Indian Journal of Dental Research

ORIGINAL RESEARCH
Year
: 2020  |  Volume : 31  |  Issue : 2  |  Page : 291--296

Microleakage patterns of glass ionomer cement at cement-band and cement-enamel interfaces in primary teeth


P Shankar1, Ramesh Venkatesan2, D Senthil1, J Trophimus1, CU Arthilakshmi3, Philomine Princy2,  
1 Department of Paedodontics and Preventive Dentistry, SRM Dental College and Hospital, Ramapuram, Chennai, Tamil Nadu, India
2 Department of Restorative Dentistry, Al Farabi Dental College, Jeddah, Saudi Arabia
3 Department of Paedodontics and Preventive Dentistry, Chettinad Dental College and Research Institute, Kelambakkam, Chennai, Tamil Nadu, India

Correspondence Address:
Dr. P Shankar
Department of Paedodontics and Preventive Dentistry, SRM Dental College and Hospital, Ramapuram, Chennai - 600 089, Tamil Nadu
India

Abstract

Context: In-vitro studies of microleakage are an initial screening method to assess the maximum theoretical loss of sealing ability in-vivo. Aims: Our objective was to determine and compare microleakage patterns of conventional glass ionomer cement (GIC) and resin-modified GIC (RMGIC) for band cementation. Methods: Forty caries-free second primary molars were randomly divided into two groups of 20 teeth each. Preformed molar bands in the two groups were cemented to enamel with one of two types of cement: Conventional GIC (Fuji I, GC Corporation; Tokyo, Japan) and RMGIC (Fuji Plus, GC Corporation; Tokyo, Japan). A dye penetration method was used for microleakage evaluation. Microleakage was determined by a stereomicroscope for the cement-band and cement-enamel interfaces. Statistical Analysis Used: Statistical analysis was performed with Kruskal-Wallis and Mann-Whitney U tests. Results: The mean microleakage value for conventional GIC (Fuji I) at cement-band and cement-enamel interfaces was 2.41 mm and 2.15 mm, respectively. The mean microleakage value for RMGIC (Fuji Plus) at cement-band and cement-enamel interfaces was 0.44 mm and 0.46 mm, respectively. Compared to conventional GIC, RMGIC showed less microleakage at both cement-band and cement-enamel interfaces. P < 0.001 and it was statistically highly significant. Conclusions: Bands cemented with RMGIC had significantly less microleakage between the cement-band and cement-enamel interfaces than conventional GIC



How to cite this article:
Shankar P, Venkatesan R, Senthil D, Trophimus J, Arthilakshmi C U, Princy P. Microleakage patterns of glass ionomer cement at cement-band and cement-enamel interfaces in primary teeth.Indian J Dent Res 2020;31:291-296


How to cite this URL:
Shankar P, Venkatesan R, Senthil D, Trophimus J, Arthilakshmi C U, Princy P. Microleakage patterns of glass ionomer cement at cement-band and cement-enamel interfaces in primary teeth. Indian J Dent Res [serial online] 2020 [cited 2020 Sep 25 ];31:291-296
Available from: http://www.ijdr.in/text.asp?2020/31/2/291/284586


Full Text



 Introduction



Loss of dental arch circumference due to premature loss of primary molars is a common presentation in the primary and mixed dentitions. This reduction in arch length circumference may compromise the eruption of succedaneous teeth. One approach is to control the space created from the premature loss of primary teeth by the provision of a space maintainer appliance.[1] Space maintainers are fixed or removable appliances used to preserve arch length following the premature loss or elective extraction of tooth/teeth.[2]

Retention is provided mechanically by the band's close adaptation to the tooth surface assisted by the cement lute. For most of this century, zinc phosphate cement has been used widely for band cementation, but it has several disadvantages for this purpose, being brittle, having a relatively high solubility in the mouth, and weak adherence to tooth substance.[3]

The most commonly reported reason for the failure of band and loop space maintainer is the breaking of the cement lute or simply by loss of cement.[1] Fricker suggested that resin-modified glass ionomer cement (RMGIC) and conventional glass ionomer cement (GIC) are preferred adhesives over modified composite for the cementation of orthodontic molar bands because of the protection against microleakage at the enamel-cement interface, also suggested that adhesion of GIC to enamel is through an iron-enriched layer that prevents microleakage and decreases failure rate.[4]

Since vitro studies of microleakage are an initial screening method to assess the maximum theoretical loss of sealing ability in vivo,[5] the aim of the present study is to evaluate and compare the microleakage patterns of conventional GIC and RMGIC at the cement-band and cement-enamel interfaces. Our null hypothesis assumed that there were no statistically significant differences in microleakage of these band types of cement.

