|Year : 2017 | Volume
| Issue : 3 | Page : 238-243
Comparative evaluation of microleakage between bulk esthetic materials versus resin-modified glass ionomer to restore Class II cavities in primary molars
Vellore Kannan Gopinath
Department of Preventive and Restorative Dentistry, College of Dental Medicine, University of Sharjah, Sharjah, United Arab Emirates
|Date of Web Publication||31-Jul-2017|
Vellore Kannan Gopinath
Department of Preventive and Restorative Dentistry, College of Dental Medicine, University of Sharjah, P. O. Box: 27272, Sharjah
United Arab Emirates
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aim: The aim of the study was to assess the microleakage of one high-viscosity conventional glass ionomer cement (GIC) and a bulk-fill composite resin, in comparison to a resin-modified GIC in Class II restorations in primary molars. Materials and Method: Standardized Class II slot cavity preparations were prepared in exfoliating primary molars. Teeth were restored using one of the three materials tested (n = 10): SonicFill bulk-fill composite resin (SF), EQUIA Fil conventional reinforced GIC (EQF), and Vitremer resin-reinforced GIC (VT). The restorations were then subjected to thermocycling procedure (×2000 5°C–55°C 10 s/min) and soaked in 1% neutralized fuchsin solution (pH: 7.4) for 24 h at 37°C. Teeth were sectioned longitudinally in a mesiodistal direction under continuous cooling into three slabs of 1 mm thickness and studied under a stereomicroscope for dye penetration. Statistical Analysis: Data were evaluated by one-way analysis of variance and the Tukey's multiple comparison test employing 95% (α = 0.05). Results: EQF and SF showed significantly lower microleakage scores and percentage of dye penetration (%RL) when compared to VT resin-reinforced GIC (P < 0.001). Conclusion: SF and EQF produced the minimum microleakage when compared to VT in Class II restorations on primary molars. Fewer application procedures and reduction in treatment time in SF and EQF systems proved advantageous in pediatric dentistry.
Keywords: Bulk-fill composite, Class II cavities, glass ionomer cement, microleakage, primary molar, resin-reinforced glass ionomer cement
|How to cite this article:|
Gopinath VK. Comparative evaluation of microleakage between bulk esthetic materials versus resin-modified glass ionomer to restore Class II cavities in primary molars. J Indian Soc Pedod Prev Dent 2017;35:238-43
|How to cite this URL:|
Gopinath VK. Comparative evaluation of microleakage between bulk esthetic materials versus resin-modified glass ionomer to restore Class II cavities in primary molars. J Indian Soc Pedod Prev Dent [serial online] 2017 [cited 2019 Mar 22];35:238-43. Available from: http://www.jisppd.com/text.asp?2017/35/3/238/211842
| Introduction|| |
In view of the anatomic and histological differences unique to primary teeth, the restorative material selected should last the lifetime of the teeth. Materials used for restoring decayed primary teeth with conservative tooth preparations should function in mastication with adequate esthetics. The qualities of the material should demonstrate adequate strength, adaptability, marginal integrity, and good color match. Factors such as moisture tolerance, bulk fill, and one-step application are advantageous when treating young children. Restorative materials with easier procedures and faster application steps that reduce treatment time, especially in pediatric dentistry were used in this study. Due to ease of use and acceptable esthetics, glass ionomer cement (GIC) and composite resin restorative materials have been widely advocated for restoring posterior primary teeth. The choice of restorative material must be based on the performance of the material under simulated and clinical conditions.
In spite of the improvements in adhesive restorative materials, poor adaptation and microleakage remain a major reason for failure in dental restoration. Restorative materials regularly used in posterior primary teeth include composite resin, GICs, and resin-modified GICs (RMGICs). These materials undergo dimensional changes when placed in the prepared cavity as a result of placement techniques and due to variations in the oral environment. Henceforth, the ability of the restorative material to effectively sustain oral conditions depends on the retentive ability of the material to seal the cavity against the ingress of oral fluids and microorganism. Poor marginal sealing of the restoration results in the passage of bacteria, fluids, and molecular penetration between the cavity and restorative material interface. Microleakage at the interface of the cavity wall and restoration results in hypersensitivity of the restored teeth, discoloration, recurrent caries, and pulpal injury leading to the failure of restoration. Microleakage of posterior restorative materials at the margins of the proximal box specifically at the gingival floor of Class II restorations is a matter of concern to the clinician.
