Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 14  |  Issue : 1  |  Page : 47-51

The Electrical Conductivity and Dielectric Properties of Dental Glass Ionomer Cements: In Vitro Study


1 Associated Professor, Department of pedodontics and preventive dentistry, Mallareddy Dental College for Womens, Hyderabad, Telangana, India
2 Associated Professor, Department of oral medicine, Mallareddy Dental College for Womens, Hyderabad, Telangana, India
3 Department of Oralpathology & Microbiology, Army college of Dental Science, Secunderabadh, Telangana, India
4 Associated Professor, Department of Oralpathology & Microbiology. Mallareddy Dental College for Womens, Hyderabad, India
5 Associated Professor, Department of Pedodontics and Preventive Dentistry, Mallareddy Dental College for Womens, Hyderabad, India
6 DDS, USA

Date of Submission16-Nov-2021
Date of Decision08-May-2022
Date of Acceptance11-May-2022
Date of Web Publication05-Aug-2022

Correspondence Address:
Dr. Kola Srikanth Reddy
Department of Pedodontics & Preventive Dentistry, Mallareddy Dental College for Womens & Hospital, Hyderabad, Telangana
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jofs.jofs_260_21

Rights and Permissions
  Abstract 


Introduction: Glass ionomer cements find extensive use as dental restoratives for their biocompatibility, favorable mechanical properties, and sustained fluoride ion release. The measurement of the dielectric constant and resistivity of these materials has been used to monitor their setting characteristics. The aims was to study the conductivity and dielectric constant of the dental glass ionomer cement. Materials and Methods: Commercially available GIC cement was mixed according to the manufacturer’s instructions. The resistivity of the samples was measured using an Inductance(L), Capacitance(C), Resistance(R) meter. The measurements were made both in the initially set samples and after the samples were set for 24 hours. The conductivity and dielectric constant of the samples were calculated. Results: There was an increase in the resistivity of the samples and hence a decrease in the conductivity and decrease in the dielectric constant of the samples with an increase in setting time. Conclusion: With the progression of the setting reaction, the Glass ionomer cement changes from ionic to nonionic state, hence causing an increase in the resistivity and decrease in the conductivity and dielectric constant, which suggests that GIC acts as an insulator to thermal and galvanic currents.

Keywords: Conductivity, dielectric constant, glass ionomer cement, resistivity


How to cite this article:
Reddy KS, Nareshnaik D, Sunil VV, Ali M, Kumari GA, Chatta JS. The Electrical Conductivity and Dielectric Properties of Dental Glass Ionomer Cements: In Vitro Study. J Orofac Sci 2022;14:47-51

How to cite this URL:
Reddy KS, Nareshnaik D, Sunil VV, Ali M, Kumari GA, Chatta JS. The Electrical Conductivity and Dielectric Properties of Dental Glass Ionomer Cements: In Vitro Study. J Orofac Sci [serial online] 2022 [cited 2022 Dec 3];14:47-51. Available from: https://www.jofs.in/text.asp?2022/14/1/47/353471




  Introduction Top


Glass ionomer cements have been used for over 40 years since they were developed in 1969 by Wilson et al.,[1] who were trying to develop the ideal artificial material for the replacement of tooth tissue. Glass ionomer cement has been usually preferred as a restorative material in pediatric dentistry due to their low sensitivity to moisture, good adhesion ability,[2] and high fluoride content[3] and are used as a lining, fissure sealant and as a filling material.

They are extensively used in dentistry for a number of different reasons. However, insufficient mechanical properties limit the use of the material and numerous researches have been carried out in attempts to improve the longevity and the success of the restorations.[4],[5] Chiefly, they adhere to both untreated tooth enamel and dentine, through the ionic bonding of the Ca2+ ions within the dental tissue to the polymer chains within the cured cement, which means they require little mechanical fixation.[1],[6]

In addition, the coefficient of thermal expansion for GIC is low and close to the values of tooth structure.[7] The material was based on the hardening reaction among aluminosilicate glass powders and aqueous solutions of polymers and copolymers of acrylic acid.[8]. Although a considerable number of papers are available about the effect of GIC and its setting processes, there is little information on the electrical properties of dental cements.[9]

The study of the properties of dental cements is interesting for two reasons: It provides information about (i) the setting reaction of the cement and (ii) the likely function of an electrical insulator.[10]

Several studies using SEM,[11] IR,[12] and Raman spectroscopies[13] as well as solid-state high-resolution nuclear magnetic resonance (NMR) studies[14] are reported on these materials to study the relationship between structure, composition, setting reaction, and the release of fluorine and other ions like Al3+. But so far no report has been found for the temperature-dependent ionic conductivity of these materials in the solid state. The measurement of the dielectric constant and resistivity of these materials is used to monitor their setting characteristics.[15],[16]

The present study shows the changes in relative permittivity (Dielectric constant K) and Resistivity p during the setting of GICements.


