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ORIGINAL RESEARCH
Year : 2019  |  Volume : 11  |  Issue : 5  |  Page : 51-58  

Time-dependent effect of various irrigants for root canal on smear layer removal


1 Department of Conservative Dentistry and Endodontics, People’s College of Dental Sciences and Research Centre, Bhopal, India
2 Department of Conservative Dentistry and Endodontics, Modern Dental College and Research Centre, Indore, Madhya Pradesh, India
3 Department of Prosthodontics Crown and Bridge, Al-Badar Dental College and Hospital, Kalaburagi, Karnataka, India
4 Department of Prosthodontics Crown and Bridge, Government Dental College and Hospital, Hyderabad, Telangana, India
5 Department of Preventive Dental Sciences, College of Dentistry, Dar Al Uloom University, Riyadh, Saudi Arabia

Date of Web Publication7-Feb-2019

Correspondence Address:
Dr. Shikha Singh
Department of Conservative Dentistry and Endodontics, People’s College of Dental Sciences and Research Centre, Bhopal, Madhya Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JPBS.JPBS_195_18

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   Abstract 


Background: Existence of smear layer in root canals caused by instrumentation is believed to prevent penetration of irrigating agents, thereby resulting in endodontic treatment. Aims and Objectives: To compare and evaluate the effectiveness of two irrigants: 17% ethylenediaminetetraacetic acid (EDTA) and mixture of tetracycline isomer, an acid, and a detergent (MTAD) as final agents for eliminating the smear layer. Materials and Methods: We included 50 human lower premolar teeth whose crowns were sectioned at cementoenamel junction. The sample was randomly grouped into five groups, each with 10 teeth. Group 1: 1mL of 17% EDTA as final rinse for 1min, Group 2: 1mL of 17% EDTA for 30s, Group 3: 5mL of MTAD for 2.5min, Group 4: 5mL of MTAD for 5min, and Group 5: saline. The specimens were sectioned vertically all along the long axis and fixed on an aluminum stub for gold ion sputtering. Scanning electron microscope was used to observe the specimens, and photomicrographs were taken at coronal, middle, and apical thirds of canal, and assessed by Torabinejad scoring system by two examiners, and the observations were analyzed statistically. Results: When Group 1 and Group 2 and Groups 3 and 4 were compared, we found a significant variation in removal of smear layer at cervical and middle thirds, and insignificant difference at apical third. In comparison with EDTA and saline, MTAD was more efficient significantly in middle and cervical thirds and insignificant at apical third. Conclusion: MTAD is an efficient irrigant for removing smear layer than EDTA and saline.

Keywords: Ethylenediaminetetraacetic acid, protaper, scanning electron microscope, sodium hypochlorite, smear layer


How to cite this article:
Singh S, Singh M, Salgar AR, Chandrahari N, Prathibha N, Koppolu P. Time-dependent effect of various irrigants for root canal on smear layer removal. J Pharm Bioall Sci 2019;11, Suppl S1:51-8

How to cite this URL:
Singh S, Singh M, Salgar AR, Chandrahari N, Prathibha N, Koppolu P. Time-dependent effect of various irrigants for root canal on smear layer removal. J Pharm Bioall Sci [serial online] 2019 [cited 2019 Aug 18];11, Suppl S1:51-8. Available from: http://www.jpbsonline.org/text.asp?2019/11/5/51/251802




   Introduction Top


Proper cleaning and shaping of root canals is the foremost requirement to attain successful root canal treatment. The factors, which contribute to failed endodontic treatment, include persistent microorganisms in root canals and also those that invade the dentinal tubules, irregular canal architecture, apical deltas, and narrow isthmi, thus necessitating chemical disinfection by irrigating solutions along with mechanical instrumentation. Various advancements have been introduced in the field of endodontics such as hand- and engine-driven instruments and new irrigating solutions.[1],[2]

A key feature in root canal therapy is smear layer removal, thereby enhancing the seal of the root canal filling.[2] Instrumentation produces an amorphous smear layer consisting of inorganic and organic material on root canal walls. Usually smear layer thickness is 1–2mm, but may extend deep into dentinal tubules as far as 40mm. It prevents the access of antimicrobial agents into the contaminated dentinal tubules.[3],[4],[5]

