: 2017  |  Volume : 29  |  Issue : 1  |  Page : 35--38

Smear layer removal efficacy of herbal extracts used as endodontic irrigants: An in vitro study

MA Sebatni, AA Kumar 
 Department of Conservative Dentistry and Endodontics, Rajas Dental College and Hospital, Tirunelveli, Tamil Nadu, India

Correspondence Address:
A A Kumar
5A/3, Ashirwad, Kesari Street, Nagercoil - 629 001, Kanyakumari, Tamil Nadu


Aim: This study aimed to evaluate the smear layer removal efficacy of various herbal extracts, namely, green tea extract, orange oil, and neem leaf extract using the scanning electron microscopic analysis. Materials and Methods: The samples were divided into four groups having ten teeth each (n = 10); the groups were divided accordingly, Group A: sodium hypochlorite (control), Group B: green tea extract, Group C: orange oil, and Group D: neem leaf extract. Each tooth was then split longitudinally and was prepared for examination by scanning electron microscope under ×1500 and ×3000. Statistical Analysis: The smear layer removal scores were compared statistically within the groups using analysis of variance and Tukey's honest significant difference test (P < 0.05). Results: The canals treated with neem leaf extract exhibited significant smear layer removal when compared to those treated with orange oil, sodium hypochlorite, and green tea extract. Conclusion: The highest amount of smear layer removal efficacy was seen in the canals treated by neem leaf extract.

How to cite this article:
Sebatni M A, Kumar A A. Smear layer removal efficacy of herbal extracts used as endodontic irrigants: An in vitro study.Endodontology 2017;29:35-38

How to cite this URL:
Sebatni M A, Kumar A A. Smear layer removal efficacy of herbal extracts used as endodontic irrigants: An in vitro study. Endodontology [serial online] 2017 [cited 2022 Jan 28 ];29:35-38
Available from: https://www.endodontologyonweb.org/text.asp?2017/29/1/35/207002

Full Text


Root canal therapy is aimed to completely eradicate microbes and three dimensionally seal the endodontic system. Chemo-mechanical debridement of the root canal system is the most accepted method to achieve complete disinfection. Mechanical preparation inadvertently forms an amorphous layer termed as the “smear layer” that may be embedded with debris and microorganisms.[1]

Elimination of the smear layer from the root canal walls is highly desirable to achieve long-term endodontic success. In this aspect, irrigating solutions play a significant role in the eradication of smear layer.[1]

Many chelating agents such as ethylenediaminetetraacetic acid, citric acid, and maleic acid have been used for the removal of smear layer. However, the disadvantages which have commonly been experienced while using these chemical formulations are decrease in dentin microhardness, dentinal erosions, allergic reactions, and biocompatibility problems.[2],[3],[4]

Synthetic irrigating solutions such as sodium hypochlorite have been associated with many adverse effects which have led many researchers to explore more biocompatible natural agents, of which herbal extracts are gaining significant prominence as endodontic irrigants. Hence, the aim of this study was to evaluate the smear layer removal efficacy of various herbal extracts used as endodontic irrigants.[2],[5],[6]

 Materials and Methods

Preparation of the herbal extracts

For the preparation of green tea extract, green tea powder was weighed (15 g), mixed with distilled water (150 ml), and boiled at 100°C to get 15 ml of green tea extract. For the preparation of orange oil, orange peel powder was weighed (15 g), mixed with distilled water (150 ml), and boiled at 100°C to get 15 ml of orange oil. For the preparation of neem leaf extract, neem leaf powder was weighed (15 g), mixed with distilled water (150 ml), and boiled at 100°C to get 15 ml of neem leaf extract. The prepared solutions were filtered using Whatman filter paper, and the final irrigating solutions were obtained and stored in opaque bottles.

Specimen preparation

Forty (n = 40) intact single-rooted human permanent teeth (n = 40) having a single canal and fully developed apices, indicated for extraction due to orthodontic/periodontal reasons, were selected for this study. The teeth were then cleaned using an ultrasonic scaler followed by sterilization with autoclave. The teeth were then stored in distilled water until use. The working length was measured radiographically to be 1 mm short of the apical foramen. The glide path was established using a size 15 K-file (Mani Inc., Japan). All the samples were then randomly divided into four groups with each group having ten samples.

