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ORIGINAL ARTICLE
Year : 2022  |  Volume : 13  |  Issue : 2  |  Page : 41-48

Chemical changes in root canal dentin of primary teeth after endodontic irrigation: A Scanning Electron Microscopic and Energy-Dispersive X-ray Analysis


1 Department of Pediatric and Preventive Dentistry, Kannur Dental College, Kannur, Kerala, India
2 Department of Zoology, University of Calicut, Malappuram, Kerala, India

Date of Submission10-Jan-2022
Date of Decision07-May-2022
Date of Acceptance07-May-2022
Date of Web Publication20-Jun-2022

Correspondence Address:
Dr. Aparna T Purakkal
Department of Pedodontics and Preventive Dentistry, Kannur Dental College, Anjarakandy, Kannur - 670 612, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/srmjrds.srmjrds_1_22

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  Abstract 

Background: The current root canal irrigants used in dentistry are either antibacterial or decalcifying agents or their combinations. These agents can alter the chemical structure of dentin as well as change its permeability and solubility characteristics. Aim: The aim of this study was to evaluate the mineral content of root canal dentin after irrigating with five different endodontic irrigation solutions Materials and Methods: Sixty primary anterior teeth were selected for the study. Cleaning and shaping was done by step-back technique and divided randomly into six groups (n = 10): BioPure™ MTAD (Group 1), QMix™ 2-in-1 solution (Group 2), 0.9% normal saline (Group 3), coconut water (Group 4), and 5.25% NaOCl (Group 5) and the uninstrumented ten teeth were grouped as Group 6. After irrigation with final irrigants, the teeth were longitudinally divided into two halves. The levels of six elements calcium, phosphorus, oxygen, carbon, arsenic, and fluoride at the coronal and middle third in each specimen was assessed using scanning electron microscopy and energy-dispersive X-ray analysis. Statistical analysis was done by SPSS version 20 using one-way analysis of variance, and the comparison of means was conducted using post hoc Tukey test. Results: There was a statistically significant reduction in the calcium level at the coronal third of radicular dentin after irrigating with five different irrigants when compared with the uninstrumented teeth group. The phosphate level at the coronal third of the radicular dentin significantly increased in all the groups except for the saline group. The other elements such as oxygen, fluoride, and arsenic also showed significant differences in the coronal and middle levels after the irrigation. Conclusion: The endodontic irrigation by various irrigants changed the mineral levels in primary tooth dentin

Keywords: Endodontics, irrigating solutions, primary teeth, tooth minerals


How to cite this article:
Purakkal AT, Peedikayil FC, Vardhanan Y S, Chandru T P, Kottayi S, Melethil BY. Chemical changes in root canal dentin of primary teeth after endodontic irrigation: A Scanning Electron Microscopic and Energy-Dispersive X-ray Analysis. SRM J Res Dent Sci 2022;13:41-8

How to cite this URL:
Purakkal AT, Peedikayil FC, Vardhanan Y S, Chandru T P, Kottayi S, Melethil BY. Chemical changes in root canal dentin of primary teeth after endodontic irrigation: A Scanning Electron Microscopic and Energy-Dispersive X-ray Analysis. SRM J Res Dent Sci [serial online] 2022 [cited 2022 Jun 30];13:41-8. Available from: https://www.srmjrds.in/text.asp?2022/13/2/41/347811


  Introduction Top


In endodontics, irrigation with a suitable irrigant is essential throughout the instrumentation. It flushes away the loose, necrotic pulpal remnants and contaminated contents of the root canal system.[1] The irrigants that are presently used in dentistry are either antibacterial or decalcifying agents or their combinations. They include sodium hypochlorite, chlorhexidine, EDTA , citric acid, BioPure MTAD, ozonated water, QMix™ 2 in 1, and various herbal irrigants.[2]

Calcium and phosphorus present in hydroxyapatite crystals are the major inorganic components of dental hard tissue.[3] Mechanical instrumentation of the root canal walls results in smear layer formation, which can retain the bacteria and interfere with the sealing ability of root canal sealants.[4] Even though they have considerably increased the success rate of endodontic therapy in primary teeth, they have certain disadvantages.[5]

It has been reported that chemical agents can alter the Ca/P ratio of the dentin surface which, in turn, change the permeability and solubility of dentin. This interferes with the adhesion of dental materials to the hard tissues and makes them vulnerable to fracture.[6] The aim of the present study was to evaluate and compare the mineral content of root canal dentin after treatment with different endodontic irrigation solutions such as BioPure™ MTAD, QMix™ 2-in-1 solution, 0.9% normal saline, coconut water, and 5.25% NaOCl and uninstrumented normal teeth. The mineral content was measured using scanning electron microscopy and energy-dispersive X-ray analysis (SEM-EDXA) technique.