An ideal chemical irrigant should provide a physical flush for debris removal and also act as a tissue solvent, bactericidal agent, and lubricant.[4] Various irrigating solutions are chelating agents (ethylenediaminetetraacetic acid [EDTA]), acids (citric and phosphoric), alkaline solutions (sodium hypochlorite [NaOCl]), oxidative agents (hydrogen peroxide), and normal saline.[6],[7],[8]

We used NaOCl (hypo), EDTA, and a mixture of tetracycline isomer, an acid, and a detergent (MTAD) as irrigant solutions. Hypo is reported as the most effective root canal irrigant that can dissolve organic tissue.[9] Although chelating agents such as EDTA are being used in situations where demineralization of dentin is required, they have a disadvantage of incomplete smear layer removal, necessitating use of NaOCl as a final irrigant. MTAD has 3% doxycycline that acts as a broad-spectrum antibiotic, 4.25% citric acid that acts as a demineralizing agent, and 0.5% polysorbate 80 that acts as a detergent. Studies have shown it to be an effectual and biocompatible endodontic irrigant.[5],[6]

We carried out this study to compare and evaluate the time-dependent efficiency of two irrigants: 17% EDTA and MTAD as final irrigants for efficient smear layer removal at cervical, middle, and apical levels in teeth, which were prepared with protaper system.


   Materials and Methods Top


We included 50 human lower premolar teeth (single rooted) removed for periodontal reasons, after obtaining institutional ethical clearance. All the teeth were initially cleaned to eliminate any calculus and stains and preserved in 0.9% normal saline to avoid dehydration.

Inclusion criteria were as follows:

  1. Sound, lower premolar with single root canal


  2. Teeth whose roots are completely formed


  3. Teeth with patent canals


  4. Teeth without anatomic variations


Exclusion criteria were as follows:

  1. Teeth having open apices


  2. Calcified canals


  3. Multi-rooted teeth


  4. Variations in the radicular anatomy


The guidelines of the Occupational Safety and Health Administration and Center for Disease Control and Prevention were followed. Entire modus operandi for preparation and irrigation was standardized and carried out by a single operator. Initially the crowns of sample teeth were sectioned at cementoenamel junction by a diamond disk mounted on a straight micromotor handpiece [Figure 1]. By using barbed broaches, pulp was extirpated and by using a no. 15 K-file, the patency of canals was found, and the working lengths were recognized by means of a no. 10 file. Instrumentation was carried out by protaper rotary files to master apical size no. 30 in a crown down technique, irrigating with 1mL of 5% NaOCl [Figure 2].
Figure 1: Decoronating the sample

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Figure 2: Cleaning and shaping done with protaper system

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Then the sample was randomly divided into five investigational groups, each with 10 teeth.

  1. Group 1: 1mL 17% EDTA for 1min as final rinse.


  2. Group 2: 1mL 17% EDTA for 30s.


  3. Group 3: 5mL MTAD for 2.5min.


  4. Group 4: 5mL MTAD for 5min.


  5. Group 5: Irrigated with saline.


To make sure that each irrigant has an even and direct contact with the root canal walls, a no. 15 barbed broach, draped with cotton, was soaked in solution and placed all along the total working length for approximately 4min, then the broach was moved up and down gently. Then all the canals of specimen were irrigated with 10 mL of sterile distilled water and dried with absorbent paper points.

All the teeth were sectioned along the long axis by a diamond disk alongside the root, thus creating a straight canal. By means of a chisel, splitting of teeth was carried out. Randomly one-half of each tooth was chosen and kept in 2% glutaraldehyde solution for 12h, the other half was discarded. Later, the specimens were dehydrated by graded concentration of ethanol (starting from 30%, 50%, 70%, 90%, and 100%). For gold ion sputtering, the specimens were fixed on an aluminum stub. Scanning electron microscope (SEM; 10kV accelerating voltage) was used to view the specimens, and photomicrographs were taken at 1000× magnification of representative area of the apical, middle, and coronal thirds of each canal [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]. After coding the specimens, they were observed by evaluators who were ignorant of the history of specimens. Two evaluators scored the presence or absence of smear layer in root canals by scoring system of Torabinejad et al. (2003),[8] and the results were statistically analyzed.[9]
Figure 3: Scanning electron microscope images of Group 1 specimen (irrigation with 17% ethylenediaminetetraacetic acid for 1min)