  Materials and Methods Top


Ethical approval for this study (protocol no. IERC-MDC.7/2019) was provided by Institutional ethical committee of Mamtha Dental college and Hospital, khammam on 16 july 2019.

The study consisted of glass ionomer cement type II (GC Japan), silver electrode paste, stainless steel framework, and LCR meter (Pacific Electronics).

Commercially available glass ionomer cement was chosen for the present investigations. The glass powder and the polymeric liquid were mixed according to the manufacturer’s instructions. The thoroughly mixed paste was transferred to stainless steel die with 9 mm diameter holes and pressed into pellets of 3 mm diameter. The cement was allowed to be set for more than 24 hours at room temperature (300 K) in a dry atmosphere under mild pressure. The pellets used for the study of electrical properties were coated with a thin layer of SILVER ELECTRODING on either side.

The resistivity of the sample is measured using an impedance electrometer. The capacitance of the sample is measured using an LCR meter. These measurements are taken in both the initially set sample and after the samples are set for 24 hours. The conductivity of the sample is measured from the resistivity values of the sample. The dielectric constant or relative permittivity of the sample is measured from the capacitance values of the sample.


  Results Top


[Table 1] and Graph 1 show that there is an increase in the resistivity of the cement and hence a rapid decrease in the conductivity of the cement immediately after the setting reaction in the present study.
Table 1 Measurement of voltage and resistivity of GIC

Click here to view


There is also a decrease in the dielectric constant with the progression of the setting reaction in the present study [[Table 2], Graph 2].
Table 2 Measurement of voltage and capacitance of GIC

Click here to view



  Discussion Top


The GICs contain a hydrated polycarboxylate metal matrix within which the aluminosilicate glass particles are bound.[3]. Once the glass powder is mixed with aqueous polycarboxylic acid, a reaction between the alkaline glass powder and the unsaturated acid results in the formation of a salt gel. The acid-base reaction in the salt gel leads to the formation of a bonding matrix in which water serves as a reaction medium and also as an essential component of the salt gel containing metal carboxylate complexes formed in the reaction. This can be considered a primary reaction.[17].
Figure 1 GIC mixed according to manufactures instruction

Click here to view
Figure 2 GIC pressed into pellets of 3 mm diameter

Click here to view
Figure 3 Cement coated with silver electrode paste and placed in stainless steel framework

Click here to view
Figure 4 Impedance electrometer

Click here to view
Figure 5 LCR meter

Click here to view


One of the reaction mechanisms is fluoride release. Systematic study of fluoride release has indicated that irrespective of the make all GIC materials released the maximum fluoride ions in the first 24 hours, followed by a drop and stabilization with the gradual release.[18]. This gives rise to great ionic movement like that of the fluoride ions.[19].

In the present study, the glass ionomer cement set within 2 to 3 minutes from mixing by an acid-base reaction. The first step is a reaction with hydrated protons from the polyacid at basic sites on the surface of the glass particles. This results in the movement of ions such as Na+ and Ca2+ (or Sr2+) from the glass into the polyacid solution, followed quickly by Al3+ ions. These ions then interact with the polyacid molecules to form ionic cross-links and solubilized polysalt that forms the rigid framework for the set cement.

When this setting reaction occurs, all of the water becomes incorporated into the cement and no phase separation occurs. The setting of glass ionomer cements has been studied by various spectroscopic techniques, including Fourier transform infrared spectroscopy and 13C NMR spectroscopy.

The overall reaction appears to take place in two steps in a diffusion-controlled process.[20]. The first step is the formation of ionic cross-links, as we have seen, and this is responsible for the immediate hardening process. Subsequently, there is a cross-linking process involving Al3+ ions that takes about 10 minutes to be clearly identified spectroscopically.[21].

