|Year : 2015 | Volume
| Issue : 4 | Page : 279-284
Comparative evaluation of microleakage of conventional and modifications of glass ionomer cement in primary teeth: An in vitro study
AS Shruthi1, NB Nagaveni1, P Poornima1, M Selvamani2, GS Madhushankari2, VV Subba Reddy1
1 Department of Pedodontics and Preventive Dentistry, College of Dental Sciences, Davangere, Karnataka, India
2 Department of Oral and Maxillofacial Pathology and Microbiology, College of Dental Sciences, Davangere, Karnataka, India
|Date of Web Publication||18-Sep-2015|
Dr. N B Nagaveni
Department of Pedodontics and Preventive Dentistry, College of Dental Sciences, Davangere - 577 004, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aims: The aim of the present study was to evaluate the microleakage among conventional, resin modified glass ionomer cements (GIC), and compomer cements in primary teeth. Materials and Methods: Forty-five over retained non carious primary molars beyond exfoliation time were collected and randomly divided into three groups (n = 15). Group A: GC Fuji II; Group B: Vitremer; Group C: Compoglass F. A standard Class V cavity was prepared on the buccal surface of each tooth with no mechanical retention and restored accordingly. Then all the samples were subjected to thermocycling for 250 cycles at different temperatures and covered with nail varnish. Later, samples were immersed in 0.5% methylene blue dye for 24 h. Teeth were sectioned buccolingually through the center of the restoration and studied under a stereomicroscope for dye penetration. Data obtained were analyzed using Kruskal-Wallis ANOVA and Mann-Whitney U-test. Results: Samples restored with vitremer showed comparatively higher microleakage than the samples in other groups. However, overall there were no significant difference between the microleakage scores of the samples in all three groups (P > 0.05). Conclusion: It can be concluded that none of the three GICs was free from microleakage. Hence, further research is required to compare microleakage of the newer material.
Keywords: Glass ionomer, microleakage, modified glass ionomer, primary teeth
|How to cite this article:|
Shruthi A S, Nagaveni N B, Poornima P, Selvamani M, Madhushankari G S, Subba Reddy V V. Comparative evaluation of microleakage of conventional and modifications of glass ionomer cement in primary teeth: An in vitro study. J Indian Soc Pedod Prev Dent 2015;33:279-84
|How to cite this URL:|
Shruthi A S, Nagaveni N B, Poornima P, Selvamani M, Madhushankari G S, Subba Reddy V V. Comparative evaluation of microleakage of conventional and modifications of glass ionomer cement in primary teeth: An in vitro study. J Indian Soc Pedod Prev Dent [serial online] 2015 [cited 2019 Dec 15];33:279-84. Available from: http://www.jisppd.com/text.asp?2015/33/4/279/165662
| Introduction|| |
Carious teeth are the most common complaint in children. In pediatric dentistry restoring these teeth is one of the major treatments. The ideal requisites for a restorative material are that it should have a good color stability, biocompatibility, and have a coefficient of thermal expansion are similar to that of natural tooth structure, excellent marginal seal, and should have the ability to adhere chemically to both enamel and dentine.  Microleakage is the most common causes of failure of almost all restorative materials since it is a major contributing factor to secondary caries and pulpal irritation  and this type of leakage around dental restorative materials is a major problem in clinical dentistry.  It may be defined as the clinically undetectable passage of bacteria, fluids, molecules, or ions between a cavity wall and the restorative material applied to it. This may occur because of dimensional changes, changes in temperature, and mechanical stress, or lack of adaptation of the restorative material resulting in a gap at the tooth-material junction. 
