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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 8  |  Issue : 1  |  Page : 16-19

Comparative evaluation of the cleaning efficacy of two commercially available buffered sodium hypochlorite solutions by measurement of lateral penetration of sealer into radicular dentin: A fluorescence microscopic study


Department of Conservative Dentistry and Endodontics, Dr. DY Patil Dental College and Hospital, Pune, Maharashtra, India

Date of Submission01-Jul-2020
Date of Decision09-Jul-2020
Date of Acceptance04-Sep-2021
Date of Web Publication25-Feb-2021

Correspondence Address:
Shalini D Aggarwal
Department of Conservative Dentistry and Endodontics, Dr. DY Patil Dental College and Hospital, Sant Tukaram Nagar, Pimpri, Pune - 411 018, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jdrr.jdrr_71_20

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  Abstract 


Aim: The aim of this study was to assess and compare the efficacy of two commercially available sodium hypochlorite (NaOCl) solutions by measurement of lateral penetration of sealer into radicular dentin using fluorescence microscopy – an in vitro study. Materials and Methods: Thirty-six roots were obtained and stored in 0.5% thymol solution. Roots were then randomly allocated to the respective groups – Group I (control group): roots irrigated with 3% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA) solution (n = 12), Group II: roots irrigated with chloraxid extra (solution of 5.25% NaOCl with surfactants) with n = 12, and Group III: roots irrigated with ChlorOQuick (solution of 5% NaOCl with 9% etidronic acid solution) with n = 12. Root canal preparation was done, and samples were obturated using AH plus sealer mixed with rhodamine dye. Slices of 0.5 mm thickness were mounted on glass slides and examined with fluorescence microscope. Statistical Analysis Used: Student's unpaired t-test and one-way analysis of variance with Tukey-Kramer multiple comparison test were used for statistical analysis. Results: There was no significant difference between mean values of measurement of lateral penetration of sealer into radicular dentin when Group I, Group II and in Group III compared each other (P = 0.3598). Group I (control group – 3% NaOCl followed by 17% EDTA) permitted the maximum amount of sealer penetration laterally into the dentinal tubules from the root canal lumen followed by Group II (5.25% NaOCl modified with surfactants). Group III (5% NaOCl + 9% etidronic acid) showed the least sealer penetration in this study. Conclusions: Within the limitations of this study, we could conclude that the cleaning efficacy of modifications to NaOCl provided results similar to the conventional irrigation protocol and hence could be used as a stand-alone irrigant.

Keywords: Etidronic acid, root canal dentin, sealer penetration, sodium hypochlorite, surfactants


How to cite this article:
Kurtarkar P, Aggarwal SD, Digholkar R, Dhatavkar P. Comparative evaluation of the cleaning efficacy of two commercially available buffered sodium hypochlorite solutions by measurement of lateral penetration of sealer into radicular dentin: A fluorescence microscopic study. J Dent Res Rev 2021;8:16-9

How to cite this URL:
Kurtarkar P, Aggarwal SD, Digholkar R, Dhatavkar P. Comparative evaluation of the cleaning efficacy of two commercially available buffered sodium hypochlorite solutions by measurement of lateral penetration of sealer into radicular dentin: A fluorescence microscopic study. J Dent Res Rev [serial online] 2021 [cited 2021 Apr 21];8:16-9. Available from: https://www.jdrr.org/text.asp?2021/8/1/16/310192




  Introduction Top


The success of root canal treatment depends on effective cleaning and shaping of the root canals to get rid of the pulpal tissue, dentinal debris, and the microorganisms. Irrigants play a pivotal part in thorough debridement of the root canal and thus render complete disinfection of the canal system by cleaning all the canal irregularities such as fins which are not possible to be cleaned mechanically.

Sodium hypochlorite (NaOCl) still remains the cornerstone of disinfection and cleansing of the root canal system. In spite of its flaws such as tissue destruction and its inability to remove the debris created after tissue dissolution, NaOCl still remains the irrigant of choice due to its potent antimicrobial and excellent tissue dissolution property.

Cleaning efficacy of NaOCl is mainly dependent on three parameters:

  1. pH
  2. Concentration
  3. Time.


Higher concentrations and increased exposure time to NaOCl lead to increased amounts of tissue dissolution.[1]

When modifiers are added to NaOCl, in the form of surfactants, the surface tension of the resulting solution is reduced which results in improved cleaning of the root canal walls, removal of the smear layer, better penetration of the irrigants into the dentinal tubules, and increased pulp dissolution.[2]

Another desirable addition to NaOCl is etidronic acid (HEBP) which is a chelator. Even upon being mixed, NaOCl and HEBP retain their properties individually and the resultant solution leads to better debris removal. The use of a combination of NaOCl and HEBP prevents smear layer formation and may thus render a final rinse with ethylenediaminetetraacetic acid (EDTA) nonessential.

