| Abstract|| |
Aim: The aim of the study is to compare the microleakage of three different direct restorative materials (amalgam [AA], glass ionomer cements [GICs], and Cention N [CN]) in Class II restorations using stereomicroscope. Materials and Methods: A standardized Class II cavity preparation was made involving the proximal and occlusal surfaces. All prepared samples were randomly divided into 3 experimental groups, with 10 teeth each according to the restoration material used: Group I-AA; Group II-GICs; and Group III-CN. The restored teeth were stored for 24 h in distilled water and thermocycled for 500 cycles between 5°C and 55°C with a dwell time of 30 s in each bath. Samples were immersed in 0.5% basic fuchsin dye for 24 h. The teeth were sectioned along the mesiodistal direction. The dye penetration of the occlusal and gingival margins of each section was evaluated independently by the observer using a stereomicroscope. Results: Statistical analysis revealed lower microleakage scores in GIC and CN. Higher microleakage was observed in Group AA. Mean microleakage score of Group-I (AA) was the highest of all groups. Mean microleakage score of Group-III (CN) was the lowest of all groups. As per the critical differences (CD), the mean microleakage score of Group-III CN) was significantly lower than that of Group-I (AA), Group-II (GIC) (P < 0.01). There is no significant difference between the mean microleakage score of Group-I (AA) and Group-II (GIC). Conclusion: Out of all the restorative materials, CN a newer restorative material displayed minimum microleakage compared to AA and GICs.
Keywords: Amalgam, Cention N, glass ionomer cement, marginal microleakage
|How to cite this article:|
Mazumdar P, Das A, Das UK. Comparative evaluation of microleakage of three different direct restorative materials (silver amalgam, glass ionomer cement, cention N), in Class II restorations using stereomicroscope: An in vitro study. Indian J Dent Res 2019;30:277-81
|How to cite this URL:|
Mazumdar P, Das A, Das UK. Comparative evaluation of microleakage of three different direct restorative materials (silver amalgam, glass ionomer cement, cention N), in Class II restorations using stereomicroscope: An in vitro study. Indian J Dent Res [serial online] 2019 [cited 2019 Oct 21];30:277-81. Available from: http://www.ijdr.in/text.asp?2019/30/2/277/259227
| Introduction|| |
There have been more changes and developments in dentistry over the past decade than in the previous 100 years combined, and the pace is accelerating. In the current age of adhesive dentistry or microdentistry, conservation of tooth structure is paramount. Rather than using extension for prevention as a treatment guideline, emphasis is now placed on restriction with conviction.
The integrity and durability of the marginal seal are essential for any restorative system to maintain pulpal health and to increase the longevity of the restoration. One of the weak links in Class II restorations is microleakage at the gingival margin of the proximal box which contributes to postoperative sensitivity and high incidence of secondary caries accounting for many clinically failed restorations. Despite attempts aimed at reducing the deficiencies at the interfaces and improvement in material properties substantial microleakage at the gingival margin continues to be reported.
Numerous direct filling materials are available in the modern dental practice from amalgam (AA) to modern tooth color restorative material. AA materials were first introduced in western dentistry in the 19th century, glass ionomer cements (GICs) were introduced around the 1970s, composites became standard during the 1980s, resin-modified glass ionomers and compomers were introduced in the 1990s and the current decade saw the launch of several new restorative materials.
McLean and Wilson first described the open-sandwich technique in 1977, proposing it as a method to improve adhesion of resin composite in cervical area by placing GIC cervically and composite where enamel was sufficient. Thus, GIC acted as a buffer zone minimizing shrinkage at the gingival area.
AA and GICs can be viewed as basic filling materials. Basic in the sense that they are long established, economical, and simple to use. They are usually applied in bulk without an adhesive, are self-curing and do not require complicated dental equipment.
Although the greater development in direct filling materials has been made in recent decades; simple, basic restorative materials such as AA and GICs still remain popular.
Cention N (CN) is an “alkasite” restorative material. Alkasite refers to a new category of filling material, which is like compomer or ormocer materials and is essentially a subgroup of the composite material class. This new category utilizes an alkaline filler, capable of releasing acid-neutralizing ions.