There has always been a keen interest in the adaptation of dental restorative materials to the walls of cavities and the retentive ability of a material to seal the cavity against the ingress of oral fluids and microorganisms.  This seepage can cause hypersensitivity of restored tooth, tooth discoloration, recurrent caries, and accelerated deterioration of the restorative material.  Over 50 years, many changes have been occurred in the development of restorative materials.  After introducing glass ionomer cements (GIC), they became popular because of their chemical adhesion and fluoride release property.  These physical and chemical properties make GIC excellent restorative material for the management of carious teeth in pediatric dentistry. However, these traditional GICs are associated with some disadvantages such as delayed setting reaction, low early strength, and other poor esthetics.  As a result, the conventional GIC has undergone many modifications to overcome these limitations. The introduction of newer GICs such as light cured GIC, resin modified GIC (RMGIC), compomer, and nanofilled GIC has touched the current restorative field with maximum benefits. Therefore, the present in vitro study is undertaken to evaluate the microleakage among conventional, RMGIC, and compomer cements in primary teeth.
| Materials and Methods|| |
Forty-five noncarious primary molars extracted for orthodontic purpose or because of over retention were selected for the study. Surface debridement of all the teeth was performed with a hand-scaling instrument and the teeth were stored in normal saline. The teeth were randomly divided into three groups consisting of 15 teeth each according to the glass ionomer materials used as follows, Group A (GC Fuji II), Group B (Vitremer), and Group C (Compoglass F). A standard Class V cavity was prepared on the buccal surface of each tooth with no mechanical retention using diamond straight bur under air - Water cooling. The preparations measured 4 mm long, 2 mm width, and 2 mm deep. The depth of the cavity was measured with a periodontal probe.
For Group A, dentin conditioner was applied to the walls of the cavity for 15 s with a cotton pellet, rinsed with water for 30 s and blotted dry with tissue paper. The standard powder to liquid ratio was achieved with 1 level scoop of powder to 1 drop of liquid. Using the plastic spatula, the powder and liquid were mixed according to the manufacturer's instructions, and finally, the cavity was restored. Excess material was removed and a coat of petroleum jelly was applied over the restoration.
For Group B, the primer was applied to the cavity and was dried using an air syringe for about 15 s. Then the dried primed surfaces were light cured for 20 s. The light cured surfaces appeared glossy. The powder and liquid were mixed according to the manufacturer's instructions. Mixed GIC was then loaded into a delivery tip followed by the insertion of a piston, which flushes the excess cement from the back of the delivery tip. Then the loaded cement was syringed into the prepared cavity by keeping the syringe tip immersed in the material to minimize air entrapment. The restoration was then condensed and contoured with a plastic filling instrument and cured for 40 s.
For Group C, the cavity was dried and etched for 30 s. After 30 s the etchant was washed and the cavity was dried again, but not desiccated. Then dentin bonding agent was applied to the enamel and dentin and cured for 20 s. Cavifils of the compoglass F was again fitted to the dispenser and was applied in layers of 2 mm thickness and excess material was removed and light cured for 40 s.
All the teeth (45) from the three groups were then subjected to thermocycling for 250 cycles at temperatures of 5°C ± 2°C, 37°C ± 2°C, and 60°C ± 2°C in a controlled water bath using a thermostat.
The apices of all the teeth were sealed with acrylic resin. Each tooth was covered with two coats of nail varnish except for an area approximately 2 mm from the periphery of the restoration. All the teeth were immersed in 0.5% methylene blue dye for 24 h. After removal from the dye solution, the teeth were allowed to dry. Then teeth were sectioned buccolingually through the center of the restoration using a diamond disk.
The specimens were then studied under a stereomicroscope with a magnification of ×20 to measure the depth of the dye penetration on the occlusal and gingival walls of both halves of the teeth.
The scoring was done as described by Khera and Chan. 
0 = No leakage.
1 = Dye penetrating is to the lesser than and up to one-half of the depth of the prepared cavity.
2 = Dye penetrating is to more than one-half of the depth of the prepared cavity but not up to the junction of the axial and occlusal or gingival wall.
3 = Dye penetrating up to the junction of the axial and occlusal or gingival wall but not including the axial wall.
4 = Dye penetration including the axial wall.