The aim and objectives of this study were to assess and compare the efficacy of two commercially available NaOCl solutions by measurement of lateral penetration of sealer into radicular dentin using fluorescence microscopy – an in vitro study.


  Materials and Methods Top


Extracted teeth were processed and then decoronated at the crown–root junction, followed by storing the roots in a 0.5% thymol solution. Intact roots of human teeth with single canals were included in the study. Grossly decayed teeth and roots with developmental defects, with cracks, and with calcified canals were excluded in this study.

Roots were then randomly allocated to the respective groups. Chemomechanical preparation was performed, followed by the use of Gates Glidden drill (MANI, INC) of size 2–3 for the enlargement of the coronal third of the roots. Working length determination was done for each root using #10 K-File (Dentsply Maillefer), and root canal preparation was done using ProTaper instruments (Dentsply Maillefer) till apical size 20 (F1).

Irrigation was performed after each instrument change using the following solutions:

Group I (control group): roots irrigated with 3% NaOCl and 17% EDTA solution (n = 12), Group II: roots irrigated with chloraxid extra (solution of 5.25% NaOCl with surfactants) with n = 12, and Group III: roots irrigated with ChlorOQuick (solution of 5% NaOCl with 9% etidronic acid solution) with n = 12.

All irrigating solutions were then introduced in the root canal with the help of a 2-ml plastic syringe (Dispo Van) with a side-vented needle (Septodont) of 30 gauge inserted to a depth that was approximately 2–3 mm short of the working length.

Roots canals were then dried with paper points (Sure Dent Corporation, Korea). For fluorescence microscopy, the sealer was manipulated with 0.5% rhodamine B fluorescent dye (by Sigma-Aldrich). All canals were then obturated with a resin-based sealer using a lentulospiral (Dentsply).

Each root was cut perpendicular to its long axis using a 0.3-mm microtome saw of slow speed to obtain sections 3–4 mm in thickness which were polished using a Combination Stone (Carborundum Universal Limited) to a thickness of 0.5 mm. The samples obtained were further mounted on glass slides and were examined with fluorescence microscope (Leica DFC420).

Statistical analysis used

Student's unpaired t-test and one-way analysis of variance (ANOVA) with Tukey-Kramer multiple comparison test were used for statistical analysis.


  Results Top


[Table 1] depicts a comparison of mean values of measurement of lateral penetration of sealer into radicular dentin in Group I, Group II, and Group III.
Table 1: Comparison of mean values of measurement of lateral penetration of sealer into radicular dentin in Group I, Group II, and Group III

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From the data obtained from [Table 1], Group II (5.25% NaOCl modified with surfactants) permitted the maximum amount of sealer penetration laterally into the dentinal tubules from the root canal lumen followed by Group I (control group – 3% NaOCl followed by 17% EDTA), which showed the second best sealer penetration. Group III (5% NaOCl + 9% etidronic acid) showed the least sealer penetration in this study.

[Table 2] denotes the ANOVA test used. By applying Tukey-Kramer multiple comparison test, there is no significant difference between mean values of measurement of lateral penetration of sealer into radicular dentin when Group I, Group II and Group III were compared to each other (P = 0.3598). [Graph 1] gives the comparison of mean values of measurement of lateral penetration of sealer into radicular dentin in Group I, Group II, and Group III.
Table 2: One-way analysis of variance test

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The addition of surfactants to NaOCl during the chemomechanical preparation of root canal would lead to clinical results that are superior to those achieved by the usage of NaOCl either with EDTA or with etidronic acid (HEBP).


  Discussion Top


An ideal root canal irrigant should have tissue-dissolving activity, antimicrobial action, demineralization potential, lubrication, and smear layer removal capacity. Due to the complex nature of the root canal and its anatomical variations, the bacterial count of root canal reduces 100–1000 folds after biomechanical preparation. However, 35%–50% of the root canal is devoid of complete biomechanical preparation. For maximum root canal disinfection, endodontic irrigants play a vital role.[3] When it comes to maximum disinfection of the root canal, NaOCl is a much-revered irrigant. NaOCl has brilliant antimicrobial action and tissue dissolution property. However, NaOCl comes with its own set of flaws, namely its inability to take care of the sludge which is formed post dissolution of pulp tissue, lack of substantivity, no smear layer removing ability and its vulnerability in the face of accumulated debris in the form of cleaved and shaved dentin and tissue remnants leading to its neutralization making its use somewhat unsatisfactory. This leads to a decrease in the availability of free chlorine.[3] In addition to the above, NaOCl also displays severe toxicity to healthy living tissue if extruded beyond the apical foramen.

