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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 31  |  Issue : 1  |  Page : 72-77

Efficacy of smear layer removal by two Ayurvedic herbal irrigants, using continuous vs. syringe and needle irrigation


Department of Conservative Dentistry and Endodontics, College of Dental Science and Hospital, Indore, Madhya Pradesh, India

Date of Web Publication19-Jun-2019

Correspondence Address:
Dr. Rajeshwar Singh
5/2 Snehlata Ganj, Narayan Niwas, Indore - 452 003, Madhya Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/endo.endo_28_18

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  Abstract 

Introduction: A successful root canal therapy is largely dependent on thorough chemo-mechanical debridement of the root canal space. However, mechanical preparation inadvertently forms an amorphous layer, known as the “smear layer.” Traditionally used irrigants have a deleterious effect over root dentin and thus herbal alternatives can be a better option for smear layer removal with no action on root dentin.
Aim: The purpose of the study was to compare the in vitro effectiveness of two potential herbal irrigants: 6% German chamomile extract (GCE) and 6% Morinda citrifolia juice (MCJ), in removal of smear layer.
Materials and Methods: Eighty single-rooted human teeth were allocated into two equal groups: one to be instrumented with the self-adjusting file (SAF), while the other with WaveOne (WO). Four subgroups in each group were irrigated with 6% GCE, 6% MCJ, 17% ethylenediaminetetraacetic acid (EDTA) (positive control), and NS (negative control). Scanning electron microscopy (SEM) was used to evaluate the presence of smear layer.
Statistical Analysis: As data for smear layer were categorical, Chi-square test was applied for data analysis. P < 0.05 was considered statistically significant.
Results: The most effective smear layer removal in the coronal part was observed with SAF-EDTA and SAF-GCE, followed by WO-EDTA. In the middle part, SAF-GCE was equivalent to that of SAF-EDTA, followed by WO-EDTA and WO-GCE. In the apical third, the most efficient smear layer removal was observed with SAF-EDTA, followed by some removal of smear layer by WO-EDTA and SAF-GCE. GCE was as effective as EDTA in removal of smear layer in the coronal and mid-root regions, when used with continuous irrigation.

Keywords: German chamomile, self-adjusting file, smear layer


How to cite this article:
Saha SG, Singh R, Bhardwaj A, Vijaywargiya P, Billore J, Saxena D. Efficacy of smear layer removal by two Ayurvedic herbal irrigants, using continuous vs. syringe and needle irrigation. Endodontology 2019;31:72-7

How to cite this URL:
Saha SG, Singh R, Bhardwaj A, Vijaywargiya P, Billore J, Saxena D. Efficacy of smear layer removal by two Ayurvedic herbal irrigants, using continuous vs. syringe and needle irrigation. Endodontology [serial online] 2019 [cited 2019 Jul 23];31:72-7. Available from: http://www.endodontologyonweb.org/text.asp?2019/31/1/72/260524


  Introduction Top


A successful root canal therapy is largely dependent on thorough chemo-mechanical debridement of the root canal space. However, mechanical preparation inadvertently forms an amorphous layer, known as the “smear layer,” created over the instrumented dentinal walls. This smear layer may provide an environment for microorganisms to thrive and thus its removal is essential and imperative for successful treatment outcomes.[1] Ethylenediaminetetraacetic acid (EDTA), which is a chelating agent, is commonly used to remove the smear layer and is considered to be a gold standard for removal of smear layer.[2]

Nevertheless, a prolonged exposure to EDTA has been shown to weaken the root dentin,[3] and the antibacterial activity of EDTA is very limited.[3]

Two potential herbal solutions may be considered as potential irrigants for smear layer removal: 6% German chamomile extract (GCE)[4] and 6% Morinda citrifolia juice (MCJ).[5]

GCE is an extract of the dried flowers of the plant Matricaria recutita, commonly known as “German chamomile.” It is one of the most commonly used herbs for medicinal purposes in Ayurvedic medicine.[6] This extract has antimicrobial activity,[6],[7] anti-inflammatory effect,[8] and antioxidant property.[8] It also contains acids such as capric acid, o-coumaric acid, p-coumaric acid, dihydroxybenzoic acid, and caprylic acid,[1] with a pH of 7.6.