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Figure 4: Scanning electron microscope images of Group 2 specimen (irrigation with 17% ethylenediaminetetraacetic acid for 30s)

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,
Figure 5: Scanning electron microscope images of Group 3 specimen (irrigation with mixture of tetracycline isomer, an acid, and a detergent for 2.5min)

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,
Figure 6: Scanning electron microscope images of Group 4 specimen (irrigation with mixture of tetracycline isomer, an acid, and a detergent for 5min)

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Figure 7: Scanning electron microscope images of Group 5 specimen (control group: saline)

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Scoring system was carried out as follows:

  1. No smear layer: absence of smear layer and all tubules were clean and open.


  2. Moderate smear layer: absence of smear layer but tubules contained debris.


  3. Heavy smear layer: smear layer covered the root canal surface and the tubules.



   Results Top


The tabulated observations were statistically analyzed by chi-square test. No smear layer was seen at the cervical level in 8 (80%) samples of Group 1 and 3 (30%) samples of Group 2, whereas moderate smear layer was seen in 2 (20%) of Group 1 and 7 (70%) of Group 2, with a statistically significant difference in cervical scores between the groups (P = 0.025) [Table 1].
Table 1: Cervical scores among Group 1 (17% ethylenediaminetetraacetic acid for 1min) and Group 2 (17% ethylenediaminetetraacetic acid for 30s)

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Absence of smear layer was seen at the middle level in 8 (80%) samples of Group 1 and 2 (20%) of Group 2. However, moderate smear layer was observed in 2 (20%) of Group 1 and 8 (80%) of Group 2, with a statistically significant difference in middle scores between the groups (P = 0.007) [Table 2].
Table 2: Middle scores among Group 1 (17% ethylenediaminetetraacetic acid for 1min and Group 2 (17% ethylenediaminetetraacetic acid for 30s)

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Moderate smear at the apical level was seen in 7 (70%) samples of Group 1 and 6 (60%) of Group 2, whereas heavy smear layer was observed in 3 (30%) of Group 1 and 4 (40%) of Group 2. The difference among groups was statistically not significant (P = 0.639) [Table 3].
Table 3: Apical scores among Group 1 (17% ethylenediaminetetraacetic acid for 1min) and Group 2 (17% ethylenediaminetetraacetic acid for 30s)

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No smear layer was seen at the cervical level in 9 (90%) samples of Group 4 and 4 (40%) of Group 3 and moderate smear layer in 1 (10%) of Group 4 and 6 (60%) of Group 3, with a statistically significant difference among Groups 3 and 4 (P = 0.019) [Table 4].
Table 4: Cervical scores among Group 3 (mixture of tetracycline isomer, an acid, and a detergent for 2.5min) and Group 4 (mixture of tetracycline isomer, an acid, and a detergent for 5min)

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No smear layer was seen at the middle level in 8 (80%) samples of Group 4 and 3 (30%) of Group 3, whereas moderate smear layer was observed in 2 (20%) of Group 4 and 7 (70%) of Group 3. The difference being statistically significant (P = 0.025) [Table 5].
Table 5: Middle scores among Group 4 (mixture of tetracycline isomer, an acid, and a detergent for 5min) and Group 3 (mixture of tetracycline isomer, an acid, and a detergent for 2.5min)

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No smear layer was seen at the apical level in 2 (20%) samples of Group 4, moderate smear layer was seen in 6 (60%) of Group 4 and 6 (60%) of Group 3, and heavy smear layer was seen in 3 (30%) samples of Group 3. The difference in apical scores among the groups was statistically not significant (P = 0.231) [Table 6].
Table 6: Apical scores among Group 4 (mixture of tetracycline isomer, an acid, and a detergent for 5min) and Group 3 (mixture of tetracycline isomer, an acid, and a detergent for 2.5min)

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At the cervical level, no smear layer was seen in 11 (55%) samples of EDTA Group and 13 (65%) samples of MTAD Group, whereas moderate smear layer was observed in 9 (45%) of EDTA Group and 7 (35%) of MTAD Group. The difference in cervical scores between the groups was statistically insignificant (P = 0.519) [Table 7].
Table 7: Cervical scores among ethylenediaminetetraacetic acid and mixture of tetracycline isomer, an acid, and a detergent