The root canals were then prepared up to apical size 25, 0.06 taper using Rotary Protaper nickel–titanium files (Dentsply Tulsa), at specific speed and torque by manufacturer's instructions using the crown down preparation method. During the instrumentation, the canals were irrigated using 5 ml of the prepared solution corresponding to the respective group. In all the groups, the study specimens were finally rinsed with sterile distilled water and dried using sterile absorbent paper points (DiaDent Group International). The samples were then stored at humidity.

Thereafter, the teeth were decoronated at the cementoenamel junction using the diamond disc to obtain standardized root length of 10 mm [Figure 1]a. One longitudinal groove was placed on the buccal and lingual surfaces of each root using the diamond disc, avoiding penetration into the canal. The roots were then split into two halves using a chisel and mallet [Figure 1]b and were then coded as A1, A2, and A3 according to respective groups.{Figure 1}

Scanning electron microscopic evaluation

The coded specimens were then mounted onto metallic stubs with carbon strip backing and then subsequently viewed under the scanning electron microscope (SEM) [Figure 2]a and [Figure 2]b. After general evaluation of the canal wall, SEM photomicrographs were taken at magnification of ×1500 for evaluation of smear layer removal of each specimen [Figure 3]. Smear layer removal was then evaluated using the scoring system given by Rome et al. (1985) [Table 1].{Figure 2}{Figure 3}{Table 1}

Statistical analysis

The collected data were subjected to one-way analysis of variance to compare the means of the groups. The Tukey's post hoc test was performed for the intergroup mean comparison between the groups. The data were considered to be statistically significant when P < 0.05.


The mean of the smear layer removal scores was calculated for all the four groups. On intergroup comparison, Group IV showed the best outcome and exhibited statistically significant difference from other groups except Group III (P) [Table 2]a. There was statistically significant difference in smear layer removal efficacy among all the other groups [Table 2]b and [Figure 4].{Table 2}{Figure 4}


Smear layer comprises both of organic and inorganic phases which has to be removed by an ideal smear layer-removing agent without erosive effects on dentin. Smear layer removal from canal walls is of much importance because this opens up the dentinal tubules, thus allows penetration of irrigants into tubules.[1] The efficacy of intracanal medicaments and irrigants gets increased by the removal of smear layer, and the time needed for canal disinfection also gets reduced. It further facilitates the adaptation of root canal filling to canal walls and reduction in apical leakage.[1]

Scanning electron microscopy, which can detect accurate surface characteristics, was used to assess the effectiveness of various irrigants in the removal of smear layer.[3],[4]

To overcome the undesirable effects of NaOCl, three herbal extracts were selected to disinfect the root canal system.[6] Green tea extract has major constituents of catechins (polyphenols) which has greater activity against a wide spectrum of microbes and also found to be a good chelating agent. Orange oil is composed mainly of d-limonene. Neem leaf extract with its antioxidant and antimicrobial properties has been proved to be effective against Enterococcus faecalis and Candida albicans which makes it a potential agent for root canal irrigation.[2]

In the present study, Group II (green tea extract) exhibited the least amount of smear layer removal efficacy which might be due to the absence of acid metabolites which is needed for the removal.[6]

Whereas Group I (NaOCl) has the ability to remove only the organic residues, hence results in lesser amount of smear layer.[7]

Group III (orange oil) and Group IV (neem leaf extract) due to the presence of acid metabolites, flavanoids, exhibited the highest amount of smear layer removal efficacy compared to all the other groups in the present study.[8]


Herbal alternatives are easy available, cost-effective, increased shelf-life, low toxicity, and lack of microbial resistance. The in vitro observations of herbal products appear promising, but preclinical and clinical trials are needed to evaluate the biocompatibility and safety factor before they can conclusively be recommended as intracanal irrigating solutions and medicaments.

Hence, herbs can be used for treatment procedures that have been established to be effective and with minimal risk involved.


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