Therefore, the classic protocol of irrigation includes the use of NaOCl, followed by the use of saline as an intermittent wash and then using a chelating solution such as ethylenediaminetetraacetic acid or HEBP for elimination of smear layer.[3] Theoretically, this protocol can be simplified in different ways; they are as follows: use of a chelator that fails to interfere with the action of NaOCl or use of a chelator that has a strong disinfecting ability when used as a final irrigant. NaOCl and etidronic acid combination can be used solely for biomechanical preparation to avoid the formation of a smear layer.[4]

To overcome the drawbacks of NaOCl, where NaOCl does not eradicate the smear layer after the preparation of the root canal, chelating agents such as 17% EDTA or 10% citric acid (CA) or 18% etidronic acid (HEBP) need to be used to effectively remove the smear layer.[5] Another drawback of NaOCl is its lack of substantivity.[6] Chlorhexidine (CHX) has one of its potent properties as an antimicrobial effect. For more beneficial effect of NaOCl, it is compounded with CHX to endure its antimicrobial action.[3]

A study was conducted by Grawehr et al.[7] where EDTA resulted in decreasing the ability to dissolve tissue using NaOCl. NaOCl is unable to reduce the chelation of calcium or removal of smear layer by other chelating agents such as CA and EDTA.[5]

Conventional NaOCl exhibits high surface tension which is considered as a major disadvantage of this solution. Hence, surfactants are added to NaOCl which leads to reduction in surface tension, and hence, the irrigant is better able to penetrate the canal irregularities and dentinal tubules.[3]

Clarkson et al.[8] inferred from their study that products with surface-active agents led to depletion of chlorine ions of NaOCl at some of the dilutions. They also demonstrated that increased pulp tissue dissolution occurred when surface tension of NaOCl was reduced.

Mohammadi et al.[3] in their study demonstrated Chlor-XTRA to be more potent against microorganisms such as Actinomyces israelii when compared to CHX, Hypoclean, and Tetraclean. Jungbluth et al.[9] demonstrated that various bottles containing Chlor-XTRA exhibited different amounts of chlorine. Stojicic et al.[10] from their study concluded that a significant amount of pulp tissue dissolution was seen upon the use of Chlor-XTRA.

Etidronic acid is a hypochlorite–chelator combination that decreases the accumulation of dentinal debris during mechanical instrumentation. HEBP has proved to be an alternative to EDTA as it is a mild chelator and effectively removes the smear layer formed post instrumentation.[11] Zehnder et al.[12] assessed the interactions of EDTA, HEBP, and CA with NaOCl and stated that the bactericidal efficacy of NaOCl was not hindered by HEBP when used in combination.[12] Lottanti et al.[4] stated that the elimination in the smear layer of instrumented root canals was possible by a protocol using HEBP in a manner similar to conventional EDTA. Neelakantan et al.[13] recommended that HEBP should always be mixed with NaOCl and then used and also stated that it should not be used as a final rinse because etidronic acid is a weak decalcifying agent.

Due to pseudoplastic behavior of AH Plus within the canal lumen, it exhibited superior penetration and adaptation to the canal walls. This means that due to an increase in the shear rate observed during obturation, there is a reduction in the viscosity and an increase in flow of AH Plus sealer.[14] Rhodamine B was the dye used in this study. It is a fluorescent dye with a maximum absorption wavelength of 540 nm. However, it is recommended that fluoro-6 should be used rather than rhodamine B to label calcium silicate-based sealers due to the lesser affinity for calcium in calcium silicate-based sealers by rhodamine B, and this was studied by Russell et al. in 2017.[14]

[Figure 1] depicts the fluorescence microscopic images for Group I (control group). As per the results of the current study, of the three experimental groups, NaOCl with surfactants showed maximum penetration of sealer into the radicular dentin [Figure 2]. The least penetration of sealer was noted in the NaOCl with HEBP group [Figure 3]. This shows that the cleaning efficacy of NaOCl with HEBP group was comparatively less with respect to NaOCl with surfactant group.
Figure 1: Fluorescence microscopic images of Group I: Control group

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Figure 2: Fluorescence microscopic images of Group II: Sodium hypochlorite with surfactant group

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Figure 3: Fluorescence microscopic images of Group III: Sodium hypochlorite with etidronic acid group

