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ORIGINAL ARTICLE
Year : 2010  |  Volume : 2  |  Issue : 3  |  Page : 113-118

The effect of 17% EDTA and MTAD on smear layer removal and on erosion of root canal dentin when used as final rinse: An in vitro SEM study


1 Department of Conservative Dentistry and Endodontics, YCMM and RDF's Dental College, Ahmednagar, Maharashtra, India
2 Department of Conservative Dentistry and Endodontics, CSMSS Dental College, Aurangabad, Maharashtra, India
3 Department of Prosthodontics, CSMSS Dental College, Aurangabad, Maharashtra, India

Date of Web Publication21-Apr-2012

Correspondence Address:
Vishal A Mahajan
Department of Conservative Dentistry and Endodontics, Y.C.M.M. and RDF's Dental College, Vadagaon Gupta, Tal. and Dist. Ahmednagar, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2231-0754.95282

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   Abstract 

Background: The aim of the present study was to evaluate and compare the ability of a mixture of tetracycline isomer, citric acid and detergent (MTAD) and ethylene diamine tetra-acetic acid (EDTA) in removing the smear layer along with their effects on peritubular and intertubular dentinal structures by scanning electron microscopic (SEM) examination. Materials and Methods: Thirty recently extracted maxillary and mandibular single-rooted human teeth were divided into 3 groups and prepared to an apical size of 30. In Group 1, 2, and 3, MTAD, EDTA, and distilled water were used, respectively, as a final rinse solution to remove the smear layer. The specimens were subjected to SEM evaluation for the presence or absence of the smear layer and degree of erosion using a scoring system. Results: The result showed that MTAD shows better smear layer removing ability and does not significantly change the structure of dentinal tubules. Conclusion: MTAD is an efficient solution for the removal of the smear layer, especially in the apical third of root canals, and does not significantly change the structure of the dentinal tubules.

Keywords: Ethylene diamine tetra-acetic acid, erosion of dentinal tubules, MTAD, smear layer removal


How to cite this article:
Mahajan VA, Kamra AI, Dahiwale SS. The effect of 17% EDTA and MTAD on smear layer removal and on erosion of root canal dentin when used as final rinse: An in vitro SEM study. J Int Clin Dent Res Organ 2010;2:113-8

How to cite this URL:
Mahajan VA, Kamra AI, Dahiwale SS. The effect of 17% EDTA and MTAD on smear layer removal and on erosion of root canal dentin when used as final rinse: An in vitro SEM study. J Int Clin Dent Res Organ [serial online] 2010 [cited 2018 Dec 17];2:113-8. Available from: http://www.jicdro.org/text.asp?2010/2/3/113/95282


   Introduction Top


It has been recognized for many years that root canal instrumentation produces a smear layer that covers the surfaces of root canal walls. [1],[2],[3] The smear layer consists of inorganic and organic substances and has 2 layers, the superficial smear layer of 1-2 μm thickness, and the deeper smear plug having thickness up to 40 μm. [1],[2],[3],[4],[5],[6]

The removal of smear layer is necessary to achieve disinfection of the root canal system by deeper penetration of the root canal medicaments and irrigants. It also allows greater penetration of the root canal sealers into the dentinal tubule openings, aiding an intimate adaptation of the obturating materials with the prepared canal walls. [1],[2],[3],[6],[7],[8],[9],[10]

Various agents including organic acids, chelating agents, ultrasonics, and lasers have been used to remove the smear layer. Of these, the chelating agent ethylene diamine tetra-acetic acid (EDTA) in its different physical forms and formulations is most commonly used for smear layer removal; [11] however, the search continues for newer and better agents. Recently, a new irrigating solution containing a mixture of tetracycline isomer, citric acid, and detergent (MTAD) has been introduced as a final rinse solution for removing the smear layer from the surface of the root canal. [12]

The aim of the present study was to confirm and compare the ability of MTAD and aqueous ethylene diamine tetra-acetic acid (EDTA) to remove the smear layer. In addition, their effects on peritubular and intertubular dentinal structures were examined by scanning electron microscopy (SEM).


   Materials and Methods Top


Thirty recently extracted maxillary and mandibular single-rooted human teeth with relatively straight roots were used in this study.

The coronal part of the teeth was disked away using a diamond disk at the level of the cementoenamel junction, and the patency of the canals was verified. The external surface of each root was grooved longitudinally on the mesial and distal side using a diamond disk. A #15 file was passed through the apical foramen until its tip became visible. This distance minus 1 mm was taken. A small piece of softened wax was placed at the apex of each tooth to simulate natural apical counter pressure and to prevent any flow of irrigants. [10]

All teeth were randomly divided into 3 groups containing 10 teeth each.

