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ORIGINAL ARTICLE
Year : 2020  |  Volume : 23  |  Issue : 3  |  Page : 381-385

Effect of various solutions on the removal of orange-brown precipitate formed by interaction of sodium hypochlorite and chlorhexidine with or without ultrasonic activationZ


Department of Endodontics, Faculty of Dentistry, Hacettepe University, Ankara, Turkey

Date of Submission30-Sep-2019
Date of Acceptance13-Dec-2019
Date of Web Publication5-Mar-2020

Correspondence Address:
Dr. A Keles
Department of Endodontics, Faculty of Dentistry, Hacettepe, University, Ankara
Turkey
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njcp.njcp_527_19

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   Abstract 


Objectives: This study aimed to compare the effect of different solutions on the removal of orange-brown precipitate with or without ultrasonic activation. Materials and Methods: One hundred and twenty extracted maxillary anterior teeth were instrumented. In experimental groups (n = 10), canals were flushed with 17% EDTA, 10% citric acid, 1% phytic acid, 96% alcohol and distilled water either using syringe irrigation or ultrasonic activation, after creating orange-brown precipitate. Teeth were sectioned longitudinally and subjected to stereomicroscopic analysis. The amount of precipitate was scored and the data were analyzed (P = 0.05). Results: There were no differences detected among the tested solutions (P > 0.05). There was a significant difference between ultrasonically activated irrigation and syringe irrigation for EDTA and distilled water in coronal, middle portions (P < 0.05). Conclusions: Ultrasonic activation significantly improved the precipitate removal capacity of EDTA and DW. Tested solutions were similarly effective regarding the removal of the precipitate.

Keywords: Chlorhexidine, endodontics, irrigant interactions, root canal preparation, root canal therapy, sodium hypochlorite


How to cite this article:
Keles A, Ors S A, Yilmaz Z. Effect of various solutions on the removal of orange-brown precipitate formed by interaction of sodium hypochlorite and chlorhexidine with or without ultrasonic activationZ. Niger J Clin Pract 2020;23:381-5

How to cite this URL:
Keles A, Ors S A, Yilmaz Z. Effect of various solutions on the removal of orange-brown precipitate formed by interaction of sodium hypochlorite and chlorhexidine with or without ultrasonic activationZ. Niger J Clin Pract [serial online] 2020 [cited 2020 Apr 6];23:381-5. Available from: http://www.njcponline.com/text.asp?2020/23/3/381/280037




   Introduction Top


During the root canal treatment, mechanical instrumentation alone may not be adequate to reduce the bacteria, which are the main cause of root canal infections.[1] Hence, mechanical instrumentation in conjunction with irrigation solutions has a dispensable role in terms of eliminating bacteria.[2]

Sodium hypochlorite (NaOCl) is the most commonly used irrigant in endodontics because of its high antimicrobial and tissue dissolving features.[3] However, NaOCl is highly cytotoxic and does not provide any antimicrobial substantivity.[4] On the other hand, chlorhexidine (CHX) is another alternative irrigant that has low cytotoxicity, broad antimicrobial spectrum, and antimicrobial substantivity to dentin, but contrary to NaOCl, has no tissue dissolution capacity.[3]

It has been reported that the antimicrobial effects of NaOCl and CHX are enhanced when used in conjunction.[5] However, the interaction of NaOCl and CHX causes dense, orange-brown precipitate.[6],[7] The biologic and chemical nature of the precipitate is vastly investigated.[7],[8],[9],[10],[11],[12] Still, whether it contains para-chloroaniline (PCA) or not remains a contradictory question.[7],[8],[9],[10],[11],[12] Regardless of its chemical components, the precipitate may occlude dentinal tubules, hence it may affect the sealing ability of sealers and may also cause discoloration.[6],[13] Furthermore, the precipitate may have some cytotoxic effects on human tissues.[14]

Different solutions such as citric acid (CA), isopropyl alcohol, saline, distilled water (DW), and ethylenediaminetetraacetic acid (EDTA) have been investigated for removal[15],[16] or prevention[17],[18],[19] of the precipitate. Phytic acid (inositol hexaphosphate, IP6) is a recently investigated solution claimed to be an alternative to EDTA, due to its less cytotoxicity, similar smear layer, and intracanal medicament removal efficiency.[20],[21] Its potential on the removal/prevention of the orange-brown precipitate is unknown.

