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Year : 2015  |  Volume : 5  |  Issue : 2  |  Page : 65-70

Comparison of different irrigating solutions on root canal disinfection after mechanical preparation by using scanning electron microscope: An in vitro study

1 Department of Conservative Dentistry and Endodontics Sawangi, Datta Meghe Institute of Medical Sciences, Sharad Pawar Dental College, Wardha, Maharashtra, India
2 Department of Conservative and Endodontics, Datta Meghe Institute of Medical Sciences, Sharad Pawar Dental College, Sawangi Meghe, Wardha, Maharashtra, India

Date of Web Publication5-Jan-2016

Correspondence Address:
Abhilasha Dass
Department of Conservative and Endodontics, Datta Meghe Institute of Medical Sciences, Sharad Pawar Dental College, Sawangi Meghe, Wardha, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2229-5194.173225

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Objectives: The aim of this in vitro study was to compare the efficacy of different irrigating solutions on root canal system and analyzing smear layer using scanning electron microscope (SEM). Materials and Methods: Fifty mandibular premolars were decoronated and split longitudinally. Each root half was divided into five groups (n = 10): Group I - 3 ml of physiological saline, Group II - 3 ml of 2.5% sodium hypochlorite (NaOCl), Group III - 1 ml of 10% citric acid, Group IV - 2% chlorhexidine (CHX) gluconate (Vishal Dentocare, India), Group V - Largal Ultra (ethylenediaminetetraacetic acid [EDTA] 15% + cetrimide 0.75%), Septodont (Saint-Maur-des-fosses, France), and Group VI - Smear Clear (Sybron Endo, Orange, CA, USA) (17% EDTA, cetrimide, and a special surfactant). Irrigation regimens were performed for 1 min. The presence or absence of smear layer at the coronal, middle, and apical portion of each canal were examined under an SEM. Results: A significant difference (P < 0.001) in smear layer removal between smear clear and Largal Ultra at the apical and middle third of the canal was observed. The presence of debris is more obvious in the apical third rather than in the middle and coronal part of the root canals. Conclusion: Largal Ultra, Smear Clear, and the citric acid removed the smear layer more efficient way as compared to CHX, NaOCl, and saline solutions.

Keywords: Irrigation, scanning electron microscope, smear clear

How to cite this article:
Salgar A, Chandak M, Dass A, Saxena A, Bhatia C, Chandak R. Comparison of different irrigating solutions on root canal disinfection after mechanical preparation by using scanning electron microscope: An in vitro study. J Interdiscip Dentistry 2015;5:65-70

How to cite this URL:
Salgar A, Chandak M, Dass A, Saxena A, Bhatia C, Chandak R. Comparison of different irrigating solutions on root canal disinfection after mechanical preparation by using scanning electron microscope: An in vitro study. J Interdiscip Dentistry [serial online] 2015 [cited 2023 Jun 3];5:65-70. Available from: https://www.jidonline.com/text.asp?2015/5/2/65/173225

   Introduction Top

The success of root canal therapy is dependent on mechanical preparation, irrigation, microbial control, and complete obturation of root canals. Elimination of microorganisms from infected root canals is a complicated task. The chances of a favorable outcome with root canal treatment are significantly higher if infection is eradicated effectively before the root canal system is obturated. However, if microorganisms persist at the time of obturation or if they penetrate into the canal after obturation, there is a high risk of treatment failure.[1],[2] Irrigation is an essential part of root canal debridement because it allows for cleaning beyond what might be achieved by root canal instrumentation alone.[3],[4] However, there is no one unique irrigant that can meet all these requirements, even with the use of methods such as lowering the pH,[5],[6],[7] increasing the temperature,[8],[9] as well as the addition of surfactants to increase the wetting efficacy of the irrigant.[10],[11] Thus, in contemporary endodontic practice, dual irrigants such as sodium hypochlorite (NaOCl) with ethylenediaminetetraacetic acid (EDTA) or chlorhexidine (CHX)[12],[13],[14] are often used as initial and final rinses to complement the shortcomings that are associated with the use of a single irrigant. Another issue of great importance during root canal treatment is the smear layer. Some authors suggest that keeping the smear layer may block the dentinal tubules and limit bacterial or toxin penetration by altering the dentinal permeability.[15],[16],[17] Some authors believe that the smear layer must be completely removed from the surface of the canal wall because it can harbor bacteria and can be detrimental to the effective disinfection of dentinal tubules by preventing irrigant and medicaments from penetrating into the dentinal tubules.

