|Year : 2019 | Volume
| Issue : 4 | Page : 200-204
A comparative evaluation of the marginal sealing ability and compressive strength of different restorative materials – Type VII glass-ionomer cement, Type IX glass-ionomer cement, and intermediate restorative material: An in-vitro study
S Rajakumar, R Kavitha, MP Revanth
Department of Pedodontics and Preventive Dentistry, SRM Kattankulathur Dental College and Hospital, Kanchipuram, Tamil Nadu, India
|Date of Submission||07-May-2019|
|Date of Acceptance||17-Oct-2019|
|Date of Web Publication||22-Jan-2020|
Dr. S Rajakumar
Department of pedodontics and preventive dentistry, No . 22/12 Vedagiri Street, Alandur, Chennai - 600 016, Tamil Nadu
Aim: The aim of this in vitro study is to assess and to comparatively evaluate the marginal sealing ability and the compressive strength between type VII GIC, type IX GIC and IRM. Materials and Methodology: Class I cavities were made on a total of 30 extracted and preserved premolars and restored with type VII GIC, type IX GIC and IRM (3 groups of 10 samples each). Samples were thermocycled, stained with 2% gentian violet dye, sectioned bucco-lingually and scored for microleakage under Stereo-Zoom microscope and results were statistically evaluated. 30 Cylindrical shaped moulds were taken and restored with Type VII GIC, Type IX GIC and IRM.(3 groups of 10 specimens each) . The specimens were tested for compressive strength by mounting them on Universal testing machine. Results: The comparison of the performance between the three groups showed a statistically significant difference. P< 0.05 were considered to be significant values. Conclusion: In this study, Type IX GIC showed the least microleakage and high compressive strength when compared to the other two restorative cements. This in-vitro study needs a proper clinical investigation to be applied as a clinical long-term study to overcome the lack of exact oral environmental reflections.
Keywords: Compressive strength, glass-ionomer cement type VII, intermediate restorative material, type IX
|How to cite this article:|
Rajakumar S, Kavitha R, Revanth M P. A comparative evaluation of the marginal sealing ability and compressive strength of different restorative materials – Type VII glass-ionomer cement, Type IX glass-ionomer cement, and intermediate restorative material: An in-vitro study. SRM J Res Dent Sci 2019;10:200-4
|How to cite this URL:|
Rajakumar S, Kavitha R, Revanth M P. A comparative evaluation of the marginal sealing ability and compressive strength of different restorative materials – Type VII glass-ionomer cement, Type IX glass-ionomer cement, and intermediate restorative material: An in-vitro study. SRM J Res Dent Sci [serial online] 2019 [cited 2020 Jul 13];10:200-4. Available from: http://www.srmjrds.in/text.asp?2019/10/4/200/276364
| Introduction|| |
Optimal care to children in an inaccessible area can be achieved by the usage of intermediate restorative material (IRM), which comes under the procedure ofMinimally invasive dentistry, but, yet the usage of glass-ionomer cement (GIC) is inevitable in the field of dentistry after its development by Wilson and Kent in 1972.
However, the usage of GIC in many instances mainly in uncooperative children is restricted due to moisture contamination, prolonged setting time, dehydration, and also due to poor wear resistance and less fracture toughness.
The success of any restorative material depends on its microleakage and bonding strength to the prepared cavity walls, and thus, it is most commonly considered to be the major contributing factor to secondary caries, leading to the failure of restoration and pulpal irritation. Meanwhile, the longevity of any dental restoration mainly depends on the sealing ability and retention of the material to the prepared tooth cavity walls. This sealing ability is mainly affected by polymerization shrinkage which is otherwise called as microleakage.
The retention and sealing ability of the cement can be enhanced by improving the adhesive mechanism of the cement which in turn prevents microleakage, thus by minimizing the microleakage secondary caries formation can be prevented along the cement tooth interface.
On the other hand, limitations of any kind of restorative material include the brittleness and poor fracture resistance of the materials. Thus, determining the compressive strength of the material plays a vital role which determines the mechanical properties of the cement.