In addition to the solution itself, irrigant activation systems may also enhance the removal or prevention of the precipitate. It has been reported that ultrasonically activated irrigation (UAI) was more effective regarding the removal of debris and intracanal medicaments compared to conventional syringe irrigation (SI).[22],[23]

The previous studies mainly concentrated on the prevention of the orange-brown precipitate.[17],[18],[19] However, there are limited studies regarding the removal of the precipitate in case of inadvertent formation.[15],[16] Therefore, the aim of this study was to investigate the effect of UAI and different solutions on the removal of orange-brown precipitate. Therefore, the first null hypothesis was that different solutions have no significant effect on the removal of the orange-brown precipitate, and the second null hypothesis was that UAI has no significant effect on the removal of the precipitate.


   Materials and Methods Top


One hundred and twenty extracted maxillary anterior teeth with similar buccolingual and mesio-distal dimensions and single root canals were selected for this study after Ethics Committee approval was granted from University's Ethics Comittee (GO 17/672-34). Teeth with incomplete root formation, caries, crack lines, and fractures were excluded. Before the experiment, the teeth were decontaminated from soft and hard tissue residues and were stored in distilled water until usage.

The coronal portions of the teeth were removed using a high-speed disc to obtain a standardized length of 16 mm. The working length was set as 15 mm. All of the teeth were embedded into the wax to prevent irrigant extrusion and enhance handling. The root canals were instrumented up to F4 (#0.40, taper 0.06) (Dentsply Maillefer, Ballaigues, Switzerland) and were irrigated with 1 ml of 5% NaOCl (Werax, Izmir, Turkey) between each file. Final irrigation was performed with 2.5 ml 17% EDTA for 1 min (Werax, Izmir, Turkiye). 10 samples were reserved for negative control group. To simulate the accidental formation of orange-brown precipitate, the remaining 110 root canals were irrigated with 5 ml 5% NaOCl for 1 min. While flooded with NaOCl, root canals immediately irrigated with 5 ml 2% CHX (Werax, Izmir, Turkey) for 1 min. Subsequently, another 10 samples were reserved to represent positive control group. The remaining 100 samples were randomly divided into two main groups (n = 50) according to the presence of ultrasonic activation and 5 subgroups according to the type of irrigation solution (n = 10).

Precipitate removal procedures

Group 1- Syringe Irrigation Group

The root canals were flushed with different solutions stated below:

Group 1a- 17% EDTA,

Group 1b- 96% ethyl alcohol (EA),

Group 1c- 1% phytic acid (IP6),

Group 1d- 10% citric acid (CA),

Group 1e- Distilled water (DW).

In each subgroup, a 6 ml solution used with 27-G needle which placed 2 mm short of the working length and moved in a 3-mm up and down motion for 120 s to remove the orange precipitate.

Group 2- Intermittent Ultrasonic Activation[24] Group

The root canals were flushed with different solutions stated below:

Group 2a- 17% EDTA,

Group 2b- 96% ethyl alcohol (EA),

Group 2c- 1% phytic acid (IP6),

Group 2d- 10% citric acid (CA),

Group 2e- Distilled water (DW).

In these subgroups, 6 ml of the irrigation solution was delivered in three cycles each 40 s as follows: 20 s of ultrasonic activation and 20 s of 2 ml syringe irrigation. During ultrasonic activation, 21 mm, Ni-Ti, non-cutting wire (#0.20, taper 0.02) (EndoUltra, Micro Mega, Besançon, France) was attached to the ultrasonic unit (EndoUltra, Micro Mega, Besançon, France) and was activated at 1 mm short of the WL.

After the removal procedures, the surrounding wax was removed. The coronal and apical portions of the root canals were sealed using putty impression material (Optosil Comfort Putty, Heraeus Kulzer, Dormagen, Germany). Two vertical grooves on the buccal and lingual surfaces of the samples were prepared without invading root canal. Then, roots were split longitudinally into two halves using a chisel. All of the root halves were photographed using a stereomicroscope (Nikon SMZ 1000; Nikon, Tokyo, Japan) at 15 × magnification. The acquired images were examined on the computer. The root halves were marked to separate apical, middle, and coronal thirds. Three calibrated independent observers scored the amount of orange-brown precipitate in each third. Scores indicated the following features:[13]

Score 0. There was no orange-brown precipitate on the root canal;

Score 1. Orange-brown precipitate was present but less than half of the root canal;

Score 2. More than half of the root canal was covered with orange-brown precipitate;

Score 3. The root canal was completely covered with orange-brown precipitate [Figure 1].
Figure 1: (a) Score 0, (b) Score 1, (c) Score 2, (d) Score 3

Click here to view


Interexaminer agreement was evaluated using the Kappa test. The data were analyzed using Kruskal–Wallis and Mann–Whitney tests at a 95% confidence level (P = 0.05). The statistical analyses were performed using SPSS version 20 software (IBM SPSS Inc., Chicago, IL, USA).