In this study, an evaluation was made by scanning electronic microscopy (SEM) of the capacity of NaOCl, CHX, citric acid, smear clear (Sybron Endo, Orange, CA, USA) (17% EDTA, Cetrimide, and a special surfactant) and Largal Ultra (EDTA 15% + cetrimide 0.75%), (Septodont, Saint-Maur-des-fosses), France, to remove the smear layer from the root canal. The amount of calcium ions removed from the root canal by these solutions was also analyzed by atomic absorption spectrometry.

   Materials and Methods Top

Sample preparation

Fifty recently extracted human mandibular premolar teeth with completely formed roots, which had a single canal and the absence of calcifications or accentuated curvatures, were selected.

Each tooth was accessed coronally with Endo Access Bur, and all the teeth were decoronated at the cementoenamel junction using diamond disc (KG Sorensen, Brazil). After this procedure, the cervical preparation of each specimen was performed with LA Axxess 20/06, 35/06, and 45/06 burs (Sybron Endo Corporation, West Collins, Orange, CA, USA). Teeth were instrumented by crown-down technique using rotary Protaper Universal (Dentsply Maillefer, Switzerland) system till file size F2. At every change of instrument, the canals were irrigated with 2 ml of 2.5% NaOCl solutions during procedure. After Instrumentation, five subgroups were made and each had ten teeth each and different irrigation protocols were used in each group.

Group I

The canals were irrigated using 3 ml of physiological saline only for 1 min.

Group II

The canals were irrigated using 3 ml of 2.5% NaOCl for 1 min only.

Group III

The canals were irrigated with 1 ml of 10% citric acid for 1 min followed by 3 ml of 2.5% NaOCl solution. Citric acid was allowed to remain in the canal for 1 min only.

Group IV

The canals were irrigated with 2% CHX gluconate (Vishal dentocare, India) for 1 min followed by 3 ml of 2.5% NaOCl solution. CHX was allowed to remain in the canal for 1 min only.

Group V

The canals were irrigated with Largal Ultra (EDTA 15% + cetrimide 0.75%), Septodont, Saint-Maur-des-fosses, France, for 1 min followed by 3 ml of 2.5% NaOCl solution. Largal Ultra was allowed to remain in the canal for 1 min only.

Group VI

The canals were irrigated with Smear Clear (Sybron Endo, Orange, CA, USA) (17% EDTA, cetrimide, and a special surfactant) for 1 min followed by 3 ml of 2.5% NaOCl solution. Smear Clear was allowed to remain in the canal for 1 min only.

The time of instrumentation with each file was 60 s. After instrumentation, all the root canals were irrigated with 2 ml of one of the four irrigating solutions for 30 s followed, by a final flush with 5 ml of distilled water for 60 s. Canals were dried with paper points and markings were made in the root and divided into three equal halves: Coronal, middle, and apical. After which the roots were split longitudinally using a diamond disk on a low-speed handpiece in the buccolingual plane. The desiccated specimens were mounted for SEM and coated with carbon and gold in a discharge evaporator unit. The samples were studied under SEM at magnifications of (550 × and 1000× –15 kV) at the junction of the middle and apical areas of the wall. Two examiners who were blinded to specimen groups scored the SEM photomicrographs separately. Before the scoring proper, two examiners assessed the first 20 specimens together for calibration purposes. Intra- and inter-examiner's reliability was verified using the kappa test. The amount of debris and smear layer present was scored, and frequencies of the scores were subject to statistical evaluation using the Chi-square test. Smear layer and debris scoring is shown in [Table 1] and [Table 2].
Table 1: Score of the smear layer: Hulsmann et al.

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Table 2: Score of debris

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The cleaning ability of irrigating solutions was evaluated using the debris and smear layer score system introduced by Hulsmann et al.[29] These scoring systems were applied to the middle and apical areas of sample. The scoring criteria for smear layer removal were as in [Table 1] and [Table 2].

Statistical analysis

The data were analysed using one-way ANOVA test using SPSS 11.0 software (Economic and Statistical Division, MIcrosoft Corporation, Chicago). The intergroup and intragroup statistical differences were identified using Tukey test using (Graph Pad Prism 3.0; Graph Pad Software, Inc). P < 0.001 was considered significant.