 Materials and Methods



Forty extracted primary molar teeth without caries were selected (therapeutically extracted in cases of pre-shedding mobility and retained teeth) after the debridement of remaining soft tissue with a periodontal scaler, teeth were placed in distilled water and stored in a refrigerator for a period of 4 weeks, as advised by the International Organization for Standardization (1994).

Teeth were randomly divided into two experimental groups of 20 teeth each.

Group I-Conventional GIC (Fuji I, GC Corporation, Tokyo, Japan)Group II-RMGIC (Fuji Plus, GC Corporation, Tokyo, Japan)

The teeth were then cleaned with pumice, rinsed in distilled water, and dried thoroughly in a stream of air. Optimally sized, clinically adapted stainless steel preformed bands (Libral Traders Pvt Ltd, New Delhi, India) were selected and fitted according to tooth size and morphology. Ten bands were cemented with each of the two types of cement. The manufacturer's instructions were followed for both the cement. To standardize specimen preparation, band selection and cementation were done by a single operator.

Group I had Fuji I powder and liquid mixed and then applied directly to the fitting surface of each band. After band placement, the excess cement was removed with dry cotton rolls. The Fuji I was allowed to bench cure for 5 min after band cementation.

Group II had Fuji plus powder and liquid mixed and then applied directly to the fitting surface of each band. After band placement, the excess cement was removed with dry cotton rolls. The Fuji plus was allowed to bench cure for 5 min after band cementation.

All specimens were then placed in distilled water for 24 h before measuring microleakage. Then, the tooth apices were sealed with sticky wax to prevent dye penetration through the tooth apices. After that, the teeth were rinsed in tap water and air-dried, and nail varnish was applied to the entire surface of the tooth except for approximately 1 mm from the bands. To minimize dehydration of the specimens, the teeth were replaced in water as soon as the nail polish dried. The teeth were immersed in 0.5% solution of basic fuchsin for 24 h at room temperature. After removal from the solution, the teeth were rinsed in tap water, the superficial dye was removed with a brush, and the teeth were dried and embedded in self-curing acrylic up to the occlusal surface of the band.

Evaluation of microleakage

Teeth were separated into two parts through the mesiodistal direction. Four parallel longitudinal sections from the middle part of each molar were made at the occlusobuccal and occlusolingual surfaces with a low-speed diamond disc in the buccolingual direction. The specimens were evaluated with a stereomicroscope (10 times magnification) (SZ 40, Olympus, Tokyo, Japan) for dye penetration along the cement-band and cement-enamel interface. Each section was scored from both the buccal and lingual margins of the bands between the cement-band and cement-enamel interfaces. Microleakage was measured directly by an electronic digital caliper (GSA image analyzer) and the values were recorded.

Statistical analysis

For the cement-band and cement-enamel interfaces, the microleakage scores were obtained by calculating the buccal and lingual microleakage scores. Statistical evaluation of microleakage values between the groups was performed with nonparametric tests (Kruskal-Wallis and Mann-Whitney U tests).

 Results



In the present study, the mean microleakage at buccal and lingual sides for conventional GIC was 2.28 mm and 2.53 mm at the cement-band interface and 2.31 mm and 1.99 mm at the cement-enamel interface [Table 1]. The mean microleakage at buccal and lingual sides for RMGIC was 0.50 mm and 0.38 mm at the cement-band interface and 0.48 mm and 0.44 mm at the cement-enamel interface [Table 2]. Buccal and lingual microleakage comparisons between cement-band and cement-enamel interfaces for both the groups were found to be similar and statistically not significant.{Table 1}{Table 2}

The mean microleakage value for conventional GIC (Fuji I) at cement-band and cement-enamel interfaces was 2.41 mm and 2.15 mm. The mean microleakage value for RMGIC (Fuji Plus) at cement-band and cement-enamel interfaces was 0.44 mm and 0.46 mm. Compared to conventional GIC, RMGIC showed less microleakage at both cement-band and cement-enamel interfaces. P < 0.001 and it was statistically highly significant [Table 3] and [Table 4]{Table 3}{Table 4}

[Figure 1] shows the stereomicroscopic image of GIC and [Figure 2] shows the stereomicroscopic image of RMGIC.{Figure 1}{Figure 2}

 Discussion



Microleakage had been a problem with most GICs even though the material was capable of bonding to the tooth structure.[6] Microleakage is defined as a dynamic phenomenon, clinically undetectable penetration of fluid, bacteria, molecules, and ions between the tooth and restorative material.[7] Microleakage occurring at the tooth-cement interface was considered as a greater biological significance in comparison to the one occurring on the cement-restoration interface because it leads to the development of secondary caries, postoperative sensitivity, inflammation, and necrosis of the pulp.[7]

The present in-vitro study was conducted to evaluate and compare the microleakage patterns of conventional GIC (Fuji I) and RMGIC (Fuji Plus) for band cementation in primary molars using dye penetration method.