   Results Top


Interexaminer reliability value was high and the difference between the matched scores never exceeded one unit (Kappa value = 0.9483). The Kruskal–Wallis test demonstrated significant differences between the tested solutions and control groups both in Group 1 (SI) and Group 2 (UAI) [Figure 2].
Figure 2: Percentages of the scores according to the solutions and irrigation delivery method

Click here to view


Group 1 (SI):

In all thirds of SI group, there were no significant differences among the tested solutions (P > 0.05). Considering the differences between tested solutions and control groups, in the coronal portion of SI groups, all tested solutions were significantly different than positive control group except EDTA (P < 0.05). In the middle portion of SI group, while EDTA showed higher scores than negative control (P < 0.05), all solutions presented lower orange-brown precipitate scores than positive control (P < 0.05). In the apical portion, there was no difference between any of the solutions and negative control group (P > 0.05), while all of the solutions were significantly different from positive control group (P < 0.05).

Group 2:

In all portions of the activation group, there was no significant difference between any of the solutions and negative control group (P > 0.05), while all of the solutions were significantly cleaner than positive control group (P < 0.05).

Regardless of the irrigation type (SI or UAI), in all groups, there was no significant difference between apical and middle portions of the canals (P > 0.05), which were significantly cleaner than the coronal portion (P < 0.05).

There was a significant difference between Group 1 compared to Group 2 for EDTA and DW in the coronal and middle portion of the root canal. UAI significantly improved precipitate removal capacity of EDTA and DW (P < 0.05).


   Discussion Top


It is well known that the interaction of NaOCl with CHX causes an orange-brown precipitate.[6],[7] However, the chemical components of the precipitate remain unclear. Several studies stated that the formed precipitate contains PCA,[7],[8],[11] but some other studies reported contrary results.[9],[10],[12] Various analysis methods such as proton nuclear magnetic resonancespectroscopy (1 H-NMR),[9],[12],[13] infrared spectroscopy (IR),[10] time of flight secondary ion mass spectrometry (TOF-SIMS),[7],[11] gas chromatography (GC)/mass spectrometry (MS),[8],[10],[19] and X-Ray photoelectron spectroscopy (XPS)[7] were utilized to detect PCA component in the formed precipitate. Eventually, a novel study[12] evaluated the precipitate with various methods including the abovementioned ones and stated that no PCA could be detected in the precipitate. Krishnamurthy and Sudhakaran[17] evaluated the effect of various solutions on the prevention of the precipitate. Beilstein and HCl solubility tests, and nuclear magnetic resonance imaging technique were applied as confirmation methods after stereomicroscopic analysis to detect the presence of the PCA in the precipitate. However, these tests do not identify the exact interaction product.[9] Mortenson et al.[19] investigated the prevention of the PCA in the root canal system using different solutions between NaOCl and CHX. Researchers used gas chromatography/mass spectrometry tests for analyzing the PCA formed in the root canal system by extracting it from the root canal through dichloromethane solution. Extracting the precipitate from root canal system may not be a reliable method. In addition, due to the contradictions regarding the presence of the PCA in the precipitate, the present study utilized stereomicroscope images[13],[15],[16],[25] to evaluate the removal of the precipitate rather than chemical analysis of the presence of PCA.

In order to facilitate transportation of the solutions to the apical region and ease the longitudinal splitting of the roots, maxillary anterior teeth were selected in this study due to their larger canal anatomy.

In addition, mechanical preparation was done up to Protaper F4 in order to enhance penetration of the solutions to the apical area.

In this study, there were no significant differences among tested solutions; thus, the first null hypothesis was accepted. It is well known that UAI is more effective than conventional syringe irrigation in terms of removal of debris or medicaments.[22],[23] In the present study, UAI increased the precipitate removal capacity of EDTA on the coronal and middle portions, which were significantly different than negative control in the syringe irrigation group. These groups became statistically similar to the negative control in the UAI group. UAI also increased the precipitate removal capacity of DW on the coronal and middle portion. DW was significantly different than negative control in the coronal portion and became statistically similar in UAI group. Ultrasonic activation did not affect other solutions, which were already statistically similar to the negative control. Therefore, these solutions were already effective without ultrasonic activation regarding precipitate removal. Therefore, the second null hypothesis was also partially accepted.

In medicament and debris removal studies, generally coronal portions of the root canals presented significantly cleaner images than middle and apical portions after the removal procedures.[23] These findings may be attributed to the difficulty of irrigation solution to reach the apical area. In the present study, apical and middle portions were significantly cleaner than coronal portions. In the same vein, the reason that apical and middle portions were significantly cleaner may be due to decreased amount of delivered solution, hence, less interaction and less precipitate.