  Materials and Methods Top


Study design

This in vitro study was conducted for a duration of 1 year from June 2017 to July 2018.

Study setting

This study was carried out by the Department of Pedodontics and Preventive Dentistry, in association with the Department of Zoology, Calicut University, and was reviewed and approved by the Review Board and Institutional Ethical Committee of the college, KDC/19/232 P. All procedures performed in the study were conducted in accordance with the 1964 Declaration of Helsinki, as revised in 2013.

Sample size

Sixty single-rooted primary anterior teeth extracted for therapeutic reasons such as retained deciduous teeth and management of crowding were taken for this study. The tooth with at least two-thirds of root intact and tooth with patent canals were selected for the study. Tooth with gross deviation in their normal anatomy, fractured roots, and obstruction or calcification within the canal were excluded from the study. The sampling was done by a simple random method with ten teeth in each group. This was derived using the formula n = 2 ([Zα/2 + Zβ]σ/d) 2, where n = sample size per group, Zα/2 = 1.96 because α is set at 0.05, Zβ =1.28 and β is set at 0.10 (power 90%), σ =0.05, standard deviation d = 0.072, and difference in mean change between the two groups n = 2 (3.24 × 0.05/0.072) 2 = 2 × 5.06 = 10.125.

The extracted teeth were disinfected with sodium hypochlorite diluted with tap water (1:10) and stored in normal saline. Protocols for infection control as per the Occupational Safety and Health Administration and Centers for Disease Control and Prevention guideline regulations in collection, storing, sterilization, and handling were followed.

The selected samples were standardized by de-coronating them at the level of CEJ by sectioning with a water-cooled diamond disc mounted on a low-speed hand piece and superficial grooves were placed mesiodistally along the longitudinal axis in the cementum not extending to the root canal. The working length was determined by passively placing a size 10 K-file until it was just visible at the apical foramen and was adjusted to the apical foramen.

Biomechanical preparation was performed by watch-winding method using step-back technique with 21-mm-K-files size 15–40(Mani, Prime Dental Products Pvt. Ltd., India), in the entire working length of the canal by a single operator to control bias. Between every instrument, irrigation was performed with 3 ml of 0.9% normal saline for 10 s using 26-gauge needles. The depth of the irrigation needle was calculated by reducing 2 mm from the working length. All the procedures were performed in constant atmospheric temperature and in sterile condition.

Following this, the samples were divided into five groups, based on their final irrigating solution used, respectively, Group 1 – BioPure MTAD (Dentsply, Tulsa, OK), Group 2 – QMix 2 in 1 (Dentsply, Tulsa, OK), Group 3 – normal saline, Group 4 – coconut water, and Group 5 – 5.25% NaOCl (Cerkamed Chloraxid 5.25%), and Group 6 - uninstrumented teeth.

All the irrigating solutions were prepared as per the manufacturer's instructions. Coconut water was collected in its natural form in a sterile test tube by directly inserting a 26-gauge needle into one of the eyes of coconut and sterilized by pasteurizing at 63°C for 30 min in a sterile test tube using holding technique.[7]

Subsequent to the canal preparation, the samples were irrigated with a final rinse of 20 ml of the irrigant solution for about 30 s. The teeth were then carefully split longitudinally through the previously placed grooves dividing them into two halves using a mallet and a chisel. The one half of each tooth was used for the study and the remaining half was discarded. Then, the samples were transferred to the testing laboratory in a sterilized plastic container. Following fixation, the teeth were dehydrated with ascending concentrations of ethyl alcohol (70%, 90%, 95%, and twice at 100%) and were placed in desiccators for at least 24 h and gold coated and subjected for the SEM-EDXA.