Previous studies have assessed the microleakage at the cement-enamel and cement-band interfaces in relation to banded permanent teeth,[4] but in dental literature, there were no studies that had assessed the microleakage in relation to banded primary teeth.

Comparisons of the composition and morphology in primary and permanent teeth show some differences. Primary tooth enamel had a much higher organic content, with a concomitant lower mineral composition than that of permanent tooth enamel. Primary tooth enamel was quite thin, and demineralization might progress through the dentinoenamel junction into dentin more rapidly than with permanent teeth.[8] Thus, in the present study, 40 caries-free mandibular second primary molars were used.

Fricker (1997) suggested that RMGIC and conventional GIC were preferred adhesives over modified composite for the cementation of orthodontic molar bands because of the protection against microleakage at the enamel-cement interface and also suggested that adhesion of GICs to enamel was through an ion-enriched layer that prevents microleakage.[9] Thus, in the present study, conventional GIC (Fuji I) and RMGIC (Fuji Plus) were used.

Several techniques have been introduced to assess microleakage around dental restorations. Dye penetration was a commonly used methodology in restorative dentistry[10],[11] because it provides a simple, relatively cheap, quantitative, and comparable method of evaluating the performance of the various techniques. This methodology involved the exposure of samples to a dye solution and then cross-sections were viewed under a light microscope.[12],[13] To evaluate the relevance of a leakage test, the effective size of oral bacteria must be considered. Because of the range in bacteria sizes, dyes such as methylene blue and fuchsin were realistic agents for determining the sealing ability of the tested materials.[4] Thus, 0.5% basic fuchsin dye was used.

Usually, the assessment was made only at the mid-buccal aspect of each tooth according to the method of Gillgrass et al. (1999).[14] They chose this site because it was readily identifiable on each specimen and bands often loosen at this site, probably because of masticatory loading over the welded buccal attachments.[14] Microleakage, however, might not be similar on both sides on a banded tooth, although studies in restorative dentistry had assumed that assessment of one side represented the whole tooth. Airlocks in the marginal gap, leaching of water-soluble tracers during processing and the failure of only a few sections to allow interpretation of the full pattern limit dye penetration tests to low reproducibility and precision.[15] Thus, assessments were made from four parallel longitudinal sections through the buccal and lingual surfaces in the buccolingual direction according to the methods of Uysal et al. (2010)[4] between the cement-band and cement-enamel interfaces. The mean of the four buccal section values gave the buccal microleakage value and the mean of the lingual values gave the lingual microleakage value.

In the literature, different failure sides for bands were reported.[3],[8],[9],[16] Millett et al. (2003)[16] and Prabhakar et al. (2010)[8] indicated that bands cemented with modified-composite failed predominantly at the enamel-cement interface, whereas failures at both the cement-band and enamel-cement interfaces were observed for RMGIC and conventional GIC specimens. Thus, from the microleakage point of view, evaluations in the present study were performed for both the types of cement from two interfaces: cement-band and cement enamel. Microleakage at the cement-band interface might play a role in band failure caused by adhesion degradation. However, the cement-enamel interface was more critical because it can also cause white spot lesions.[8],[17]

In restorative dentistry, thermal cycles were widely used to simulate temperature changes in the mouth, generating successive thermal stresses at the tooth-resin interface. Kubo et al. (2001)[18] investigated the microleakage of self-etching primers after thermal and flexural load cycling and found that the marginal integrity of self-etching primers did not deteriorate even after thermal cycles (5,000–10,000 cycles) and flexural loads. Similarly, several researchers indicated that more thermal cycles were not related to increased microleakage of restorations.[18],[19] Therefore, thermal cycling was not done in the present study.

