and exuberant areas of smear layer were seen covering tubule orifices as well as peritubular dentin, particularly in the apical region. Saline was the least effective and it failed to remove the smear layer from any region.

   Discussion Top

In the current study, a thin smooth and uniform smear layer was seen in morsel in the first 3 groups, and a dense irregular smear layer blocking the tubule openings was seen in the last 2 groups. Kennedy et al. denoted that the smear layer's presence plays a significant role in an increase or decrease in apical leakage. Its absence makes the dentin more conducive for a better and closer adaptation of the gutta percha to the canal walls.[11]

Maleic acid when used at a concentration of higher than 7% induced damage to the intertubular dentin[12] and consequently in the at hand study, 7% concentration was used and found effectual in removing the smear layer. It has been reported to remove the smear layer present in cavities prepared for adhesive dentistry. The smear layer present in adhesive dentistry can be quite contrasting, from the endodontic smear layer. In the former, the tooth may be vital and the dentinal tubules hold odontoblastic processes and dentinal fluid, whereas in the later, the tooth is nonvital and devoid of dentinal fluid or odontoblastic processes. Smear layer unfastening ability of maleic acid was less in vital teeth, probably due to the presence of the dentinal fluid which can exert pressure and so affect its complete removal. The smear layer detaching ability of maleic acid in the present study is in agreement with Erickson and Van Meerbeek et al. who proclaimed that the smear layer was removed in adhesive dentistry using a self-etching primer and differs with Jordon et al. who reported that it only alters the smear layer.[13],[14],[15]

Both ECA and NaOCl left a thinner smear layer with a smoother and more even surface. The texture of treated canal surfaces was relatively uniform in the various regions of the canal for both. NaOCl resulted in open tubules predominantly in the coronal and middle thirds of root canals and was less effective in the apical third whereas ECA resulted in more numerous open dentinal tubules in the apical and coronal regions. The results suggest that irrigation with electrochemically activated solutions provide efficient cleaning of root canal walls and may be an alternative to NaOCl in conventional root canal treatment. However, further investigations of ECA solutions are warranted.

MTAD was efficient in removing the smear layer mainly from the middle third. Its action in apical third was, however, very much impaired. This is in agreement with Ciucchi et al. who stated that there was a definite decline in the efficiency of irrigating solution along the apical part of the canals.[16] This can probably be elucidated by the fact that dentin in the apical third is much more sclerosed and the number of dentinal tubules present there is less. Torabinejad et al. unveiled that the effectiveness of MTAD to completely remove the smear layer is enhanced when low concentrations of NaOCl are used as an intracanal irrigant before the use of MTAD as a final rinse. This combination and sequence do not seem to modulate the structure of the dentinal tubules.[17] In this study, MTAD was used as a sole irrigant in group IV, without the prior usage of NaOCl. This might be the reason for its poor effectiveness in smear layer removal in the current study. Saline did not remove the smear layer in any levels of the root canal and in effect had only a flushing property.

The present study was done in vitro, so the results obtained do not necessarily concede any definite actions of the tested irrigants in situ. Blood, tissue remnants, and a multitude of other variables may affect the actions of agents under investigation in the pulp space. Curved canals can be more challenging and make the effective cleaning of the root canal system onerous. Profound penetration of the irrigation needle takes place in single-rooted premolar tooth because of wider canals. Therefore, results may vary in posterior teeth with circumscribed canals. Nevertheless, further long-term clinical studies are necessary to confirm these results and evaluate their relevance to treatment outcome.

   Conclusion Top

ECA was found to have auspicious smear layer removal efficacy among the 5 groups when used individually. It was highly effective when used in the first 10 min after generation, similar to NaOCl and maleic acid. MTAD was less efficient than the other irrigants tested. Saline did not remove the smear layer and had only a mere cleansing effect.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Paul ML, Mazumdar D, Niyogi A, Baranwal AK. Comparative evaluation of the efficacy of different irrigants including MTAD under SEM. J Conserv Dent 2013;16:336-41.  Back to cited text no. 1
[PUBMED]  [Full text]  
Orstavik D, Haapasalo M. Disinfection by endodontic irrigants and dressings of experimentally infected dentinal tubules. Endod Dent Traumatol 1990;6:142-9.  Back to cited text no. 2
Bystrom A, Sundqvist G. The antibacterial action of sodium hypochlorite and EDTA in 60 cases of endodontic therapy. Int Endod J 1985;18:35-40.  Back to cited text no. 3
Qualtrough AJE, Whitworth JM, Dummer PM. Preclinical endodontology: An international comparison. Int Endod J 1999;32:406-14.  Back to cited text no. 4
Koulaouzidou EA, Margelos J, Beltes P, Kortsaris AH. Cytotoxic effects of different concentrations of neutral and alkaline EDTA solutions used as root canal irrigants. J Endod 1999;25:21-3.  Back to cited text no. 5
Kaushal R, Bansal R, Malhan S. A comparative evaluation of smear layer removal by using ethylenediamine tetraacetic acid, citric acid, and maleic acid as root canal irrigants: An in vitro scanning electron microscopic study. J Conserv Dent 2020;23:71-8.  Back to cited text no. 6
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Petrushanko IIu, Lobyshev VI. Nonequilibrium state of electrochemically activated water and its biological activity. Biofizika 2001;46:389-401.  Back to cited text no. 7
Hata G, Uemura M, Weine FS, Toda T. Removal of smear layer in the root canal using oxidative potential water. J Endod 1996;22:643-5.  Back to cited text no. 8
Bakhir VM, Grishin VP, Panicheva SA, Toloknov VI. Assessment of the effectiveness of medical instruments sterilized by electrochemically activated solutions and computer modeling of the dynamics of hospital infections. Medizinskaia Tekhnika 1999;2:14-6.  Back to cited text no. 9
Prilutskii VI, Bakhir VM. Electrochemically activated water: Anomalous properties, mechanism of biological action. M., All Russian Research and Test Institute of Medical Equipment, Moscow, Russia. 1997.  Back to cited text no. 10
Kennedy WA, Walker WA 3rd, Gough RW. Smear layer removal effects on apical leakage. J Endod 1986;12:21-7.  Back to cited text no. 11
Prabhu SG, Rahim N, Bhat KS. Comparison of removal of endodontic smear layer using sodium hypochlorite, EDTA and different concentrations of maleic acid: A SEM study. Endodontology 2003;15:20-5.  Back to cited text no. 12
Erickson RL. Surface interactions of dentin adhesive materials, Oper Dent 1992;5:81-94.  Back to cited text no. 13
Van Meerbeek B, Lambrechts P, Inokoshi S, Braem M, Vanherle G. Factors affecting adhesion to mineralized tissues. Oper Dent 1992;Suppl 5:111-24.  Back to cited text no. 14
Jordan RE. Adhesives in dentistry: Clinical considerations. Oper Dent 1992;5:95-102.  Back to cited text no. 15
Ciucchi B, Khettabi M, Holz J. The effectiveness of different endodontic irrigation procedures on the removal of the smear layer: A SEM study. Int Endod J 1989;22:21-8.  Back to cited text no. 16
Torabinejad M, Cho Y, Khademi AA, Bakland LK, Shabahang S. The effect of various concentrations of sodium hypochlorite on the ability of MTAD to remove the smear layer. J Endod 2003;29:233-9.  Back to cited text no. 17

Correspondence Address:
Dr. M Mahesh
Department of Conservative Dentistry and Endodontics, PMS College of Dental Science and Research, Golden Hills, Vattapara, Venkode, Thiruvananthapuram - 695 028, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/JCD.JCD_488_20

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