|Year : 2022 | Volume
| Issue : 1 | Page : 47-51
The Electrical Conductivity and Dielectric Properties of Dental Glass Ionomer Cements: In Vitro Study
Kola Srikanth Reddy1, Dungavath Nareshnaik2, Veera Venkata Naga Sunil3, Mirmujahed Ali4, Ganapathy Aruna Kumari5, Jemina Shiny Chatta6
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 Submission||16-Nov-2021|
|Date of Decision||08-May-2022|
|Date of Acceptance||11-May-2022|
|Date of Web Publication||05-Aug-2022|
Dr. Kola Srikanth Reddy
Department of Pedodontics & Preventive Dentistry, Mallareddy Dental College for Womens & Hospital, Hyderabad, Telangana
Source of Support: None, Conflict of Interest: None
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 Aug 7];14:47-51. Available from: https://www.jofs.in/text.asp?2022/14/1/47/353471
| Introduction|| |
Glass ionomer cements have been used for over 40 years since they were developed in 1969 by Wilson et al., 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, and high fluoride content 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., 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.,
In addition, the coefficient of thermal expansion for GIC is low and close to the values of tooth structure. The material was based on the hardening reaction among aluminosilicate glass powders and aqueous solutions of polymers and copolymers of acrylic acid.. 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.
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.
Several studies using SEM, IR, and Raman spectroscopies as well as solid-state high-resolution nuclear magnetic resonance (NMR) studies 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.,
The present study shows the changes in relative permittivity (Dielectric constant K) and Resistivity p during the setting of GICements.
| Materials and Methods|| |
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|| |
[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.
There is also a decrease in the dielectric constant with the progression of the setting reaction in the present study [[Table 2], Graph 2].
| Discussion|| |
The GICs contain a hydrated polycarboxylate metal matrix within which the aluminosilicate glass particles are bound.. 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..
|Figure 3 Cement coated with silver electrode paste and placed in stainless steel framework|
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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.. This gives rise to great ionic movement like that of the fluoride ions..
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.. 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..
This second step is slow and continues for approximately a day.. 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.. 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.- 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.. Based on the observations of Braden et al.,- 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.
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.
The present study showed a decrease in relative permittivity. Relative permittivity values are consistent with a high ionic content of the cement. 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.
DC resistivity and dielectric measurements of GIC were reported earlier. 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.
| Conclusion|| |
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.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2]