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At the middle level, absence of smear layer was noticed in 10 (50%) samples of EDTA Group and 11 (55%) samples of MTAD Group, whereas moderate smear layer was noticed in 10 (50%) of EDTA Group and 9 (45%) of MTAD Group. The difference in middle scores between the groups was also statistically not significant (P = 0.752) [Table 8].
Table 8: Middle scores among ethylenediaminetetraacetic acid and mixture of tetracycline isomer, an acid, and a detergent

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At the apical level, no smear layer was seen in 3 (15%) samples of MTAD Group, moderate smear layer was seen in 12 (60%) of EDTA Group and 13 (65%) of MTAD Group, and heavy smear level was observed in 7 (35%) samples of EDTA Group and 5 2 (5%) samples of MTAD Group. The difference in apical scores was statistically insignificant (P = 0.185) [Table 9].
Table 9: Apical scores among ethylenediaminetetraacetic acid and mixture of tetracycline isomer, an acid, and a detergent

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   Discussion Top


Successful endodontic management is based on meticulous removal of pulpal remnants, debris, and also total elimination of the smear layer.[8],[9],[10] During instrumentation by hand or rotary instruments, the mineralized tissues get shattered to generate considerable quantity of debris, consisting of very minute units of mineralized collagen matrix, which gets spread over the surface forming the so-called smear layer.[11],[12],[13]

Controversy still exists whether to get rid of the smear layer or not. Few authors suggest to retain it as it prevents apical microleakage. However many authors advocate its removal as it consists of bacteria that can multiply in the dentinal tubules, thereby acting as a reservoir. It may also act as a barrier between the canal wall and filling materials, thus preventing the creation of an acceptable seal.[14],[15],[16]

The volume of irrigant and its contact time are the main factors to be considered for effectual smear layer removal. Orstavik and Haapasalo[9] suggested the need of patent dental tubules by removing the smear layer, in diminishing the time needed for complete disinfection, as supported by Bystrom and Sundqvist.[10]

We evaluated the time-dependent outcome of MTAD and EDTA, following with 5.25% NaOCl irrigation on intracanal smear layer removal after instrumentation of the canals. The complete length of canal was used to test the efficacy of solution in all parts of root including apical third. We used SEM to find out the efficiency of used irrigants to remove the smear layer.

We found that in control group where saline was used as an irrigant, ineffective smear layer removal was observed, thus saline was considered as ineffective. When Group 1 (17% EDTA used for 1min) and Group 2 (17% EDTA used for 30s) were compared, we found a significant difference in removal of smear layer at middle and cervical thirds and insignificant difference at apical third. Our findings are in accord with the findings by Kuruvilla et al.,[11] Calt and Serper,[12] and Torabinejad et al.[8]

We found a significant difference in smear layer removal at cervical and middle thirds and insignificant difference at apical third among Group 3 (MTAD for 2.5min) and Group 4 (MTAD for 5min). Giardino et al.[13] reported that the dentin wall surfaces treated with MTAD appeared clean and orifices of dentinal tubules were free of smear plugs.

When MTAD, EDTA, and saline were compared for effective smear layer removal, the former irrigant appeared more effectual than the latter two, especially if used along with 5.25% NaOCl, which was similar to the findings by Zhang et al.[15] and Zehnder.[14] The difference was significant in middle and cervical thirds and insignificant at apical third.

At present, no precise recommendation regarding the optimal duration EDTA should be left in the canal removal exists. Prolonged irrigation with chelating agents might weaken dentin. Kuah et al.[16] recommended 1min EDTA application as effective time, similar to 3-min application for removal of smear layer, whereas Torabinejad et al.[8] also found that effective smear layer removal and cleaner dentinal tubules in the apical third of canals were achieved after treating canals with MTAD than that with EDTA.[12]

When EDTA was used along with 5.25% NaOCl alternatively, the smear layer was totally removed in the middle and coronal thirds but was less effectual in the apical third. This might be due to insufficient volume or penetration of the irrigant into the apical part of the canal during irrigation.[3] One vital feature to be noted during irrigation is that the agent should not reach more than 1mm apically from the needle tip.[15] Abou-Rass and Piccinino[17] were of the belief that the needle of syringe used for irrigation should be in close proximity for the irrigant to create contact in removing material or debris, with a 30-gauge needle being the most efficient in reaching sufficient depth.[17]

Limitations

  1. Lower sample size


  2. Ultrasonic activation of irrigation solutions should have been analyzed


Future research direction

Further studies on a larger sample at different hospital setups should be carried out to arrive at a precise concentration and duration of various irrigant solutions.