Thus, the objective of this in-vitro study was to assess and comparatively evaluate the marginal sealing ability and the compressive strength between Type VII GIC, Type IX GIC, and IRM.
| Materials and Methodology|| |
Sample preparation for microleakage
Thirty intact, caries-free human premolar teeth freshly extracted for orthodontic purposes were selected for the study. The selected teeth were also free from cracks and restorations. Prior to the usage of the tooth, informed consent was obtained from the individual from whom the tooth was extracted. After surface debridement with hand scaling instruments, the teeth were cleaned with pumice and stored in normal saline.
A standardized G. V. Black's Class I cavity preparation was done in all 30 extracted premolars of 2-mm occlusogingival depth and 3-mm mesiodistal width using a water cooled, high-speed handpiece and fissure diamond bur which were divided into three groups and restoration was done following the manufacturer's instruction using Type VII GIC, Type IX GIC, and IRM. The tooth with a prepared cavity was well cleaned using slurry of pumice powder with a polishing rubber cup. Later, each group was restored with a different restorative material according to the manufacturer's instruction and randomly divided as follows.
- Group I: Ten teeth to be restored with Type VII GIC
- Group II: Ten teeth to be restored with Type IX GIC
- Group III: Ten teeth to be restored with Type IRM.
After restoration, the teeth were subjected to finishing and polishing and were stored in de-ionized water at 37°C for 24 h.
Each tooth of both the groups was then individually subjected to thermocycling at various temperatures such as 5°C, 37°C, and 55°C for 250 cycles, each with an interval of 30 s, and then stored in distilled water for 24 h to prevent dehydration, before testing for microleakage., The purpose of thermocycling is to simulate the oral environment.
The tooth root apices were sealed using light-cured composite material to prevent any dye penetration through the apices during the procedure and also to avoid false-positive results. Later, all the prepared teeth were coated with nail varnish around the restoration except 1–2 mm left around the margins to limit the dye penetration into the margins of the prepared and sealed cavity. The prepared tooth was left to dry out completely. Then, the tooth was immersed in 2% gentian violet for 24 h. After 24 h, the coronal portion of the specimens was sectioned and mounted on acrylic blocks; all the mounted blocks were sectioned (buccolingually) from the middle and split into mesial and distal parts, which were observed under a stereo-zoom microscope to evaluate the microleakage.
The images were captured using Qcapture pro 7 software (Teledyne Qimaging, Windows Xp Msp3, Canada), and the scores were given to the tooth obtained samples using the criteria mentioned in[Table 1].
Sample preparation for compressive strength
Thirty cylindrical-shaped molds were taken and divided into three groups:
- Group I: Ten molds to be restored with type VII GIC
- Group II: Ten molds to be restored with type IX GIC
- Group III: Ten molds to be restored with IRM.
Then, the samples were positioned in a universal testing machine, and compressive force was applied with a crosshead speed of 1.0 mm/min, and the values were obtained for the samples in N/m.
The scores were obtained [Table 2] and [Table 3] and were subjected to statistical analysis to consider whether “P” is <0.05 by the Kruskal–Wallis test for the comparative analysis of both microleakage and evaluation of compressive strength between the three different restorative cement. On statistical analysis, the obtained P value is typically <0.05, thus in this study, we reject the null hypothesis and there exists statistical significance (0.0001) differences between the restorative materials used [Table 4] and [Table 5].
|Table 4: Comparison of microleakage scores between three different restorative materials|
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|Table 5: Comparison of compressive strength values between three different restorative materials|
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| Results|| |
On Intergroup comparison of three restorative materials with respect to microleakage [Figure 1], [Figure 2], [Figure 3], [Figure 4] represents the various stages of microleakage) showed a statistically significant difference. The microleakage level was more in group iii (IRM) with the mean value (2.90) and group i(type vii gic) with the mean value(1.00) Whereas, group ii (type ix gic) with the mean value(0.20), Showing the least Microleakage, that is, no microleakage was seen in 80% of the samples in group ii, whereas 50% of samples in group I showed microleakage, all the test samples of group iii showed microleakage, Meanwhile the compressive strength is also higher in group ii followed by group i and least in group iii.
|Figure 1: Representative microscopic image of a tooth with microleakage score 0|
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|Figure 2: Representative microscopic image of a tooth with microleakage score 1|
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|Figure 3: Representative microscopic image of a tooth with microleakage score 2|
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|Figure 4: Representative microscopic image of a tooth with microleakage score 3|
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| Discussion|| |
The principal aim of determining microleakage is to predict the longevity and performance of the restorative material used. Thus, the restorative material which maintains the marginal seal for a long time span and also resists the bacterial fluid infusion in and around the restored cavity decreases clinical problems such as formation of secondary caries and discolorations of the restored material due to caries formation.