CN is a tooth-colored, basic filling material for direct restorations. It is self-curing with optional additional light curing. CN is available in the tooth shade A2. It is radiopaque and releases fluoride, calcium, and hydroxide ions. As a dual-cured material, it can be used as a full volume (bulk) replacement material. Optional light curing is carried out with blue light in the wavelength range of approximately 400–500 nm – thus, all standard polymerization lights can be used to cure the material.
CN consists of a separately packaged powder and liquid that are mixed by hand directly before use. One scoop of powder is used per 1 drop of liquid, corresponding to a powder/liquid weight ratio of 4.6–1. The liquid comprises of dimethacrylates and initiators, while the powder contains various glass fillers, initiators, and pigments.
The advent of new restorative materials, together with new adhesives has brought enormous benefits notably in terms of esthetics and strides toward minimally invasive dentistry. They may, however, be perceived as expensive, time-consuming, and technique-sensitive. Their existence has not eliminated the need of traditional “basic” dental materials.
This in vitro study compared marginal microleakage in Class II cavities restored with AA, GIC, and CN. Microleakage of occlusal and gingival margins of Class II cavities were evaluated using stereo microscope.
| Materials and Methods|| |
Thirty sound mandibular first molars, with neither carious lesions nor restorations, which were recently extracted, were selected for this in vitro study. Each tooth underwent scaling and root planing with an ultrasonic device to remove residual organic tissue. Then, the teeth were immersed in 2.6% sodium hypochlorite solution and rinsed with running water for 10 min. Each steps were evaluated by a calibrated evaluator.
A standardized Class II cavity preparation was made involving the proximal and occlusal surfaces using number 245 tungsten carbide bur in a high-speed airotor handpiece with water spray. The overall dimension and depth of cavities were standardized (occlusal floor - width 4 mm, length 5 mm; axial wall - width 4 mm, height 3 mm; gingival floor - width 4 mm, depth 2.5 mm). The proximal boxes ended in dentin and the gingival cavosurface margin was given 1 mm above the cementoenamel junction with the cavosurface margins as butt joint
All the prepared samples were divided into 3 experimental groups, with 10 teeth in each group according to the restorative material used: Group I-silver AA; Group II-Type II GIC; and Group III-CN.
The thirty samples so prepared were divided into groups as follows and subjected to experimentation [Figure 1].
- Group I: The silver AA (DPI batch number 2171) was placed in the prepared cavity using the AA carrier and condensed with the help of AA condenser without a liner
- Group II: Type II GIC (GC lot number 1612101) was placed in the prepared cavity using a plastic filling instrument
- Group III: CN (Ivoclar Vivadent lot number V26429) was placed in the prepared cavity using a plastic filling instrument and condensed with the help of a condenser without liner application.
- The restored teeth were stored for 24 h in distilled water and thermocycled for 500 cycles between 5°C and 55°C with a dwell time of 30 s in each bath
- The apices of the specimens were sealed with sticky wax
- All tooth surfaces were covered with two coats of clear nail polish with the exception of 1 mm around the tooth-restoration margins and allowed to air dry
- Samples were immersed in 0.5% basic fuchsin dye for 24 h
- The teeth were sectioned along the mesiodistal direction, coincident with the center of the restoration, with a sectioning diamond disc under water spray from chip syringe
- The dye penetration of the occlusal and gingival margins of each section was evaluated independently by the observer using a stereo-microscope (Olympus, F. No. 19-34/2008-RE) at a magnification of 22.5× and the microleakage of occlusal and gingival margins of Class II cavities were recorded based on the criteria shown in [Table 1] and [Figure 2].
The leakage number was taken from the following ratio:
The leakage distance from the margins to the determined limit was recorded in mm, and the leakage number was a result of the proportion of dye leakage [Table 1].
The scores thus obtained from the samples were then subjected to statistical analysis.
Descriptive statistical analysis was performed to calculate the means with corresponding standard deviation. Furthermore, one-way analysis of variance followed by post hoc Tukey's test was performed with the help of critical difference (CD) or least significant difference at 5% and 1% level of significance to compare the mean values. P < 0.05 was taken to be statistically significant [Figure 3] and [Figure 4].
|Figure 3: Graphical representation of Mean and standard deviation of three groups|
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|Figure 4: Distribution of microleakage score of different restorative materials|
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| Results|| |
According to the Statistical Analysis, lower microleakage scores were observed in CN and GIC. Higher microleakage scores were observed in silver amalgam.