Group 1: MTAD

In this group, normal saline and 1.3% sodium hypochlorite were used alternately as irrigants during instrumentation. MTAD was used as the final rinse per the manufacturer's instructions. (Biopure MTAD; Dentsply Tulsa Dental, OK, USA)

Group 2: Ethylene diamine tetra-acetic acid

In this group, normal saline and 1.3% sodium hypochlorite were used alternately as irrigants during instrumentation. A 17% aqueous solution of EDTA was used as the final rinse per the manufacturer's instructions (Dent Wash-Prime Dental, India) followed by 1.3% sodium hypochlorite.

Group 3: Distilled water

In this group, distilled water was used as an irrigant during instrumentation and as the final rinse. This group served as the positive control.

All teeth were prepared by RaCe 0.04 instrument system (FKG Dentaire, Switzerland) to an apical size of 30. A total of 10 mL of irrigants was used in each root canal. The irrigants were delivered using 28-gauge, side-vented ProRinse needles that penetrated to within 1-2 mm from the working length in each canal. The instrumentation time for each canal was approximately 15-20 min. After instrumentation, all canals were dried with sterile paper points. Later, each dried specimen was split into 2 with chisel and mallet along the prepared groove. A half of each specimen was discarded; the other half was prepared for scanning electron microscopic (SEM) examination. [13],[14]

Scoring of the presence and absence of smear layer on the surface of the root canal wall or in the dentinal tubules at the coronal, middle, and apical portions of each canal was done per the following criteria: [12]

  1. No smear layer. No smear layer on the surface of the root canals: 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.
In addition, the investigators scored the degree of erosion of dentinal tubules according to the following criteria: [12]

  1. No erosion. All tubules looked normal in appearance and size.
  2. Moderate erosion. The peritubular dentin was eroded.
  3. Severe erosion. The intertubular dentin was destroyed, and tubules were connected with each other.
The data was then subjected to statistical analysis using Fisher's Exact Test and Likelihood Ratio.


   Results Top


The samples in Group 1 (MTAD) showed complete removal of the smear layer in 90% of specimens in the coronal and middle areas, and 100% of specimens in the apical area. Partial removal of the smear layer was noted in the remaining specimens in both coronal and middle portions [Figure 1]a-c.
Figure 1: (a) MTAD coronal third; (b) MTAD middle third; (c) MTAD apical third

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The specimens in Group 2 (EDTA) showed complete removal of the smear layer in 80% of samples in both coronal and middle areas, and 50% of specimens in the apical area. Partial removal of the smear layer was noted in the remaining specimens in coronal, middle, and apical areas [Figure 2]a-c. None of the samples in groups 1 and 2 showed the presence of a heavy smear layer.
Figure 2: (a) EDTA coronal third; (b) EDTA middle third; (c) EDTA apical third

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Distilled water in Group 3 samples was unable to remove the smear layer. A heavy smear layer was noted in all the specimens in this group [Figure 3]a-c.
Figure 3: (a) Distilled water coronal third; (b) distilled water middle third; (c) distilled water apical third

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When evaluating the degree of erosion, no erosion was noted in all the specimens in the coronal and middle areas of samples treated with MTAD. In apical areas, only 10% of specimens treated with MTAD showed some erosion, whereas the remaining specimens were normal [Figure 1]a-c.

In samples treated with EDTA, normal tubules were noted in 50% of specimens in both coronal and middle areas, and 80% of specimens in the apical areas. Moderate erosion was noted in 20% of specimens in coronal and apical areas, and 50% of specimens in the middle area. A severe degree of erosion was noted in 30% of specimens in the coronal area of samples treated with EDTA [Figure 2]a-c.

No statistically significant difference was found between MTAD and EDTA groups when the ability of these 2 solutions was compared in the coronal and middle areas of the specimens (P = 1.000). In the apical area, a statistically significant difference was found between MTAD and EDTA groups (P = 0.033).

A statistically significant difference was found between MTAD and EDTA groups when the degree of erosion in the coronal and middle areas was compared (P = 0.013 and 0.033, respectively). No statistically significant difference was found between MTAD and EDTA groups in the apical area (P = 1.000) when the degrees of erosion were compared.


   Discussion Top


The present study was carried out to compare the ability of MTAD and EDTA to remove the smear layer, as well as to examine their effects on peritubular and intertubular dentinal structure with an SEM.