The increased bond strength of the restored material and the minimal or no microleakage shows that the dental restorative material has good adhesive effectiveness to the margins of the prepared cavity walls.
The present study was designed to evaluate the marginal sealing ability and compressive strength between three different restorative cements – type VII GIC, type IX GIC, and IRM.
The increased fatigueness of the adhesive interface decreases the bonding performance of the restored material, which, in turn, is because of the heavy mechanical load created by the masticatory forces. An overall view thus indicates that material properties such as thermal expansion and elasticity play a vital role in modifying the marginal sealing ability and also the nonmaterial-related factors such as cavity preparation, material application technique, also to be taken into account as well, for the better resistance and retention of the material to the tooth interface. The marginal adaptation of any restorative material with good sealing ability prevents maximum microleakage. The restorative material and the tooth interface should have identical thermal expansion to limit microleakage. To simulate the original oral environment, thermal stresses are usually employed by thermocycling on the tooth restoration at different degrees and different rates. In this study, to produce a dynamic oral environment, the GIC- and IRM-restored teeth were subjected to thermal changes through thermocycling. Thermal cycles ranging between 200 and 1000 were used in some studies. In the present study, 500 thermal cycles were used. In this study, stereo zoom microscope was used to determine the dye penetration between the scales of 0 and 3 for the qualitative measurement of the sectioned specimens; further assessment is done using simple microscope, which is widely accepted and most preferred method, which effectively reveals the microleakage.
Intergroup comparison of three restorative materials with respect to microleakage showed a statistically significant difference (P = 0.0001) by the Kruskal–Wallis test. The microleakage level was high in Group III (IRM), with a mean value of 2.90, and in Group I (Type VII GIC), with a mean value of 1.00, whereas Group II (Type IX GIC) with a mean value of 0.20 showed the least microleakage, that is, no microleakage was seen in 80% of the samples in Group II, whereas Group I and Group III showed that only 50% and 0% had no microleakage, respectively.
The fracture resistance of the restorative material has specific resistance called fracture stress, exceeding of which can result in fracture of the restored material And in turn results in increased microleakage. Thus, the compressive strength of the restorative material placed into the cavity walls plays a vital role mainly during the application of masticatory forces, while increase of the compressive strength can be analyzed by the setting reaction of the restorative cements used.
In a study conducted to compare the compressive strength and diametral tensile strengths of GICs with that of amalgam and composite resin, the compressive strength of GIC was found to be lower (83.39–147.93 MPa) than that of the compressive strength of amalgam (300–450 MPa) and composite resin (210–340 MPa), and it was concluded that the compressive strength of amalgam is higher.
Compressive stresses contribute to fracture or failure through masticatory forces, although an exact critical value is unknown. According to British specification, 125 MPa is considered as a minimal value to resist the normal masticatory force commonly used by humans, whereas some authors believe that this value should be 100 MPa in primary dentition.
In this study, high compressive strength between the three different cements was compared and analyzed by the Kruskal–Wallis test which showed a statistically significant difference (P = 0.0001). Group II (Type IX GIC) exhibited the greater compressive strength, with a mean value of 171.73 N/mm2, when compared to Group I (Type VII GIC) and Group III (IRM), with mean values of 123.63 N/mm2 and 105.63 N/mm2, respectively.
| Conclusion|| |
In this study, Group II (Type IX GIC) showed the least microleakage and high compressive strength when compared to the other two restorative cements – Group I (Type VII GIC) and Group III (IRM). This in-vitro study needs a proper clinical investigation to be applied as a clinical long-term study to overcome the lack of exact oral environmental reflections.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]