The results were tabulated and statistically analyzed by using Kruskal-Wallis ANOVA for multiple group comparison followed by Mann-Whitney U-test for pairwise comparison.
| Results|| |
In Group A, 46.7% of samples showed score 0 and 53.3% of samples showed score 1, whereas in Group B, 33.3% of samples showed score 0, 53.4% of samples showed dye score 1, and 13.3% of samples showed score 2, and in Group C, 46.7% of samples showed score 0, 33.3% of samples showed score 1, and 20.0% of samples showed score 2 [[Table 1] and Graph 1].
Kruskal-Wallis ANOVA test for different groups showed the mean score ± standard deviation (SD) of 0.5 ± 0.5 for Group A (GC Fuji II), mean score ± SD of 0.8 ± 0.7 for Group B (Vitremer), and mean score ± SD of 0.7 ± 0.8 for Group C (Compoglass F) showing H value of 3.15 and P = 0.2 [Table 2].
Mann-Whitney's U-test was applied to compare the significance in microleakage scores between any of the two groups studied. When Group A was compared with Group B, the P value obtained was 0.35, which was not significant. When Group A was compared with Group C, the P value was 0.62, which was found not significant and when Group B was compared with Group C, the P value was 0.74, which was again not statistically significant [Figure 1], [Figure 2], [Figure 3] and [Table 3].
|Figure 2: Score 1 (dye penetrating is to the lesser than and up to one-half of the depth of the prepared cavity)|
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|Figure 3: Score 2 (dye penetrating is to more than one-half of the depth of the prepared cavity but not up to the junction of the axial and occlusal or gingival wall)|
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| Discussion|| |
Microleakage is the most common causes of failure of almost all restorative materials and there has always been a keen interest in the adaptation of dental restorative materials to the walls of cavities and the retentive ability of a material to seal the cavity against the ingress of oral fluids and microorganisms. , This seepage can cause hypersensitivity of restored tooth, tooth discoloration, recurrent caries, pulpal injury, and accelerated deterioration of the restorative material.  Accordingly, there is an interest in finding an ideal restorative material which has better bond characteristics, thus, minimizing microleakage and reducing the potential for caries development. 
An important advancement in glass ionomer technology that has influenced dentistry for children is the development of the RMGIC, which was introduced in the early 1990s.  The RMGIC harden initially by free-radical photopolymerization of the resin component in the formulation. A chemical resin polymerization reaction and the glass ionomer setting reaction subsequently progress. The addition of the resin component not only decreases initial hardening time and handling difficulties, but also substantially increases wear resistance and physical strengths of the cement. This restorative material has been established in pediatric practice and their favorable longevity as a permanent restoration in primary teeth have been demonstrated in several clinical studies. ,
Compomers have become available more recently, which is in 1992 and are recommended for use as a pediatric restorative material. They are the single component materials that combine the advantage of both composite resin and GIC  and are officially termed polyacid-modified, resin-based composites. The mechanical properties of tensile and flexural strength, as well as wear resistance of compomers, are superior to that of glass ionomers. 
The current study examined the microleakage of different types of glass ionomer restorations placed in Class V cavities in primary teeth and subjected to thermocycling. This thermocycling is a standard protocol in the restorative literature when bonded materials are evaluated, simulating in vivo aging by subjecting bonded materials to cyclic exposures of hot and cold temperatures and shows the relationship coefficient of thermal expansion between the tooth and the restorative material. ,
The relationship between marginal leakage in restorations and the type of restorative materials has been extensively studied in both laboratory and clinical studies. In the absence of definitive clinical data, laboratory microleakage studies  are a well-accepted method of screening the marginal sealing efficiency.  There are several methods to detect microleakage. These include the use of dyes, chemical tracers and radioactive tracers, scanning electron microscopy, neutron activation analysis, and fluid filtration. Among these methods, measurement of dye penetration on sections of restored teeth is the most commonly used technique  because it is simple, inexpensive, fast technique, and does not require the use of complex laboratory equipments. Several dye penetration studies have been performed using methylene blue, India ink, basic fuschin, crystal violet, as well as fluorescin.  Hence, the same method of dye penetration was employed in the present study and the dye used was methylene blue.
