Microleakage assessment using 7th generation bonding agent with
micro-hybrid composite restoration immersed in a carbonated drink – an in vitro study
Amith A Singh1, Ravi Gupta2, Swetha3, Bharath Rao4,
1Reader, Department of Prosthodontics and Crown and Bridge,
Manipal College of Dental Sciences, Manipal Academy of Higher Education, Manipal.
2Senior Lecturer, Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences, Mangalore, Manipal Academy of Higher Education, Manipal, India
3Post Graduate, Department of Public Health, Prasanna School of Dental Health,
Manipal Academy of Higher Education, Manipal.
4Department of Oral Biology, Melaka Manipal Medical College,
Manipal Academy of Higher Education, Manipal.
*Corresponding Author E-mail: ravi.gupta@manipal.edu
ABSTRACT:
Introduction: Restored teeth in the course of chewing or when exposed to thermal stimuli may lead to sensitivity. One of the significant reasons for sensitivity is microleakage. The repercussion of unaddressed microleakage leading to secondary caries and further on. The purpose of this study was to compare the microleakage of amongst different types of restorative materials which were silver amalgam and micro-hybrid composite resin with 7th generation bonding agent. And also to examine the effect of carbonated drink on microleakage. Materials and method: Forty extracted premolars were used for the study. Class V cavities were prepared on the buccal surfaces of the teeth, 1mm above the cementoenamel junction cervico-occlusal. Twenty cavities were restored with silver amalgam, and the remaining with composite resin. Group I and Group II both comprised of 10 teeth with silver amalgam restoration and ten teeth with composite resin restoration were immersed in the carbonated drink and water respectively for 15 minutes for ten days. The teeth were later immersed in methylene blue, sectioned and evaluated under a microscope. Statistical analyses used were Fisher's exact test. Result: Silver amalgam showed highest microleakage tendency in the carbonated drink, (P > 0.05). In water, silver amalgam had the least tendency for microleakage. However, composite resin did not statistically significant microleakage in both carbonated drink and water. Conclusion: The silver amalgam restorations showed microleakage in both carbonated drink and water. The microleakage was significantly higher in the carbonated beverage. On the other hand, composite resin restoration showed microleakage neither in carbonated drink nor water.
KEYWORDS: Methylene Blue, Coke, Water, Composite Resins, Carbonated Beverages.
INTRODUCTION:
In a generation where improvisation and perfectionism are intended, with aesthetics as an essential aspect, we need to know the best possible options to a successful dental restoration. Restorative dentistry has evolved to have tooth coloured restorative material like composite resin which is supplementary to dental amalgam. Composite resin has become a popular alternative to dental amalgam due to its aesthetic advantages. However, dental amalgam which has been successfully used as a restorative material for more than 170 years remains the predominant direct material for load-bearing restorations in the posterior teeth. 1
However, microleakage was identified as a significant problem with amalgam because of interfacial gap formation. 1Although corrosion products from amalgam alloys may eventually seal the interfacial gap between the tooth surface and the amalgam restoration, numerous investigations regarding microleakage around amalgam restorations have been published over the years. 1 The composite resins, on the other hand, have the main advantage of aesthetics as well as decreased chances of microleakage. The microleakage was reduced due to the micromechanical bonding. These were achieved by the hybrid layer and resin tags formation.
Microleakage may be defined as the clinically undetectable passage of bacteria, fluids, molecules or ions between a cavity wall and the restorative material. 1
Recent studies showed that increased consumption of carbonated drinks could be one of the reasons to cause microleakage2. It can be presumed that restorations are subjected to low pH in the oral cavity leading to a degradation of surface integrity. 3The presence of a gap can also cause sensitivity when chewing or exposure to thermal stimuli and even lead to secondary caries. 4 Though the threshold for the individual may vary, the after-effects would be the same. Every plaque retention site is always a possible site for secondary caries to occur. Oral bacteria can multiply in the crevice around the restoration in a short period from the oral environment, tooth surface or smear layer. Subsequently, the bacteria and their toxic products diffuse through dentinal tubules and cause pulpal inflammation.