MCJ has a broad range of therapeutic effects such as antibacterial, antiviral, antifungal, as well as analgesic effects. It has also been found to be an herbal irrigant that is effective in smear layer removal when used at a concentration of 6%.[2] The use of MCJ may potentially be advantageous as an endodontic irrigant because it is a biocompatible antioxidant and has no adverse effects.[9] MCJ comprises milder acids which may be responsible for its reported smear layer removal action.[10] MCJ at 6% concentration has a pH of 3.5.

The purpose of this study was to compare the in vitro effectiveness of two potential herbal irrigants: GCE and MCJ, in removal of the smear layer created during instrumentation.


  Materials and Methods Top


Teeth

Eighty single-rooted permanent human teeth, with fully developed apices, were selected from a pool of recently extracted teeth that were extracted for therapeutic reasons not related to the present study. All the selected teeth had a length in the range of 21–25 mm with intact crown and root. The teeth were radiographed both buccolingually and mesiodistally to confirm the presence of single canal. The teeth not fulfilling any of the above-mentioned criteria were excluded from the study. The surface of the selected teeth was cleaned using a ultrasonic scaler and the teeth were stored in distilled water until use.[11]

Sample preparation

The teeth were decoronated at the cementoenamel junction using a diamond disc to obtain a standardized root length. A size 10 or 15 K-type file (Dentsply, Maillefer, Ballaigues, Switzerland) was introduced into the root canal until it could be seen at the apical foramen, after which it was withdrawn to be within the apical foramen and this was defined as the working length.[4]

Irrigants

Four irrigants were used in the present study: GCE 6% (Navchetana Kendra, New Delhi, India) and MCJ 6% (Navchetana Kendra, New Delhi, India). EDTA, 17% (Ogna, Muggio, Italy) served as a positive control and normal saline (NS) served as a negative control.

Experimental design

The samples were divided randomly (Statistical package for the social sciences (IBM) random sample generator) into two equal groups according to the file and irrigation system to be used for canal preparation:

  • Group I (n = 40) to be instrumented with the self-adjusting file (SAF) system (ReDent-Nova, Raanana, Israel) with continuous irrigation and Group II (n = 40) to be instrumented with the WaveOne (WO) file system with intermitted syringe and needle irrigation (Dentsply, Maillefer, Ballaigues, Switzerland)
  • Groups I and II were further subdivided into four subgroups each (n = 10), according to the irrigant to be used: GCE, MCJ, and EDTA which served as a positive control and NS (NS) which served as a negative control. The resulting subgroups were as follows: Group I: SAF-GCE, SAF-MCJ, SAF-EDTA, and SAF-NS and Group II: WO-GCE, WO-MCJ, WO-EDTA, and WO-NS.


Group I – Self-adjusting file instrumentation with continuous irrigation

The samples in this group were instrumented using the SAF system, with continuous, simultaneous irrigation, with each of the tested irrigants, delivered by a VATEA peristaltic pump (ReDent-Nova), which is an integral part of the SAF system. The flow rate of the irrigants was set at 4 ml/min, and the SAF file was used in the canal for 2 min, at 5000 in-and-out vibrations per minute and with manual pecking motion. The samples were then finally flushed with NS for 1 min.

Group II – WaveOne instrumentation with intermittent syringe and needle irrigation

The samples were instrumented using the WO file system. Each of the irrigants was delivered into the canal using a syringe with a 30G side-vented needle (Pro-rinse endo irrigation needles, Dentsply, Maillefer, Ballaigues, Switzerland) that was inserted into the canal as far as it could go at each stage, without binding. The irrigant was used before instrumentation, as well as each time that the file was removed for cleaning its flutes, at a flow rate of 4 ml/min. The total delivery time of the irrigant was 2 min during and immediately after the canal preparation. This was followed by a final flush of NS for 1 min.

Sodium hypochlorite was not used as an irrigant in any of the samples in either Group I or Group II in this study.

Preparation for scanning electron microscopy

After cleaning and shaping, two longitudinal grooves were prepared on the buccal and lingual surfaces of each root, using a diamond disc, without penetrating the canal. The roots were then split into two halves with a chisel and mallet.

The samples were then gold sputtered and examined under scanning electron microscope (ESEM Quanta 200, Canada, USA) at a magnification of ×1500, for the presence or absence of smear layer at the coronal, middle, and apical regions.