Enamel decalcifications could be caused by retained bacterial plaque on the enamel for a prolonged period.[20] Although the areas around an orthodontic band were critical, the areas under the band also need attention. Microleakage under an orthodontic band could increase the patient's risk of decalcification. One of the most effective agents in caries prevention was fluorides because it inhibits caries formation and encourages remineralization of porous enamel and softened dentin.[21] In addition, the general use of dental materials that released fluoride was advised for luting bands in orthodontic practice.[22] Several studies showed the bond strengths of RMGIC and GIC, none had evaluated and compared the microleakage of bands cemented with RMGIC and conventional GIC in primary teeth.[3],[8],[23],[24],[25] Thus, microleakage of bands cemented with RMGIC and conventional GIC in 40 caries-free mandibular second primary molars were compared.

A stainless steel band exhibiting varying degrees of fit and flexibility was cemented to an irregularly shaped tooth crown. The irregular space between the crown and the band was filled with cement that was exposed to the oral environment.[26] Thus, both sides were studied to evaluate the possible effects of cement thickness on marginal leakage.

In the present study, the mean microleakage at buccal and lingual sides for conventional GIC was 2.28 mm and 2.53 mm at the cement-band interface and 2.31 mm and 1.99 mm at the cement-enamel interface. The mean microleakage at buccal and lingual sides for RMGIC was 0.50 mm and 0.38 mm at the cement-band interface and 0.48 mm and 0.44 mm at the cement-enamel interface. Buccal and Lingual microleakage comparisons between cement-band and cement-enamel interfaces for both the groups were found to be similar and statistically not significant. The present study result was similar to the study done by Uysal et al., (2010)[4] this might be due to the uniform thickness of luting cement between band and enamel surface.

In the present study, the mean microleakage value for conventional GIC (Fuji I) at cement-band and cement-enamel interfaces was 2.41 mm and 2.15 mm. The mean microleakage value for RMGIC (Fuji Plus) at cement-band and cement-enamel interfaces was 0.44 mm and 0.46 mm. Compared to conventional GIC, RMGIC showed less microleakage at both cement-band and cement-enamel interfaces. P < 0.001 and it was statistically highly significant.

The present study results were similar to the study done by Uysal et al. (2010)[4] in which they compared microleakage patterns of conventional GIC, RMGIC, and polyacid-modified composite for band cementation and found statistically significant microleakage differences between Ketac-Cem (GIC) and Multi-Cure (RMGIC) P < 0.001.[4] Similarly, Enan et al. (2013)[27] found that bands cemented with GIC showed more microleakage than nano-hydroxyapatite-modified GIC. Hallett and Garcia-Godoy (1993)[28] found that RMGIC (Photac Fil) restorative material showed significantly less microleakage against enamel and dentin/cementum compared to the conventional GIC (Ketac Fil) restorative material.

A possible reason for the present finding could be RMGIC are capable of undergoing a hygroscopic expansion of up to 6% at 24 h[5],[14] which might counteract any tendency to microleakage.[6] The presence of 2-hydroxyethyl methacrylate (HEMA) seems to be a major contributory factor.[29] Reduced setting stress due to water absorption[30] and improved bonding ability or setting during water storage might account in part for the significance in microleakage observed between the two types of cement tested in the present study.

In contrast, Gillgrass et al. (1999)[14] found no significant difference between the cement groups in relation to microleakage at the cement-enamel interface (P > 0.05). The possible reason for their finding could be that resin-modified GICs undergoes greater setting contraction than conventional GICs.

In the present study, conventional GIC showed significantly less microleakage at the cement-enamel interface 2.15 mm than the cement-band interface 2.41 mm. This might be due to the adhesion of GICs to enamel through an ion enriched layer that prevented microleakage, the polyacrylate ions within the cement strongly integrated with and irreversibly attached to hydroxyapatite, displacing phosphate and calcium ions.[31]

Dye penetration was correlated with the degree of enamel demineralization caused by acid incubation.[32]

Kashani et al. (2012)[33] found that RMGIC significantly prevented enamel demineralization adjacent to orthodontic bands compared to zinc polycarboxylate and GIC. Similarly, Prabhakar et al. (2010)[8] stated RMGIC cement was the best adhesive cement when compared to GIC and resin cement for banding space maintainers.

The present study finding also suggests the use of RMGIC instead of conventional GIC for a banding space maintainer. This recommendation was further supported by their favorable handling properties including longer working time, improved resistance to aqueous attack, and increased bond strength.[8],[34]

 Conclusion



Within the limitations of the present study, it could be concluded that bands cemented with RMGIC had significantly less microleakage between the cement-band and cement-enamel interfaces than conventional GIC; thus, RMGIC is better adhesive cement when compared to conventional GIC for cementing bands in primary molars.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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