It is vital that recently developed restorative materials possess improved physical and mechanical properties, as well as effectively seal the cavity restoration margin, thereby accelerating the performance of restorative materials under oral conditions. One purpose of this study was to assess the microleakage of one high-viscosity conventional GIC and a bulk-fill composite resin, in comparison to a RMGIC in Class II restorations in primary molars. The testing hypothesis maintained that no statistically significant differences are present between the materials tested.
| Materials and Methods|| |
In this study, one bulk-fill composite resin, one high-viscosity bulk conventional GIC, and RMGIC were evaluated. Names, codes, manufacturers, mixing, and application procedures of the materials tested are summarized in [Table 1]. Thirty exfoliating primary second molars with intact marginal ridge were collected for this experiment, with consent from the patient's parents, approved by the Ethical and Research Committee of the University of Sharjah protocol (141014). The teeth were stored in 0.5% chloramine-T at 4°C and used within 1 month. The crowns of the teeth were thoroughly cleaned with cleaning paste and a Prophy brush and rinsed with copious amounts of tap water before cavity preparation.
|Table 1: Names, codes, manufacturers, and application steps of tested adhesives|
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One standardized occlusal slot Class II cavity was prepared at the intact site of each tooth with standardized dimensions of 3.0 mm facio-lingually, 1.5 mesiodistally, and 3.0 mm occluso-gingivally, using tungsten carbide burs (#329 Maillefer, Ballaigues, Switzerland). It was then finished with fine diamonds (Busch, Engelskirchen, Germany) placed in an air-rotor handpiece driven by a parallelograph under constant water cooling. The cavity dimensions were verified by a digital caliper (accuracy ± 0.25 mm). The bur was replaced after every three preparations. The teeth were randomly divided into three experimental groups (n = 10). Each group was assigned to one of the three materials tested. Shade selected for all materials was A3. A clear Mylar Matrix Strip (Patterson Dental Supply, USA) was applied to the proximal surface and kept firm in place with a metal paper clip applied on the buccal and lingual surfaces of the specimen. Materials were mixed as per the manufacturers' recommendations and immediately dispensed in the cavities on a single layer. In all cases, material extrusion began at the deepest part of the cavity and care was exerted to avoid separation of the capsule nozzle from the extruding material mass, to avoid porosity. Contouring of the material was performed immediately after packing with a smooth plastic instrument. Light-cured materials were polymerized as per the manufacturers' instructions with a light-emitting diode (LED) curing unit (Bluephase G2, Ivoclar Vivadent, Schaan, Liechtenstein) emitting 1200 mW/cm2 light intensity as measured with a LED curing radiometer (Bluephase Meter, Ivoclar Vivadent). Once set (10 min after activation), the restorations were finished with superfine diamond burs (Busch, Engelskirchen, Germany) under continuous water spray and polished with the enhance polishing system (De Trey Dentsply).