Results of the present study showed that in Group 1, where a combination of NaOCl and MTAD was used, most root surfaces in coronal, middle, and apical thirds had no smear layer. The coronal and middle third areas showed a complete smear layer removal in 9 out of 10 specimens. A moderate smear layer was seen in one specimen. The apical third showed complete smear removal in all the specimens. These findings are in agreement with a study conducted by Torabinejad et al. In that study, of 10 samples irrigated with 1.3% NaOCl and MTAD, 27 out of 30 root canal surfaces exhibited complete smear layer removal. A moderate smear layer was observed in these regions for the remaining samples. [15] Our results are also in agreement with another study by Torabinejad et al, in which the surfaces of root canals and dentinal tubules in the coronal, middle, and apical thirds of all 12 samples tested were found to be free from debris. [12] In Group 2, where a combination of NaOCl and 17% EDTA was used, coronal and middle third areas showed complete smear layer removal in 8 out of 10 specimens (80%). A moderate smear layer was observed in these regions for the remaining specimens. Five out of 10 specimens (50%) in the apical third showed a complete smear layer removal. Results of the present study are in agreement with an unpublished study by Shaligram. [16] He used liquid EDTA for smear layer removal in his study carried out at Government Dental College and Hospital, Aurangabad and found complete smear removal in 96% of specimens in the coronal third, 74% of specimens in the middle third and 55% of specimens in the apical third. Our findings also corroborate the findings of Torabinejad et al, which noted no smear layer in 70% of root surfaces in coronal and middle thirds. [15] A moderate smear layer was observed on 80% of surfaces in the apical third with 20% of surfaces showing complete smear removal.

The smear layer removal action of EDTA can be attributed to its chelation action on the root canal. The moderate smear removal observed in the apical third may be due to incomplete penetration of EDTA in the apical area of the root canal.

On comparison of smear layer removal in the coronal area and middle third areas of the MTAD group (Group 1) and EDTA group (Group 2), no statistically significant difference was found. In the apical area, however, a statistically significant difference was noted between the 2 groups, with EDTA group showing less removal of smear layer. These results are in agreement with those of Torabinejad et al, which showed more effective removal of smear layer by MTAD as compared with EDTA in the apical area. [12] This could be attributed to the anatomy and lack of penetration of irrigants in the apical portion of the canals. [17] In this respect, we found that MTAD performs better than EDTA. This may also be attributed to the synergistic action of citric acid, doxycycline, and detergent present in MTAD. [7],[12],[15],[18] On evaluation of the degree of erosion it was noted that in the MTAD group, normal tubules with no erosion were seen in all the specimens in coronal and middle areas. In apical areas, tubules with erosion were seen in one specimen, whereas the remaining specimens showed no erosion of tubules. These findings are similar to those of Torabinejad et al, which demonstrated that use of MTAD did not change the structure of dentinal tubules in all but one specimen. [12]

In the EDTA group, normal tubules (no erosion) were noted in 5 specimens in both coronal and middle areas, and 8 specimens in apical areas. A moderate degree of erosion was noted in 2 specimens in coronal and apical areas, and 5 specimens in the middle area. A severe degree of erosion was noted in 3 specimens in the coronal area.

When comparing the degree of erosion in coronal and middle third areas of the MTAD and EDTA groups, a statistically significant difference was found, with the MTAD group showing no erosion. Erosion of dentinal tubules seen in the EDTA group may be due to the hyperdecalcification induced by EDTA on dentin. [19],[20]

No statistically significant difference in erosion was found between the 2 groups in the apical area. This may be due to the inadequate penetration of EDTA in the apical third and incomplete smear layer removal in that region. Results of the present study are in agreement with studies conducted by Baumgartner et al, [8] Calt and Sarper, [19] Niu et al, [20] and Torabinejad et al, [12] all of which have demonstrated erosive effects of EDTA on dentinal tubular structure. Based on the results of this study, it appears that MTAD does not significantly change the structure of the dentinal tubules. This may be due to a lower concentration (4.25%) of citric acid present in MTAD. This is consistent with the results of a study by Haznedaroqlu, which found no erosion when lower concentrations (5%-10%) of citric acid were used, whereas 25% and 50% concentrations resulted in the destruction of dentinal tubules. [18] Erosion of the dentinal tubules may cause an increase in coronal microleakage in EDTA-treated specimens [21] and can affect the flexural strength and modulus of elasticity of dentin if prolonged exposure to EDTA occurs. [22]

Based on our findings it appears that MTAD is an efficient solution for the removal of the smear layer, especially in the apical third of root canals, and does not significantly change the structure of the dentinal tubules.