   Results Top

There was no significant difference between Largal Ultra, citric acid, and Smear Clear groups regarding the remaining smear layer scores within the coronal and middle thirds of the root canals (P > 0.001). Largal Ultra, citric acid, and Smear Clear removed smear layer efficiently in the middle and apical thirds of the root canal [Figure 3],[Figure 5] and [Figure 6]. Specimens treated with NaOCl and saline showed a thick smear layer and smear plugs in middle and apical thirds of the root canal [Figure 1] and [Figure 2]. Specimens treated with CHX showed abundant smear layer and blocked dentinal tubules [Figure 4]. Pie chart showing statistically scores for the presence of debris in [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11]. [Table 3] and [Table 4] shows individual smear and debris score of all the groups. However, significant differences in smear layer among the six groups were observed (P>0.001) [Figure 12].
Figure 1: Group I analysis by scanning electron microscope

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Figure 2: Group II analysis by scanning electron microscope

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Figure 3: Group III analysis by scanning electron microscope

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Figure 4: Group IV analysis by scanning electron microscope

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Figure 5: Group V analysis by scanning electron microscope

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Figure 6: Group VI analysis by scanning electron microscope

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Figure 7: Group I and II

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Figure 8: Group III

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Figure 9: Group IV

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Figure 10: Group V

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Figure 11: Group VI

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Table 3: Comparison of smear layer (SEM) in all groups

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Table 4: Illustrates the mean and standard deviation of all the groups

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Figure 12: Intergroup comparison of root canal disinfection of various irrigants by Kruskal–Wallis test

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   Discussion Top

According to the results of this study, root canal debris and smear layer removed with different irrigating solutions seemed to vary. This finding may be because of the inability to deliver continuous intracanal irrigation throughout the procedure. In Group A (control group) and Group B, where normal physiological saline and 2.5% NaOCl, respectively, were used as an irrigants, the dentinal tubules were completely covered by the smear layer under SEM typical appearance of smear layer could be seen on root canal wall in apical third region. The findings were in agreement with the results of many other investigations done by Baumgartner and Cuenin [18] and Yamashita et al.[19]

The worldwide use of NaOCl as a root canal irrigating solution is due mainly to its efficacy for pulpal dissolution and antimicrobial activity. The saponification, amino acid neutralization, and chloramination reactions that occur in the presence of microorganisms and organic tissue lead to the antimicrobial and tissue dissolution process. It also acts as lubricant and thus plays a key role in successful debridement and disinfection.[20],[21] In Group V (Smear Clear), it was found that there was almost complete removal of smear layer in the apical third area under SEM. Smear Clear (SybronEndo, Orange, CA, USA) contains 17% EDTA solution with 2 additional proprietary surfactants, cetrimide (cetyltrimethylammonium bromide) is a quaternary ammonium salt and a cationic detergent added to many products because its addiction improves efficacy of irrigating solutions: Cationic surfactants have been reported to have bactericidal and fungicidal properties.[22]

Group III (10% citric acid) showed that even lower concentration of citric acid was also found to be effective in removing the smear layer and the results were similar to other studies Torabinejad et al.[23] and Smith and Wayman [24] and when 50% citric acid was used which may be attributed to the extremely high demineralization effect. This is in accordance with study findings of Baumgartner et al.[25] Group IV CHX is an effective antifungal agent and has antibacterial substantivity but it does not remove and dissolves debris and smear layer. It has been reported that smear layer removal is less predictable in the apical region as compared with the coronal and middle third of the root.[26],[27] This could be attributed to comparatively smaller apical canal dimensions hindering the penetration of irrigants and resulting in limited contact between canal walls and the irrigants.

The additives in Largal Ultra (EDTA 15% + cetrimide 0.75%), Septodont, (Saint-Maur-des-fosses, France), and Smear Clear (Sybron Endo, Orange, CA, USA) (17% EDTA, cetrimide and a special surfactant), decreases the viscosity and the surface tension. The formulation of Smear Clear contains a special surfactant which is claimed to reduce the contact angle of the EDTA solution when placed on dentin surface and enhanced cleaning efficacy. Group VI Largal Ultra which contains 15% EDTA and Smear Clear which has 17% of the same chelating agent and the results obtained from the two irrigants, however, were practically identical. They removed the smear layer, opened the dentinal tubules, and left only minimal debris.

Zehnder et al.[28] demonstrated that the use of chelators with wetting agents did not increase calcium removal from root canals.

The choice and use of the appropriate and most efficient irrigating agent however requires better understanding of their action. Moreover, smear layer removal is controversial and, certainly, not the only factor affecting root canal. Since in vitro conditions may not reflect the in vivo accurately, furtherstudies should be conducted to evaluate the accurateperformance of irrigation solutions for root canal treatment.

   Conclusion Top

Several irrigating solutions containing antimicrobials could not remove nor kill significantly biofilms developed on intra-orally infected dentin with the exception of NaOCl. Hence, to remove the smear layer a combination of irrigating solutions should be used. A chelating agent (EDTA) is recommended with combined use of NaOCl. The best removal of smear layer was observed with Largal Ultra, Smear Clear, and the citric acid. Hence, the present study was therefore done with the purpose of evaluating the effects of various root canal irrigants on smear layer and debris removal.

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Conflicts of interest

There are no conflicts of interest.

   References Top

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12]

  [Table 1], [Table 2], [Table 3], [Table 4]


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