Evaluation of smear layer removal

The presence or absence of smear layer was scored according to the rating system as follows: Score A – complete removal of smear layer and all tubules visible, Score B – partial removal of smear layer and some dentinal tubules visible, and Score C – no removal of smear layer and no dentinal tubules visible. The scale was used in accordance to the scoring criteria formulated by Madison and Hokett, with the numeric values being replaced by alphabetic letters (A–C).[12]

Statistical analysis

As data for smear layer were categorical, Chi-square test was applied for data analysis. P < 0.05 was considered statistically significant. Data analysis was performed using version 21.0 of the Statistical Package for the Social Sciences software (IBM Corporation, Armonk, New York, USA).


  Results Top


The results are presented in [Table 1], [Table 2], [Table 3] and [Figure 1] and [Figure 2].
Table 1: Smear layer removal scores at the coronal level

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Table 2: Smear layer removal scores at the middle level

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Table 3: Smear layer removal scores at the apical level

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Figure 1: Representing scanning electron microscope images (×1500) of the subgroups of Group I (self-adjusting file) at coronal, middle, and apical levels. Note: Excessive demineralization of the dentin in the middle parts of the canal in the self-adjusting file-ethylenediaminetetraacetic acid group. The German chamomile extract was more effective in removal of smear layer than Morinda citrifolia juice

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Figure 2: Representing scanning electron microscope images (×1500) of the subgroups of Group II (Wave One) at coronal, middle and apical level. Note: The German chamomile extract was more effective in removal of smear layer than Morinda citrifolia juice

Click here to view


Coronal sections

Complete removal of the smear layer (Score A) was observed in 100% of the samples (n = 10), when instrumented-irrigated with SAF-EDTA and SAF-GCE, with no difference between the groups. SAF-EDTA and SAF-GCE groups presented with significantly better results when compared to SAF-MCJ and SAF-NS (P < 0.05).

In the coronal sections, WO-EDTA group showed better removal of smear layer (60% samples scored “A”) in comparison with the other three subgroups of Group II. There was no significant difference between the other groups (P > 0.05) in coronal sections.

Middle sections

Complete removal of smear layer (Score A) was observed in 100% (n = 10) of the samples in SAF-GCE group, while 90% samples showed complete smear layer removal in the SAF-EDTA group. However, there was no statistically significant difference between SAF-GCE and SAF-EDTA groups (P > 0.05). SAF-EDTA and SAF-GCE groups showed statistically significantly better results than SAF-MCJ, SAF-NS, WO-MCJ, and WO-NS groups (P < 0.05). In WO-EDTA group, complete removal of smear layer was observed in 60% of the samples, which was significantly superior than the other groups instrumented with WO file system. There was no significant difference between the other groups (P > 0.05) in middle sections.

Furthermore, in SAF-GCE group, significantly better removal of smear layer was observed than WO-GCE group (P < 0.05), though there was no significant difference between SAF-EDTA and WO-GCE groups (P > 0.05).

The results revealed that in the middle part of the root, SAF-GCE presented better cleaning efficacy, i.e., 100% of the samples with score “A,” followed by SAF-EDTA (90% of the samples), WO-EDTA (60% samples), and then WO-GCE (30% of the samples).

Many samples in the SAF-EDTA group showed signs of excessive demineralization and calcospherites could be observed [Figure 1].

Apical sections

Complete removal of smear layer (Score A) was observed in 40% of the samples of the SAF-EDTA group. Score “B” was observed in the WO-EDTA group in 70% of the samples, followed by 60% samples of the SAF-EDTA group and 50% of the samples of the SAF-GCE group. However, there was no significant difference between these three groups (P > 0.05).

SAF-EDTA group showed more significant smear layer removal than SAF-MCJ, SAF-NS, WO-GCE, WO-MCJ, and WO-NS groups (P < 0.05). There was no significant difference between the latter groups (P > 0.05) in apical sections.

Most of the samples of the apical part that belonged to the SAF-MCJ, SAF-NS, WO-GCE, WO-MCJ, and WO-NS groups were completely covered with smear layer (Score C).


  Discussion Top


Endodontic instrumentation either hand or rotary during root canal preparation produces an amorphous compacted layer within the dentinal tubules comprising the smear layer.[2]

Studies[1] have suggested that the presence of smear layer can jeopardize the long-term success of root canal therapy, making its removal mandatory.