The apices of the teeth were sealed with RMGIC (Fuji II LC, GC America Inc., Alsip, IL, USA). The restored teeth were stored for 1 week in water at 37°C and then thermal-cycled (×2000 5°C–55°C 10 s/min). The entire surface of each specimen was then covered with two coats of varnish up to a 1 mm area from the restoration margins. The teeth were soaked in 1% neutralized fuchsin solution (pH: 7.4) for 24 h at 37°C. After the immersion period, the teeth were rinsed with water; the crowns were removed from the roots using a diamond bur attached to a high-speed handpiece, embedded in epoxy resin, and longitudinally sectioned in a microtome (Buehler IsoMet) in a mesiodistal direction under continuous cooling into three slabs of 1 mm thickness. Sections were polished with a sequence of silicon carbide papers (320, 400, 800, and 1000), followed by felt impregnated with 1 and 0.25 μm grit diamond slurry used in an automatic polishing machine. Between each granulation and at the end, the specimens were cleaned and immersed in water in an ultrasonic bath. Adaptation to the enamel walls and dye penetration were assessed under a stereomicroscope (DM 4000B, Leica) at ×60 magnification. The score criteria were: Score 0: perfect adaptation/no dye penetration; Score 1: gaps and microleakage up in enamel not exceeding to dentin walls depth from the margins toward the axial wall; Score 2: dye penetration exceeding to dentinal walls of the gingival wall without reaching the axial wall; Score 3: dye penetration reaching the axial wall. Dye penetration at the tooth/restoration interface at gingival margin of each slab was measured in millimeters, and mean dye penetration of each tooth was calculated from the average readings of the two slabs. The extent of dye penetration was evaluated by linear measurements (RL) and expressed in percentage (%RL). The results of dye penetration scores and measurements of the percentage of dye penetration (%RL) were analyzed by one-way analysis of variance and Tukey's multiple comparison test employing 95% (α = 0.05) level of significance for all comparisons. Both analyses were carried out by SigmaPlot (version 12.3) software (Systat Software Inc., San Jose, CA, USA).
| Results|| |
The microleakage scores and dye penetration percentages (%RL) indicated that RMGIC (Vitremer [VT]) showed significantly higher values when compared with bulk-fill composite resin (SonicFill [SF]) and high-viscosity bulk conventional GIC (EQUIA Fil [EQF]) [Figure 1], [Figure 2], [Figure 3] (P < 0.001). It was observed that when SF and EQF were compared, SF had the least microleakage scores, whereas EQF scored slightly higher. However, no significant difference was noted between SF and EQF [Table 2]. Bulk-fill composite resin (SF) and high-viscosity bulk conventional GIC (EQF) showed the best results with the mean microleakage score value of <1, whereas RMGIC (VT) showed a mean score value of more than 2.
|Table 2: The mean and standard deviation for dye penetration scores and the percentage of dye of dye penetration (%RL)|
Click here to view
| Discussion|| |
The present study assessed microleakage of dental restorative materials in Class II cavities of primary molars. RMGIC (Vitremer, 3M, St. Paul, USA) were compared with high-viscosity conventional GIC (EQUIA Fil, GC, USA) and a bulk-fill composite resin (SonicFill, Kerr, CA, USA). RMGIC (VT) has been widely used to restore Class II cavities in primary molars with reasonable success., Hence, a controlled study comparing newer materials such as high-viscosity conventional GIC (EQF) and bulk-fill composite resin (SF) were included in this study. EQF is a new generation glass ionomer for one-step posterior restoration with easy handling and excellent esthetics. Resin coating (EQUIA coat) optimizes its physical properties. It is easy and convenient to place, self-adhesive with no bonding steps. The inclusion of EQF in the experimental group was based on a clinical trial which evaluated its performance with microfilled hybrid composite (GC Gradia Direct posterior) on Class II cavity revealing similar clinical success over a period of 4 years. Whereas SF in the experimental group has been tested in vitro, the inclusion of this material in the present study was based on its bulk-fill property and innovative material delivery system utilizing KaVo handpiece that enabled sonic activation reducing the composite's viscosity to fill the cavity rapidly. Therefore, time spent on placement, packing, and sculpting the restoration was reduced, which proved advantageous when treating fidgety young children.
The microleakage of restorative materials necessitates further evaluation, as inadequate interfacial adaptation and low-quality marginal seal causes leakage, recurrent caries, and pulpal irritation., A high-quality marginal seal aids the performance of restoration. The extent of dye penetration was evaluated by linear measurements usually performed by direct assessment of the outer restorative margins using reflection optical microscopy, confocal microscopy, and environmental scanning electron microscopy. Indirect assessment involves evaluation of the interfacial dye penetration or contract agents in microleakage studies.