This second step is slow and continues for approximately a day.[22]. After this initial hardening, there are further reactions, which take place slowly and are together known as maturation. They are associated with various changes in the physical properties of the resulting glass ionomer cement.[23]. In addition, the proportion of tightly bound water within the structure increases.

Changes in the dielectric properties of dental cements could provide a method of monitoring the material. Work by Braden et al.[24]-[27] showed that during the setting reaction of glass ionomer cements, the dielectric properties change, potentially providing the ability to monitor the setting reaction of the cement within the tooth. In this theory, it would also be possible to monitor other changes such as fractures and damage to the cement, as the dielectric properties will change as a result of such distortions.[28]. Based on the observations of Braden et al.,[24]-[27] it is known that glass ionomer cements behave dielectrically in a comparable way to capacitors, which is due to the glass particulates that form part of their structure.





There was a rapid decrease in conductivity immediately after setting in the present study. The rapid decrease in specific conductivity that took place in the cement paste before and immediately after setting indicates that a precipitation reaction occurs and is accompanied by a decrease in H3O+ concentration, which conducts much of the current.[8]

In the present study, the electrical conductivity decreased rapidly with the progression of the setting reaction in 24 hours. Insoluble ionic compounds conduct electrically as well as in aqueous phases. Loss of conductivity is the result of a decrease in hydrogen ion concentration.[20]

The present study showed a decrease in relative permittivity. Relative permittivity values are consistent with a high ionic content of the cement.[26] When mixed with water, the acids are reconstituted, resulting in the release of H3O+ ions, which accounts for the steep initial fall in resistivity. However, as the acid begins to attack the glass, precipitation initial fall in resistivity. However, as the acid begins to attack the glass, precipitation of polysalts occurs with a reduction in H3O+ ions and a rise in resistivity.[25]

DC resistivity and dielectric measurements of GIC were reported earlier.[8] These studies indicate that resistivity versus temperature increases and dielectric constant versus frequency decreases gradually with an increase in setting time. The trend seems to be the same irrespective of the make and the powder to liquid ratio. These studies indicate that the cements are highly ionic and polar and more conductive than other cements.

Electrical conductivity studies indicate that resistivity and dielectric constant increase with the increase in setting time, which suggests that GIC is ionic, polar, and more conductive than other cements.[29]


  Conclusion Top


There was an increase in the resistivity and decrease in the conductivity and dielectric constant, which suggests that GIC acts as an insulator to thermal and galvanic currents. This study also indicates that these GICs are ionic, polar, and more conductive than other ones.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Wilson AD, Nicholson JW Acid-base cements .Their bio medical and industrial applications. Cambridge university press. 1993.  Back to cited text no. 1
    
2.
Kilpatrick NM. Glass ionomer cements: their application in children, Part 1. Dent Update 1996;23:236–8.  Back to cited text no. 2
    
3.
Croll TP. Glass ionomers for infants, children, and adolescents. J Am Dent Assoc 1990;120:65–8.  Back to cited text no. 3
    
4.
Skrinjaric K, Vranic DN, Glavina D, Skrinjaric I. Heat-treated glass ionomer cement fissure sealants: retention after 1 year follow-up. J Paediatr Dent 2008;18:368–73.  Back to cited text no. 4
    
5.
Yan Z, Sidhu SK, McCabe JF. The influence of microstructure on thermal response of glass ionomers. J Mater Sci Mater Med 2007;18:1163–6.  Back to cited text no. 5
    
6.
Sidhu Sharanbir K, schmaltz Goft friend. The biocompability of Glass ionomer cement materials. Am J dent 2001;14:387–96.  Back to cited text no. 6
    
7.
Moshavernia A, Anasa S, Movasaghia Z, Billington RW, Darrc JA, Rehman IU. Modification of conventional Glass ionomer cements with N-vinylpyrorolidone containing polyacids, nano-hydroxy and fluoropatite to improve mechanical properties. Dent Mater 2008;24:1381–90.  Back to cited text no. 7
    
8.
Wilson K. Dental silicate cements: electrical conductivity. J Dent Res 1968;47:1311–4.  Back to cited text no. 8
    
9.
Crowley CsM, Pembroke T, Hampshire S, Along term study of the setting reactions of Glass ionomer cements. Conference paper. 2011. university of Limerick.  Back to cited text no. 9
    