Presence of smear layer alters the permeability of the dentin, thus interfering with the formation of an adequate apical and coronal seal of the root canal, thereby leading to microleakage.[1]

An ideal smear layer-removing agent should eliminate both the organic and inorganic phases from the canal surfaces without exerting harmful erosive effects over the dentin or the periapical tissues.[1]

The most common root canal irrigant used for effective smear layer removal is EDTA, which is a chelating agent that reacts with the calcium ions in the dentin-forming soluble calcium chelates.[12]

It has been also revealed that EDTA has an erosive effect on the dentin when exposed to the solution for a prolonged period of time.[13],[14] In addition, EDTA lacks antibacterial properties and thus has a very minimal effect on the microorganisms harboring in the root canal.[3]

It was also observed in some samples in the present study that EDTA leads to excessive demineralization of the root canal wall and exposure of calcospherites, especially in the mid-root and coronal sections, leading to potential damage of the dentin wall [Figure 1].

Therefore, a shift in focus has taken place toward the search for more biocompatible substitutes over the traditionally used irrigants. The use of herbal irrigants may thus be of interest to endodontic professionals as a part of the increasing trend to seek natural remedies for root canal treatment.

Studies have proved herbal irrigants to be effective against the micro flora of the root canal system,[14] making them a viable option to be tested for smear layer removal action along with their other beneficial actions.

In the present study, the entire root canal length was utilized to simulate the clinical situation and to test the efficacy of the irrigating solutions in all segments of the root canal system. SEM was used to assess the effectiveness of various natural and conventional root canal irrigants in removing the smear layer.[2]

In the present study, 6% GCE showed smear layer-removing properties comparable to that of EDTA in the coronal and middle sections of root canal when used in conjunction with SAF system that allowed continuous irrigation, through the hollow file.

The SAF system consistently showed better smear layer-removing capacity when compared to WO file system which was used with conventional intermittent irrigation, using a syringe and a needle. The advantage with the SAF system is that the irrigation fluid is continuously replenished throughout the procedure, thereby constantly providing a flow of fresh irrigating solution. In addition, in contrast to other file systems, the irrigant at the apical part of the root canal is relatively more effectively replaced by SAF because of the vibrating motion of the file's delicate mesh within the fluid.[15]

The combination of SAF system and GCE was observed to provide better smear layer-removing efficacy in contrast to the other groups.

Chamomile is comprised chemically of compounds known as “chamazolene” and “alpha-bisabolol.” It also contains acids such as capric acid, o-coumaric acid, p-coumaric acid, dihdroxybenzoic acid, and caprylic acid. The chelating effect of these mild acids may be responsible for their positive effect on smear layer removal.[13]

The effective smear layer removal by GCE is in accordance with the results of the previous study,[13],[14],[15] showing adequate smear layer removal.

It may be noted that 6% GCE showed relatively less effective smear layer removal capacity when used in conjunction with the WO file system. This could be attributed to the fact that the WO file system has an incomplete action in removal of dentinal debris and it may create a packed and less soluble smear layer which cannot be easily dissolved. In addition, it maybe stated that “Reciprocating” instruments produce a higher quantity of smear layer in comparison to other file systems used in a previous study.[13]

It may be noted that the removal of smear layer by intracanal irrigants is generally more pronounced in the coronal and middle aspects of root canal in comparison to apical thirds.[1] The larger canal diameter in the coronal and middle thirds exposes the dentin to a higher volume of irrigant, thereby allowing a better flow of the solution and thus a more adequate removal of the smear layer.

MCJ has been advantageously used as an endodontic irrigant as it is a biocompatible antioxidant irrigant and has no adverse effects.[14]

In contrast to results obtained in a previous study,[14] in the present study, 6% MCJ was not found to have satisfactory smear layer removal properties. The minimal removal of smear layer observed with 6% MCJ may be attributed to acids such as caproic acid, ursolic acid, and caprylic acid, which may be responsible for its smear layer removal action.[8]

In addition, sodium hypochlorite was not used at any stage in the present study, as the study was not designed to duplicate the clinical process but rather to isolate a single component: smear layer removal ability.

Herbal alternatives have now been extensively researched over years for their antimicrobial efficacy and smear layer-removing actions along with their effect on the root canal dentin. With promising results, they might soon be used more extensively as a better and safer alternative to the conventional irrigants. The current study was designed to explore the possibilities of herbal irrigants to be used with different irrigating protocols (manual and automated) for smear layer eradication and, in the present study, the results obtained may add a new positive dimension for herbal irrigants to be used in vivo conditions.