The levels of six elements, namely calcium, phosphorus, oxygen, carbon, arsenic, and fluoride, on the root dentin surface were measured in the coronal and middle third using SEM-EDXA technique. The average atomic percentage of each element was calculated. Changes in the levels of the elements after the irrigation with respective final irrigants were recorded and compared with element level in the uninstrumented normal teeth. EDXA and spectrum levels in the coronal and middle third of uninstrumented teeth, saline, sodium hypochlorite [Figure 1], QMix [Figure 2], MTAD, and coconut oil are obtained.
Figure 1: EDAX photomicrographs and spectrum at (a) coronal third and (b) middle third after hypochlorite irrigation. EDAX: Energy-dispersive X-ray

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Figure 2: EDAX photomicrographs and spectrum at (a) coronal third and (b) middle third after QMix irrigation. EDAX: Energy-dispersive X-ray

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Statistical methods

Statistical analysis was done by SPSS version 20 (IBM Corporation, Chicago, Illinois, USA) using one-way analysis of variance (P < 0.001), and the comparison of means was conducted using post hoc Tukey test (P < 0.05).


  Results Top


The mean levels of elements at the coronal third and middle third of root canal dentin are shown in [Table 1]. In all the groups, except for carbon, there was a substantial drop in mean weight percentage of all mineral levels in the coronal third. The mean weight percentage of all minerals examined in the middle third of the tooth indicated a statistically significant difference in all the groups when compared to the uninstrumented teeth group.
Table 1: The mean levels of six elements of root canal dentin after treatment with endodontic irrigation solutions at the coronal and middle third

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[Table 2] shows the comparison of mean difference in mineral levels in the coronal and middle aspect between each group using the post hoc Tukey test. A statistically significant reduction in the calcium level was noted in all the groups at the coronal third than in the uninstrumented teeth group. The phosphate level at the coronal third of the radicular dentin significantly increased in all the groups except for the saline group. When the effects of MTAD on the fluoride content in the root canal dentin were compared to the other groups, it was found that the saline and uninstrumented teeth groups had significantly lower fluoride levels. When the effects of QMix™ 2 in 1 on fluoride levels of root canal dentin were compared with all the other groups, a statistically significant reduction in the coconut water, uninstrumented teeth, and saline groups was noted in the coronal aspect.
Table 2: Comparison of mean difference in mineral levels in the coronal and middle third between each groups using the post hoc Tukey test

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When the MTAD group was compared with all the other groups, a significant increase in the weight percentage of oxygen was noted for all the groups except for the uninstrumented teeth and saline groups in the coronal area. When the effects of QMix™ 2 in 1 on the oxygen content of root canal dentin were compared with the other groups, there was a significant reduction in the saline and uninstrumented teeth groups. When the effects of saline irrigation on root canal dentin were compared with all the other groups, there was a significant increase in oxygen content in all the other groups. When the effects of coconut water on root canal dentin were compared with all the other groups, there was a significant decrease in oxygen weight percentage than in uninstrumented teeth. There was also a significant reduction in oxygen content in the uninstrumented teeth group when compared to the 5.25% NaOCl group. The comparison of arsenic content of the root canal dentin after irrigation with MTAD, QMix™ 2 in 1, coconut water, and 5.25% NaOCl showed a significant increase than the saline group at the coronal third.

When comparing with uninstrumented tooth , the element levels in the middle third of the root canal dentin after irrigation with final irrigants showed a statistically significant increase in the carbon, oxygen, arsenic, and fluoride levels. The calcium and phosphate levels in all the instrumented teeth groups were significantly reduced when comparing with the uninstrumented teeth group.


  Discussion Top


Dentin is composed of inorganic components of hard dental tissues, in which calcium and phosphorus are distributed in the form of hydroxyapatite crystals.[6] By removing inorganic and organic matter from the surface of dentine, root canal irrigants can simultaneously induce changes in the mineral composition of dentine and Ca/P ratio of hydroxyapatite. These changes may affect the microhardness, permeability, and solubility of dentine, as well as the sealing of the resin-based material to the root dentin surface.

In the present study, single-rooted primary teeth were utilized considering the fact of their easy availability and to avoid strenuous cleaning and shaping in the tortuous roots of the primary molars. It is also easy to perform accurate root irrigation in these teeth.

The amount of organic substances and water in primary teeth is more compared to that of permanent teeth, resulting in a low degree of hardness and density. These structural differences make the primary teeth dentin more reactive to chemical substances.