The marginal seal of restorative materials to the cavity walls depends on two variables., The first refers to material properties such as the type of adhesive, polymerization shrinkage, viscoelasticity, and stiffness of material. The second refers to individual treatment conditions which include cavity size, geometry, restorative placement, and curing techniques. The clinical implication of microleakage is related to discomfort in conjunction with occlusal forces, which may be attributed to fluid accumulation within the gap and the subsequent fluid movement within the tubules. The results of the present study demonstrate significant differences in microleakage between RMGIC (Vitremer, 3M, St. Paul, USA) when compared with high-viscosity conventional GIC (EQUIA Fil, GC, USA) and a bulk-fill composite resin (SonicFill, Kerr, CA, USA). Consequently, the hypothesis testing was rejected.
The rationale for the differences noted in the present study between the systems tested could be attributed to the variance in materials tested and their handling characteristics. Cavity size and geometry cannot be considered as a variable in the present study that used an air-rotor handpiece driven by a parallelograph and verified cavity dimensions with a digital caliper (accuracy ± 0.25 mm). A precise adaptation of the restorative material to the walls of the cavity and proper marginal seal is considered mandatory for the longevity of restoration. However, the present study detected the percentage of dye penetration values (%RL), and dye penetration scores were highest in RMGI (Vitremer, 3M ESPE, USA) compared to conventional glass ionomer (EQUIA Fil, GC, Japan) and bulk-fill composite (SonicFill, Kerr, USA). Similarly, other in vitro studies showed that high-viscosity glass ionomer has significantly less microleakage when compared to nano-filled RMGI.
Although microleakage scores and the percentage of dye penetration values of high-viscosity conventional GIC (EQUIA Fil, GC, USA) were significantly lower than VT, they differed little from bulk-fill composite (SonicFill, Kerr, USA). Therefore, indicating that both materials have minimal microleakage. The findings were in correlation with another study that compared high-viscosity glass ionomer restorative materials (EQUIA Fil, GC, USA) with resin composites (VOCO, Germany) that also exhibited similar microleakage scores such as those observed in our present study. Since our trials of high-viscosity conventional GIC (EQUIA Fil) required fewer application steps minimizing microleakage comparable to bulk-fill composite (SF), it appeared to be better suited for younger patients, unable to remain still during treatment. Further studies concerning the strength of the restorative material would be beneficial.
The bulk-fill composite resin with innovative sonic activation which reduced the viscosity of the material showed the least microleakage in the present experiment. Favorable marginal adaptation noted in the bulk-fill composite (SonicFill, Kerr, USA) may be attributed to the adhesive system used,, and the enhanced viscoelastic properties  of the material tested utilizing sonic activation and delivery system. The present study revealed that bulk-fill composite (SonicFill, Kerr, USA) formed a good marginal seal among the systems tested. A related microleakage study where Class II cavities were restored with sonic/bulk-fill and Herculite Ultra/incremental fill showed similar mean microleakage scores. SonicFill (Kerr, USA) demonstrated optimal handling features, reduced operating time, and favorable marginal seal, leading to the success of this restorative material in the clinical environment. Both these factors are valuable in pediatric dentistry. Accordingly, the long-term effects of the restorative materials in oral environments must be monitored. It is worth noting that further studies utilizing advanced micro-XCT methods to assess interfacial gap could support the findings of this present work.
| Conclusion|| |
When compared to RMGIC (VT), bulk-fill composite resin (SF) and high-viscosity bulk conventional GIC (EQF) utilized in this study produced significantly less microleakage. In addition, fewer application procedures and reduced treatment time in SF and EQF systems are especially advantageous in pediatric dentistry where younger patients get easily agitated. The combination of these benefits and other results enumerated above may prove valuable to the dental profession.
This project was supported by the College of Graduate Studies and Research, University of Sharjah, Sharjah, UAE (grant no. 141014).
Financial support and sponsorship
This project was supported by the College of Graduate Studies and Research, University of Sharjah, Sharjah, UAE (grant no. 141014).
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]