10.
Tay B. Dielectric properties of Glass ionomer cements. J Dent Res 1981;60:1311–4.  Back to cited text no. 10
    
11.
Barry TI, Clinton DJ, Wilson AD. The structure of a Glass ionomer cement and its relationship to the setting process. J Dent Res 1979;58:1072–9.  Back to cited text no. 11
    
12.
De Maeyer EAP, Verbeeck RMH, Vercruysse CWJ. Infrared spectrometric study of acid-degradable glasses. J Dent Res 2002;81:552–5.  Back to cited text no. 12
    
13.
Young AM, Sherpa A, Pearson G, Schottlander B, Waters DN. Use of Raman spectroscopy in the characterisation of the acid-base reaction in Glass ionomer cements. Biomaterials 2000;21:1971–9.  Back to cited text no. 13
    
14.
Stamboulis A, Matsuya S, Hill RG et al., MAS-NMR spectroscopy studies in the setting reaction of Glass ionomer cements. J Dent 2006;34:574–81.  Back to cited text no. 14
    
15.
Tay WM, Braden M. Materials science di-electric properties of Glass ionomer cements-further studies. J Dent Res 1981;60:1311–14.  Back to cited text no. 15
    
16.
Tay WM, Braden M. Thermal diffusivity of Glass ionomer cement. J Dent Res 1987;66:1040–3.  Back to cited text no. 16
    
17.
Eden OR, Foster GM, Hooper RM. Investigation of the mechanical performance of young Glass ionomer cement using dynamic mechanical analysis. J Mater Sc Mater Med 2003;14:373–8.  Back to cited text no. 17
    
18.
DeMaeyer EAP, Verbeeck RMH, Vercruysse CWJ. Stoichiometry of the leaching process of fluoride-containing aluminosilicate Glass ionomer glasses. J Dent Res 1999;78:1312–8.  Back to cited text no. 18
    
19.
De Maeyer EAP, Verbeeck RMH. X-ray diffraction study of acid-degradable glasses. J Dent Res 2001;80:1764–7.  Back to cited text no. 19
    
20.
Crisp S, Pringuer MA, Wardleworth D, Wilson AD. Reactions in Glass ionomer cement: II. An infrared spectroscopic study. J Dent Res 1974;53:1414–9.  Back to cited text no. 20
    
21.
Pires R, Nunes TG, Abrahams I, Hawkes GE, Morais CM, Fernandez C. Stray-field imaging and multinuclear magnetic resonance spectroscopy studies on the setting of a commercial Glass ionomer cement. J Mater Sci Mater Med 2004;15:201–8.  Back to cited text no. 21
    
22.
Zainuddin N, Karpukhina N, Hill RG, Law RV. A long-term study on the setting reaction of Glass ionomer cement by 27Al MAS-NMR spectroscopy. Dent Mater 2009;25:290–5.  Back to cited text no. 22
    
23.
Mount GJ. Color Atlas of Glass Ionomer Cement. 2nd ed. London, UK: Martin Dunitz; 2002.  Back to cited text no. 23
    
24.
Braden M, Clarke RL. Dielectric properties of zinc oxide-eugenol type cements. J Dent Res 1974;53:1263–7.  Back to cited text no. 24
    
25.
Tay WM, Braden M. Dielectric properties of Glass ionomer cements--further studies. J Dent Res 1984;63:74–5.  Back to cited text no. 25
    
26.
Braden M, Clarke RL. Dielectric properties of polycarboxylate cements. J Dent Res 1975;54:7–9.  Back to cited text no. 26
    
27.
Tay WM, Braden M. Dielectric properties of Glass ionomer cements. J Dent Res 1981;60:1311–4.  Back to cited text no. 27
    
28.
Chung DDL. Damage in cement-based materials, studied by electrical resistance measurement. Mater Sci Eng Rep 2003;42:1–40.  Back to cited text no. 28
    
29.
Babu TA, Sastry DL. Studies on electrical and thermal properties of dental Glassionomer cement. J Biomed Sci Eng 2012;5:634–8.  Back to cited text no. 29
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2]



 

Top
 
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

 
  In this article
Abstract
Introduction
Materials and Me...
Results
Discussion
Conclusion
References
Article Figures
Article Tables

 Article Access Statistics
    Viewed432    
    Printed50    
    Emailed0    
    PDF Downloaded54    
    Comments [Add]    

Recommend this journal