Apart from their antimicrobial effects and superior biocompatibility, the herbal irrigant GCE being successful in the eradication of smear layer makes it a valuable alternative to be used for root canal irrigation protocols.


  Conclusions Top


  1. GCE 6% was effective in removal of smear layer, when used with either continuous or syringe and needle irrigation systems
  2. MCJ 6% was ineffective in removal of smear layer, with either irrigation method
  3. EDTA (17%), which served as a positive control, was highly effective in removal of smear layer, but caused excessive demineralization under the conditions of the present study. Nevertheless, excessive demineralization of the dentin was observed when continuous irrigation was used
  4. GCE 6% did not cause the excessive demineralization that was observed with 17% EDTA.


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Violich DR, Chandler NP. The smear layer in endodontics – A review. Int Endod J 2010;43:2-15.  Back to cited text no. 1
    
2.
Murray PE, Farber RM, Namerow KN, Kuttler S, Garcia-Godoy F. Evaluation of Morinda citrifolia as an endodontic irrigant. J Endod 2008;34:66-70.  Back to cited text no. 2
    
3.
Calt S, Serper A. Time-dependent effects of EDTA on dentin structures. J Endod 2002;28:17-9.  Back to cited text no. 3
    
4.
Sadr Lahijani MS, Raoof Kateb HR, Heady R, Yazdani D. The effect of German chamomile (Matricaria recutita L.) extract and tea tree (Melaleuca alternifolia L.) oil used as irrigants on removal of smear layer: A scanning electron microscopy study. Int Endod J 2006;39:190-5.  Back to cited text no. 4
    
5.
Blanco YC, Vaillant F, Perez AM, Reynes M, Brillouet JM, Brat P. The noni fruit (Morinda citrifolia L.): A review of agricultural research, nutritional and therapeutic properties. J Food Composition Anal 2006;19:645-54.  Back to cited text no. 5
    
6.
Hammer KA, Dry L, Johnson M, Michalak EM, Carson CF, Riley TV, et al. Susceptibility of oral bacteria to Melaleuca alternifolia (tea tree) oil in vitro. Oral Microbiol Immunol 2003;18:389-92.  Back to cited text no. 6
    
7.
Martins HM, Martins ML, Dias MI, Bernardo F. Evaluation of microbiological quality of medicinal plants used in natural infusions. Int J Food Microbiol 2001;68:149-53.  Back to cited text no. 7
    
8.
Safayhi H, Sabieraj J, Sailer ER, Ammon HP. Chamazulene: An antioxidant-type inhibitor of leukotriene B4 formation. Planta Med 1994;60:410-3.  Back to cited text no. 8
    
9.
Wang MY, Su C. Cancer preventive effect of Morinda citrifolia (Noni). Ann N Y Acad Sci 2001;952:161-8.  Back to cited text no. 9
    
10.
Saghiri MA, Godoy FG, Asgar K, Lotfid M. The effect of Morinda citrifolia juice as an endodontic irrigant on smear layer and microhardness of root canal dentin. Oral Sci Int 2013;10:53-7.  Back to cited text no. 10
    
11.
Soukoulis S, Hirsch R. The effects of a tea tree oil-containing gel on plaque and chronic gingivitis. Aust Dent J 2004;49:78-83.  Back to cited text no. 11
    
12.
Madison JG 3rd, Hokett SD. The effects of different tetracyclines on the dentin root surface of instrumented, periodontally involved human teeth: A comparative scanning electron microscope study. J Periodontol 1997;68:739-45.  Back to cited text no. 12
    
13.
Poggio C, Dagna A, Chiesa M, Scribante A, Beltrami R, Colombo M, et al. Effects of Ni-Ti rotary and reciprocating instruments on debris and smear layer scores: An SEM evaluation. J Appl Biomater Funct Mater 2014;12:256-62.  Back to cited text no. 13
    
14.
Dubey S, Saha SG, Rajkumar B, Dhole TK. Comparative antimicrobial efficacy of selected root canal irrigants on commonly isolated microorganisms in endodontic infection. Eur J Dent 2017;11:12-6.  Back to cited text no. 14
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15.
Tubaro A, Zilli C, Redaelli C, Della Loggia R. Evaluation of antiinfl ammatory activity of a chamomile extract topical application. Planta Med 1984;50:359.  Back to cited text no. 15
    


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