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Beust in 1931 first photographed an optical phenomenon known as the “butterfly effect,” while he was examining few cross sections of the roots of teeth. Different patterns of dentinal tubular sclerosis are seen in the buccolingual and mesiodistal directions. When the transverse sections of tooth roots are examined, a characteristic butterfly effect is noted. This was observed by Vasiliadis et al. They also observed that sclerosed dentin appeared to be more translucent than normal dentin and dentinal tubules cause refraction and scattering of light.[15]

Hence, better antibacterial effects are observed when there is deeper sealer penetration. Therefore, the lesser sealer penetration in teeth with butterfly effect may have a negative impact on root canal treatment outcome.[14]

The limitations of the present study may include the technique of obturation used, chemical and physical properties of the sealer used, and configuration of the root canals. Other limitations include that the tooth type and age of the patient were not taken into consideration which may have led to differences in the results obtained.


  Conclusions Top


Within the limitations of this study, we could conclude that the cleaning efficacy of modifications to NaOCl provided results similar to the conventional irrigation protocol and hence could be used as a stand-alone irrigant.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Zehnder M. Root canal irrigants. J Endod 2006;32:389-98.  Back to cited text no. 1
    
2.
Cameron JA. The effect of a fluorocarbon surfactant on the surface tension of the endodontic irrigant, sodium hypochlorite. A preliminary report. Aust Dent J 1986;31:364-8.  Back to cited text no. 2
    
3.
Mohammadi Z, Shalavi S, Moeintaghavi A, Jafarzadeh H. A review over benefits and drawbacks of combining sodium hypochlorite with other endodontic materials. Open Dent J 2017;11:661-9.  Back to cited text no. 3
    
4.
Lottanti S, Gautschi H, Sener B, Zehnder M. Effects of ethylenediaminetetraacetic, etidronic and peracetic acid irrigation on human root dentine and the smear layer. Int Endod J 2009;42:335-43.  Back to cited text no. 4
    
5.
Mohammadi Z, Giardino L, Palazzi F, Asgary S. Agonistic and antagonistic interactions between chlorhexidine and other endodontic agents: A critical review. Iran Endod J 2015;10:1-5.  Back to cited text no. 5
    
6.
Mohammadi Z, Giardino L, Mombeinipour A. Antibacterial substantivity of a new antibiotic-based endodontic irrigation solution. Aust Endod J 2012;38:26-30.  Back to cited text no. 6
    
7.
Grawehr M, Sener B, Waltimo T, Zehnder M. Interactions of ethylenediamine tetraacetic acid with sodium hypochlorite in aqueous solutions. Int Endod J 2003;36:411-7.  Back to cited text no. 7
    
8.
Clarkson RM, Podlich HM, Moule AJ. Influence of ethylenediaminetetraacetic acid on the active chlorine content of sodium hypochlorite solutions when mixed in various proportions. J Endod 2011;37:538-43.  Back to cited text no. 8
    
9.
Jungbluth H, Peters C, Peters O, Sener B, Zehnder M. Physicochemical and pulp tissue dissolution properties of some household bleach brands compared with a dental sodium hypochlorite solution. J Endod 2012;38:372-5.  Back to cited text no. 9
    
10.
Stojicic S, Zivkovic S, Qian W, Zhang H, Haapasalo M. Tissue dissolution by sodium hypochlorite: effect of concentration, temperature, agitation, and surfactant. J Endod 2010;36:1558-62.  Back to cited text no. 10
    
11.
Mariyam NF, Subbarao C. Effectiveness of sodium hypochlorite and etidronic acid in combination as a root canal irrigant with varying apical preparation sizes – An in vitro analysis. J Pharm Sci Res 2017;9:716-8.  Back to cited text no. 11
    
12.
Zehnder M, Schmidlin P, Sener B, Waltimo T. Chelation in root canal therapy reconsidered. J Endod 2005;31:817-20.  Back to cited text no. 12
    
13.
Neelakantan P, Varughese AA, Sharma S, Subbarao CV, Zehnder M, De-Deus G. Continuous chelation irrigation improves the adhesion of epoxy resin-based root canal sealer to root dentine. Int Endod J 2012;45:1097-102.  Back to cited text no. 13
    
14.
Russell A, Friedlander L, Chandler N. Sealer penetration and adaptation in root canals with the butterfly effect. Aust Endod J 2018;44:225-34.  Back to cited text no. 14
    
15.
Mahajan S, Chawla D, Kaur J, Jain S. Macronutrients in Breastmilk of Mothers of Preterm Infants. Indian Pediatr 2017;54:635-7.  Back to cited text no. 15
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2]



 

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