   Conclusion Top


MTAD as a final rinse is an efficient irrigant for removal of smear layer in comparison with saline and EDTA. Further studies should be conducted on a larger sample to find out the most efficient smear layer removing agent, thereby achieving successful endodontic therapy.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Aksel H, Serper A. Concentration and time-dependent effect of initial sodium hypochlorite on the ability of QMix and ethylenediaminetetraacetic acid to remove smear layer. J Conserv Dent 2017;20:185-9.  Back to cited text no. 1
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2.
Mittal A, Dadu S, Yendrembam B, Abraham A, Singh NS, Garg P. Comparison of new irrigating solutions on smear layer removal and calcium ions chelation from the root canal: an in vitro study. Endodontology 2018;30:55-61.  Back to cited text no. 2
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Palaniswamy U, Kaushik M, Surender LR, Prashar N, Arya S, Pasari S. A SEM evaluation of smear layer removal using two rotary instrument systems with EDTA and vinegar as a root canal irrigant. J Res Dent 2016;4:17-21.  Back to cited text no. 3
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Kamble AB, Abraham S, Kakde DD, Shashidhar C, Mehta DL. Scanning electron microscopic evaluation of efficacy of 17% ethylenediaminetetraacetic acid and chitosan for smear layer removal with ultrasonics: an in vitro study. Contemp Clin Dent 2017;8:621-6.  Back to cited text no. 4
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Berastegui E, Molinos E, Ortega J. To comparison of standard and new chelating solutions in endodontics. J Dental Sci 2017;2:000131.  Back to cited text no. 5
    
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Al-Mafrachi RM, Awazli LG, Al-Maliky MA. Investigation of the effect of Er:Cr:Ysgg laser 2780nm in comparison with xp-endo finisher on root canal dentin permeability and smear layer removal: an in vitro study. Dent Health Curr Res 2018;4:2.  Back to cited text no. 6
    
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Bayram HM, Bayram E, Kanber M, Celikten B, Saklar F. Effect of different chelating solutions on the push-out bond strength of various root canal sealers. Biomed Res—India 2017;401-6.  Back to cited text no. 7
    
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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. 8
    
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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. 9
    
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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. 10
    
11.
Kuruvilla A, Jaganath BM, Krishnegowda SC, Ramachandra PK, Johns DA, Abraham A. A comparative evaluation of smear layer removal by using EDTA, etidronic acid, and maleic acid as root canal irrigants: an in vitro scanning electron microscopic study. J Conserv Dent 2015;18:247-51.  Back to cited text no. 11
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Calt S, Serper A. Time-dependent effects of EDTA on dentin structures. J Endod 2002;28:17-9.  Back to cited text no. 12
    
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Giardino L, Ambu E, Becce C, Rimondini L, Morra M. Surface tension comparison of four common root canal irrigants and two new irrigants containing antibiotic. J Endod 2006;32:1091-3.  Back to cited text no. 13
    
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Zehnder M. Root canal irrigants. J Endod 2006;32:389-98.  Back to cited text no. 14
    
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Zhang W, Torabinejad M, Li Y. Evaluation of cytotoxicity of MTAD using the MTT-tetrazolium method. J Endod 2003;29: 654-7.  Back to cited text no. 15
    
16.
Kuah HG, Lui JN, Tseng PS, Chen NN. The effect of EDTA with and without ultrasonics on removal of the smear layer. J Endod 2009;35:393-6.  Back to cited text no. 16
    
17.
Abou-Rass M, Piccinino MV. The effectiveness of four clinical irrigation methods on the removal of root canal debris. Oral Surg Oral Med Oral Pathol 1982;54:323-8.  Back to cited text no. 17
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9]



 

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