- The mean microleakage score of Group I is higher compared to other groups, and the mean microleakage score of Group III is lowest compared to other groups [Figure 5] and [Figure 6]
- As per the CDs, the mean microleakage score of Group III is significantly lower than Group I and Group II (P = 0.05). The P value is not falling into the confidence interval [Figure 7]
- At an individual level, there is no significant difference in the mean microleakage scores of Group I and Group II. The P = 0.17 which is in the confidence interval of (P > 0.05)
- At an individual level, there is a significant difference in the mean microleakage scores of Group II and Group III. The P = 0.02 which is not in the confidence interval of (P > 0.05)
- At an individual level, there is a significant difference in the mean microleakage scores of Group I and Group III. The P = 0.005 which is not in the confidence interval of (P > 0.05).
| Discussion|| |
Microleakage is still a concern in restorative dentistry, as it has been related to pulp alterations, sensitivity, and secondary caries, which are the most common causes of restoration failure (Manhart et al., 2004). Currently, no outstanding method is available to determine microleakage (Alani and Toh, 1997). Despite the limitations, dye leakage methodology remains a popular tool to investigate the sealing ability of restorative materials, due to its low cost and the technique being very simple (Raskin et al., 2001).
Microleakage refers to the leakage of tiny amounts of fluids and debris in the space between a dental restoration (cement or adhesive) and the tooth (cavity wall) at the surface. Linked to poorly fitting restorations, it may or may not be clinically detectable and is one of the most important reasons for recurrent caries and pulpitis. Marginal microleakage should be considered in the evaluation of a restorative material because it has been directly related to the success or failure of the restorations.
There is a constant search for the material and technique that ensures adhesion to the tooth structure to minimize the leakage potential. Microleakage is used as a measure by which clinicians and researchers can predict the performance of a restorative material.
GICs exhibited the lowest leakage in cementum/dentin margins; similar to findings previously reported (Marchiori et al., 1998; de Morais, Rodrigues Jr and Pimenta, 1999; Cenci et al., 2004). The better performance could be attributed to the high dimensional stability of the material (Culbertson, 2001), lower thermal conductibility and chemical adhesion to dentin.
Although GICs exhibits good performance in cementum/dentin, the material has shown a lower resistance to dissolution caused by acids from the oral environment when compared to composites (Culbertson, 2001). Nevertheless, the release of fluoride to dental structure would increase the mineral content (Osinaga et al., 2003), turning the surface more resistant to acids produced by bacteria, thus, aiding in the prevention of secondary caries.
Many studies were done on the microleakage of AA and GICs, but this is the pioneer study showing the microleakage of the new innovative dental restorative material that is CN. CN is a tooth-colored, basic filling material for direct restorations. It is self-curing with optional additional light-curing. It is commercially available and consists of a separately packaged powder and liquid that are mixed by hand directly before use. Only disadvantage is that it is available in only one shade.
Minimizing shrinkage stress is particularly important in a full volume replacement material that is applied in bulk. CN, therefore, contains a shrinkage stress reliever with a low modulus of elasticity. It acts like a microscopic spring, attenuating the forces generated during shrinkage. Reduced polymerization shrinkage should translate as lower volumetric shrinkage, improved marginal integrity, and reduced shrinkage stress force over the restorative surface/on the adhesive bond. Therefore, it shows the lowest microleakage among all the other restorative materials.
Limitations of the study
As this is an in vitro study, the clinical performance of any material cannot be predicted solely on the basis of in vitro study. Controlled clinical studies are necessary to draw a definite conclusion of microleakage of different restorative materials. CN is a newer restorative material. Very few articles are available in support of this material. More researches and clinical trials are required in support of this material. Second, the cavities to be prepared for AAs should have retentive walls, differently for cavities that will receive adhesive material. This fact is a bias of the study since the cavity was not properly made for the material to be used.
| Conclusion|| |
Within the limitations of the current study, the following conclusions were drawn:
All the restorative materials used in the study were unable to prevent the microleakage completely. Out of all the restorative materials, CN a newer restorative material displayed minimum microleakage compared to AA and GICs.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Dr. Abiskrita Das
Gurunanak Institute of Dental Sciences and Research Campus, 157/F, Nilgunj Road, Panihati, Kolkata - 700 114, West Bengal
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]