When the calcium contents of QMix- and MTAD-treated root dentin were compared, no statistically significant difference was found. The MTAD is a mixture of tetracycline, citric acid, and Tween 80. The calcium-dissolving abilities of MTAD might be because of citric acid. The QMix™ 2 in 1 contains EDTA, chlorhexidine, and detergent. The EDTA in the QMix™ 2 in 1 can chelate with calcium ions in the hydroxylapatite crystals of radicular dentin.[5],[8] This explains the significantly reduced calcium level in QMix-treated teeth than the uninstrumented teeth.

When the calcium level of the coconut water group and the uninstrumented teeth group was compared, a significant reduction was noted in the coconut water group. There are no studies in the literature to support this finding. Coconut water is a complex blend of vitamins, minerals, carbohydrates, antioxidants, enzymes, various hormones, and other phytonutrients. It is biocompatible since its electrolyte content is similar to human plasma. The antifungal property of coconut has been proved by various studies.[5] Studies have used coconut oil as a root canal irrigant and found satisfactory results.

The calcium level of radicular dentin after treatment with 5.25% NaOCl solution showed a significant reduction than the uninstrumented teeth group in the coronal and middle aspect. This finding is supported by the studies of Nogueira et al.[9] and Zhang et al.[10] When irrigated by the NaOCl, an acidification process promoted by the OCl − ion which can contribute to the loss of mineral structure of the dentin.

The phosphorus level in the coronal third of the radicular dentin decreased after irrigation with various irrigants, but this difference was not statistically significant except for the saline group. In the middle third of the radicular dentin, the phosphorus level significantly reduced in all the irrigant groups than the uninstrumented normal teeth and 5.25% NaOCl groups. The decrease in the NaOCl group has been supported by a study by Tsuda et al.[11] The reduction in phosphorus level in radicular dentin by MTAD and QMix™ 2 in 1 is supported by the study of NogoZivanovic et al.[7] These changes in the phosphorus level by MTAD can be attributed to the low pH of doxycycline and citric acid which is a calcium chelator. The QMix 2 in 1 reduced the phosphorus level by the known effects of detergent and CHX on root dentin microhardness.[7]

The carbon content of the radicular dentin did not show any statistically significant difference by any of the irrigants in the coronal aspect, but showed a significant increase in the middle third of the NaOCl and uninstrumented teeth groups. The increase in carbon content by the NaOCl group is supported by a study by Doğan and Qalt.[12] This might be because NaOCl has ability of removing carbonate from dentin and can cause mineral accumulation on the root dentin surface.[13] When comparing the oxygen concentration of the radicular dentin in the coronal third, there was a statistically significant increase in samples treated by the irrigants except saline. In the middle third, a significant increase in oxygen concentration by all the irrigant groups than the uninstrumented teeth group was noted. The increase in oxygen concentration after irrigation with NaOCl and EDTA which is a component of QMix is undesirable because this oxygen-rich layer can significantly reduce bond strength and reduce microleakage.[14]

The primary tooth dentin appears to have potential as a biomarker for chronic fluoride intake. In the middle third of the root canal dentin, a statistically significant increase in fluoride content was noted between the QMix™ 2-in-1, uninstrumented teeth, and coconut water groups. Coconut water contains high concentration of fluoride; this might be the reason behind the increased fluoride level in that group.[15]

Arsenic was once used for the devitalization of the inflamed pulp tissue in root canal treatment. It was discarded due to its clinical complications due to prolonged use.[16] The arsenic content in radicular dentin can be a potential biomarker of ground water arsenic contamination.[17] Comparing MTAD with the other groups in the coronal third, there was a significant increase in arsenic in the saline group. There are no sudies on the changes in arsenic level after irrigation with root canal irrigants to support or contradict our study.

As this study was conducted in in vitro conditions, it may not be able to simulate the clinical situation completely; therefore, the quantitative assessment of mineral levels may vary. Other limitation of the study is that mineral levels only in a specific area can be determined by EDXA.