The results obtained in this study showed that all the three restorative materials that were investigated exhibited no difference in microleakage. However, in contrary the results obtained in other study  showed that all the three restorative materials that they investigated exhibited more microleakage on the gingival margins than on the occlusal margins. However, no material was able to completely eliminate microleakage and also this study was conducted on permanent teeth not on primary teeth. This finding is in agreement with other studies which concluded that cavity preparations with enamel margin result in consistently stronger bonds. Unique challenges are encountered with dentin surface bonding due to enamel that is 92% inorganic hydroxyapatite and dentin that is 45% inorganic by volume. ,
A study which also showed that there was no statistically significant difference in the microleakage of between GC Fuji II and GC Fuji II LC (RMGIC) both occlusal and gingival margins. ,, However, few studies have shown that there is statistically significant difference in microleakage of these materials. , This could be due to the difference in experimental designs and testing methods used in these studies.
In accordance to the present study, the results in another study demonstrated that none of the three GICs was free from microleakage. However, the nanofilled RMGIC showed the least microleakage. Gorseta et al. observed that nanoionomer showed lower microleakage values when compared with the conventional GIC, and emphasized the efficacy of nanoionomer cements to be used in routine dental practice. 
A study which was carried on both primary and permanent teeth showed that the conventional GIC (Fuji II) showed more leakage than all other groups. However, Fuji IX, the improved conventional GIC behaved similar to the composite resin and to the RMGIC (Vitremer). Results suggested that the leakage in primary and permanent teeth may vary individually with each type of material, one showing greater primary tooth leakage, while another showing more permanent teeth leakage.  According to Singla et al.  the mean microleakage of compomer was 2.47 after 24 h dye immersion. He said this microleakage pattern would have been attributed to higher resin content as compared to Fuji II LC, which causes more polymerization shrinkage leading to increased microleakage. He also said that there was more microleakage in deciduous molars when compared with permanent molars, but it was not statistically significant.
A study similar to the present one, where they included Fuji IX GP, Fuji II LC, and compoglass to evaluate tensile bond strength and microleakage on primary teeth.  Here, a total of 82.8% of Fuji II LC samples did not exhibit any microleakage. The microleakage of RMGIC was lesser than compomers, this was also supported by Toledano et al.,  Castro and Feigal,  Zyskind et al.,  Gladys et al.,  Rodrigues et al.  However, in the current study, RMGIC showed more microleakage than compomer. In the above-mentioned study, they said only 46.9% of the compomer samples showed no microleakage. This is comparable to the present study that 46.70% of compoglass samples did not show microleakage and also only 33.3 % of vitremer samples did not show microleakage. Cehreli et al.  in their study said that the absence of surface protection resulted in significant reduction in the marginal sealing efficiency of both conventional GIC and glass carbomer cement with the later yielding the greatest amount of microleakage among the test groups. As with other resin-based filling materials, it can be assumed that surface protection would significantly increase the marginal sealing of the compomer.  In an in vivo study  authors have discussed the amount of microleakage on the buccal surface of deciduous molars after restoring the cavity with GC Fuji II LC and GC Fuji IX GP. Where there was more microleakage in RMGIC samples than conventional GIC samples. This is similar to the results what we have obtained in the present study.
The present study indicated that there was no significant difference in the microleakage between all three groups. However, after comparing the individual scores of microleakage in each samples, it showed that the RMGIC (vitremer) showed more microleakage when compared with GC Fuji II and compoglass F.
There are certain limitations noticed in this study:
- This was an in vitro study, where the exact oral environment could not be simulated.
- Marginal integrity was evaluated using a single parameter, that is, estimation of microleakage by dye penetration method only.
| Conclusion|| |
In spite of these limitations, this study has hinted on the amount of microleakage of conventional and different modification of GIC in primary teeth and also showed that there was no complete elimination of microleakage in any of the groups. Hence, further research is required to compare microleakage of the newer cements such as RMGIC and compomers.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]