Within the limitations of this study, solutions were found to be similarly effective in terms of removal of the precipitate. There was no significant difference between solutions and negative control in the SI group except EDTA and DW in the coronal portion and EDTA in the middle portion. Ultrasonic activation significantly improved the precipitate removal capacity of EDTA and DW.

Financial support and sponsorship

This study was supported by the Scientific Research Projects Coordination Unit of Hacettepe University (THD-2018-16071).

Conflicts of interest

There is no conflict of interest



 
   References Top

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Basrani BR, Manek S, Sodhi RN, Fillery E, Manzur A. Interaction between sodium hypochlorite and chlorhexidine gluconate. J Endod 2007;33:966-9.  Back to cited text no. 7
    
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Basrani BR, Manek S, Mathers D, Fillery E, Sodhi RN. Determination of 4-chloroaniline and its derivatives formed in the interaction of sodium hypochlorite and chlorhexidine by using gas chromatography. J Endod 2010;36:312-4.  Back to cited text no. 8
    
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Nowicki JB, Sem DS. An in vitro spectroscopic analysis to determine the chemical composition of the precipitate formed by mixing sodium hypochlorite and chlorhexidine. J Endod 2011;37:983-8.  Back to cited text no. 9
    
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Orhan EO, Irmak O, Hur D, Yaman BC, Karabucak B. Does para-chloroaniline really form after mixing sodium hypochlorite and chlorhexidine? J Endod 2016;42:455-9.  Back to cited text no. 10
    
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Kolosowski KP, Sodhi RN, Kishen A, Basrani BR. Qualitative analysis of precipitate formation on the surface and in the tubules of dentin irrigated with sodium hypochlorite and a final rinse of chlorhexidine or QMiX. J Endod 2014;40:2036-40.  Back to cited text no. 11
    
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Thomas JE, Sem DS. An in vitro spectroscopic analysis to determine whether para-chloroaniline is produced from mixing sodium hypochlorite and chlorhexidine. J Endod 2010;36:315-7.  Back to cited text no. 12
    
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Arslan H, Uygun AD, Keskin A, Karatas E, Seckin F, Yildirim A. Evaluation of orange-brown precipitate formed in root canals after irrigation with chlorhexidine and QMix and spectroscopic analysis of precipitates produced by a mixture of chlorhexidine/NaOCl and QMix/NaOCl. Int Endod J 2015;48:1199-203.  Back to cited text no. 13
    
14.
Chhabra RS, Huff JE, Haseman JK, Elwell MR, Peters AC. Carcinogenicity of p-chloroaniline in rats and mice. Food Chem Toxicol 1991;29:119-24.  Back to cited text no. 14
    
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Guneser MB, Dincer AN, Arslan D. Comparison of conventional syringe, canalbrush, endoactivator, photon-induced photoacoustic streaming, and manual instrumentation in removing orange-brown precipitate: An in vitro study. Photomed Laser Surg 2017;35:311-6.  Back to cited text no. 15
    
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Krishnamurthy S, Sudhakaran S. Evaluation and prevention of the precipitate formed on interaction between sodium hypochlorite and chlorhexidine. J Endod 2010;36:1154-7.  Back to cited text no. 17
    
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Magro MG, Kuga MC, Aranda-Garcia AJ, Victorino KR, Chávez-Andrade GM, Faria G, et al. Effectiveness of several solutions to prevent the formation of precipitate due to the interaction between sodium hypochlorite and chlorhexidine and its effect on bond strength of an epoxy-based sealer. Int Endod J 2015;48:478-83.  Back to cited text no. 18
    
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Ma JZ, Shen Y, Al-Ashaw AJ, Khaleel HY, Yang Y, Wang ZJ, et al. Micro-computed tomography evaluation of the removal of calcium hydroxide medicament from C-shaped root canals of mandibular second molars. Int Endod J 2015;48:333-41.  Back to cited text no. 23
    
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van der Sluis LW, Vogels MP, Verhaagen B, Macedo R, Wesselink PR. Study on the influence of refreshment/activation cycles and irrigants on mechanical cleaning efficiency during ultrasonic activation of the irrigant. J Endod 2010;36:737-40.  Back to cited text no. 24
    
25.
Arslan H, Gok T, Saygili G, Altintop H, Akcay M, Capar ID. Evaluation of effectiveness of various irrigating solutions on removal of calcium hydroxide mixed with 2% chlorhexidine gel and detection of orange-brown precipitate after removal. J Endod 2014;40:1820-3.  Back to cited text no. 25
    


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