  Conclusion Top


The endodontic irrigating materials used in this study changed the mineral contents of root dentin. Further studies should be carried out in clinical conditions to obtain an appropriate assessment of the changes in the mineral content of the radicular dentin by irrigation with various irrigants and the effect on their clinical outcome.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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Jaju S, Jaju PP. Newer root canal irrigants in horizon: A review. Int J Dent 2011;2011:851359.  Back to cited text no. 1
    
2.
Pascon FM, Kantovitz KR, Puppin-Rontani RM. Influence of cleansers and irrigation methods on primary and permanent root dentin permeability: A literature review. Braz J Oral Sci 2006;5:1063-9.  Back to cited text no. 2
    
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Doğan MS. Relation of Trace Elements on Dental Health. Trace Elements: Human Health and Environment. 1st ed., Vol. 75899. London, United Kingdom: Intech Open; 2018. p. 71-83.  Back to cited text no. 3
    
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Hariharan VS, Nandlal B, Srilatha KT. Efficacy of various root canal irrigants on removal of smear layer in the primary root canals after hand instrumentation: A scanning electron microscopy study. J Indian Soc Pedod Prev Dent 2010;28:271-7.  Back to cited text no. 4
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5.
Purakkal AT, Peedikayil FC, Shibuvardhanan Y, Chandru TP, Kottayi S, Srikant N. Comparison of smear layer removal by MTAD, TetraClean, QMix, NaOCL, coconut water, and saline as irrigating solutions in primary teeth: An in vitro study. J Dent Res Rev 2020;7:97-104.  Back to cited text no. 5
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Zahran NF, Helal AI, Amr MA, Al-Saad KA. Trace Elements in Teeth by ICPMS. Proceedings of the 9th International Conference for Nuclear Sciences and Applications Egypt; 2008. p. 1239-46.  Back to cited text no. 6
    
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NogoZivanovic D, Kanjevac T, Bjelovic L, Ristic V, Tanaskovic I. The effect of final irrigation with MTAD, QMix, and EDTA on smear layer removal and mineral content of root canal dentin. Microsc Res Techniq 2019;82:923-30.  Back to cited text no. 7
    
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Perdigão J, Eiriksson S, Rosa BT, Lopes M, Gomes G. Effect of calcium removal on dentin bond strengths. Quintessence Int 2001;32:142-6.  Back to cited text no. 8
    
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Nogueira BM, da Costa Pereira TI, Pedrinha VF, de Almeida Rodrigues P. Effects of different irrigation solutions and protocol on mineral content and ultrastructure of root canal dentine. Iran Endod J 2018;13:209-15.  Back to cited text no. 9
    
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Zhang K, Tay FR, Kim YK, Mitchell JK, Kim JR, Carrilho M, et al. The effect of initial irrigation with two different sodium hypochlorite concentrations on the erosion of instrumented radicular dentin. Dent Mater J 2010;26:514-23.  Back to cited text no. 10
    
11.
Tsuda H, Ruben J, Arends J. Raman spectra of human dentin mineral. Eur J Oral Sci 1996;104:123-31.  Back to cited text no. 11
    
12.
Doğan H, Qalt S. Effects of chelating agents and sodium hypochlorite on mineral content of root dentin. J Endod 2001;27:578-80.  Back to cited text no. 12
    
13.
Gu LS, Huang XQ, Griffin B, Bergeron BR, Pashley DH, Niu LN, et al. Primum non nocere – The effects of sodium hypochlorite on dentin as used in endodontics. Acta Biomater 2017;61:144-56.  Back to cited text no. 13
    
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Gupta C, Singh G, Singh MP, Agarwal M, Singh KS, Mishra A. Effect of Q Mix 2 in 1, Biopure MTAD and 17% ethylene diaminetetraacetic acid on microhardness of root canal dentin: An in vitro study. Int J Prosthodont Restor Dent 2017;7:17-20.  Back to cited text no. 14
    
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Hosseini SS, Mahvi AH, Tsunodac M. Fluoride content of coconut water and its risk assessment. Fluoride 2019;52:553-61.  Back to cited text no. 15
    
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Dumlu A, Yalcinkaya S, Olgac V, Güvercin M. Osteomyelitis due to arsenic trioxide use for tooth devitalization. Int Endod J 2007;40:317-22.  Back to cited text no. 16
    
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Syed EH, Melkonian S, Poudel KC, Yasuoka J, Otsuka K, Ahmed A, et al. Arsenic exposure and oral cavity lesions in Bangladesh. J Occup Environ Med 2013;55:59-66.  Back to cited text no. 17
    


    Figures

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    Tables

  [Table 1], [Table 2]



 

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