 
   References Top

1.Czonstkowsky M, Edmund G, Wilson Holstein FA. The smear layer in endodontics. Dent Clin North Am 1990;34:13-25.   Back to cited text no. 1
    
2.Sen BH, Wesselink PR, Turkun M. The smear layer: A phenomenon in root canal therapy. Int Endod J 1995;28:141-8.  Back to cited text no. 2
    
3.Torabinejad M, Handysides R, Khademi A, Bakland LK. Clinical implications of the smear layer in endodontics: A review. Oral Surg Oral Med Oral Path Oral Radiol Endod 2002;94:658-66.  Back to cited text no. 3
    
4.Aktener BO, Cengiz T, Piskin B. The penetration of smear layer into dentinal tubules during instrumentation with surface active reagents: A scanning electron microscopic study. J Endod 1989;15:588-90.  Back to cited text no. 4
    
5.Gutiérrez JH, Herrera VR, Berg EH, Villena F, Jofré A. The risk of intentional dissolution of the smear layer after mechanical preparation of root canals. Oral Surg Oral Med Oral Pathol 1990;70:96-108.   Back to cited text no. 5
    
6.Mader CL, Baumgartner JC, Peters DD. Scanning electron microscopic investigation of the smeared layer on root canal walls. J Endod 1984;10:477-83.  Back to cited text no. 6
    
7.Barkhordar RA, Watanabe LG, Marshall GW, Hussain MZ. Removal of intracanal smear by doxycycline in vitro. Oral Surg Oral Med Oral Pathol and Endod 1997;84:420-3.  Back to cited text no. 7
    
8.Baumgartner C, Mader C. A scanning electron microscopic evaluation of four root canal irrigation regimens. J Endod 1987;13:147-57.  Back to cited text no. 8
    
9.Berg MS, Jacobsen EL, BeGole EA, Remeikis NA. A comparison of five irrigating solutions: A scanning electron microscopic study. J Endod 1986;12:192-7.  Back to cited text no. 9
    
10.Ciucchi B, Khettabi M. The effectiveness of different endodontic irrigation procedures on the removal of the smear layer: A scanning electron microscopic study. Int Endod J 1989;22:21-8.  Back to cited text no. 10
    
11.Hülsmann M, Heckendorff M, Lennon A. Chelating agents in the root canal treatment: Mode of action and indications for their use. Int Endod J 2003;36:810-30.   Back to cited text no. 11
    
12.Torabinejad M, Khademi AA, Babagoli J, Cho Y, Johnson WB, Bozhilov K, et al. A New Solution for the Removal of the Smear Layer. J Endod 2003;29:170-5.  Back to cited text no. 12
    
13.Aktener BO, Bilkay U. Smear layer removal with different concentration of EDTA- Ethylenediamine mixtures. J Endod 1993;19:228-31.  Back to cited text no. 13
    
14.Cengiz T, Aktener BO, Piskin B. The effect of dentinal tubule orientation on the removal of smear layer by root canal irrigants. A scanning electron microscopic study. Int Endod J 1990;23:163-71.  Back to cited text no. 14
    
15.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. 15
    
16.Shaligram A. Comparative in vitro evaluation of commercially available liquid and cream preparation of EDTA in removing smear layer from prepared root canal walls. An SEM study. MDS Thesis. Aurangabad, India: B.A.M. University; 2003.   Back to cited text no. 16
    
17.Garberoglio R, Becce C. Smear layer removal by root canal irrigants. Oral Surg Oral Med Oral Pathol 1994;78:359-67.  Back to cited text no. 17
    
18.Haznedaroglu F. Efficacy of various concentrations of citric acid at different pH values for smear layer removal Oral Surg Oral Med Oral Pathol and Endod 2003;96:340-4.  Back to cited text no. 18
    
19.Calt S, Serper A. Time-dependent effects of EDTA on dentin structures. J Endod 2002;28:17-9.  Back to cited text no. 19
    
20.Niu W, Yoshioka T, Kobayashi C, Suda H. A Scanning electron microscopy study of dentinal erosion by final irrigation with EDTA and NaOCl solutions. Int Endod J 2002;35:934-9.  Back to cited text no. 20
    
21.Park DS, Torabinejad M., Shabahang S. The effect of MTAD on the coronal leakage of obturated root canals. J Endod 2004;30:890-2.  Back to cited text no. 21
    
22.Machnick T, Torabinejad M, Munoz C, Shabahang S. Effect of MTAD on Flexural Strength and Modulus of Elasticity of Dentin. J Endod 2003;29:747-50.  Back to cited text no. 22
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]


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