There is limited literature reporting the effects of beverages on the marginal integrity of these restorative materials5. The present study was designed and carried out to evaluate the microleakage and compare the silver amalgam restoration and micro-hybrid composite resin with 7th generation bonding agent restoration immersed in carbonated drink and drinking water.
MATERIALS AND METHODS:
A total of 40 extracted human premolars were collected and stored in normal saline solution. The teeth were non-carious, intact, had no developmental defects, no fracture and unrestored. These teeth were mounted in a custom made modelling wax (DPI, Rudrapur, Uttarakhand, India) blocks for easy of handling shown in figure 1.
Figure 1: Teeth mounted on a custom made wax block.
Standardised class V cavities were prepared on the buccal surfaces of the teeth (Figure 2: Class V cavity prepared). The shape of the cavities' was trapezoidal with 2mm depth, 1mm above the cementoenamel junction (CEJ) cervico-occlusal. The dimensions of the trapezoid were 1mm in width, 3mm and 4mm for the bases. Retentive grooves were made on the axial wall line angles for retention of silver amalgam restorations.
Figure 2: Class V cavity prepared
Dental varnish (Namuvar, Deepti Dental Products of India Pvt.Ltd., Ratnagiri, India) was applied to 20 cavity preparations to prevent microleakage using applicator tips. The teeth were restored with silver amalgam restoration. An Amalgamator was used to mix non-gamma-2 lathe cut amalgam alloy (DPI, Rudrapur, Uttarakhand, India) and mercury (VIP, Venson's India, Bengaluru, India) together.
To the other 20 teeth, 7th generation single step bonding agent (G-BOND®, GC Corporation, Tokyo, Japan) was applied into the prepared cavities using applicator tips and light-cured for 15 seconds (3MTM ParadigmTM curing light, 3M, Minnesota, USA). The teeth were then restored using light cure composite-radiopaque (RestoFill, Anabond Stedman pharma research Pvt Ltd, Chennai, India) and light-cured for 20 seconds using the layering technique.
The samples were then immersed in the carbonated drink (Coca cola®, Hindustan Coca - Cola Beverages Pvt. Ltd, Bengaluru, India) and distilled water. Ten teeth with silver amalgam and ten teeth with composite resin restoration were immersed in distilled water. The other ten teeth with silver amalgam and ten teeth with composite resin restoration were immersed in the carbonated drink. The teeth were sunk into the solutions for 15 minutes daily over a period of ten days and then transferred into saline solution with a pH of 7.2-7.4. After ten days, all the teeth were immersed in 10% methylene blue solution for 24 hours. The samples were then rinsed with saline solution and stored in saline solution for another 24 hours.
The teeth were then sectioned longitudinally in the middle of the restoration and thinned, using carborundum disc, diamond disc and combination stone. The ground section of the teeth was then observed under a compound microscope at 40x magnification (Nikon Eclipse E200, Nikon Corporation, Tokyo, Japan) and Nikon microscope imaging software to evaluate the degree of microleakage (figure 3: the magnified image of the ground section). The dye penetration was graded based on the extent of infiltration along the occlusal wall of the restoration using the criteria recommended by Michal Staininec and Mark Holtz (1988). A total of 3 people observed the degree of microleakage of solutions and an average of the scores were recorded. (Figure 4: with the score - 3, in the composite restoration sample)
Figure 3: the magnified image of the ground section
Figure 4: with a score - 3, in the composite restoration sample
Results:
The data was analysed using (SPSS version16). Fisher's exact value test was used to analyse the data and assess the significance
Table 1: Microleakage scores for Silver Amalgam immersed in carbonated beverage and water
|
|
Score 0 |
Score 1 |
Score 2 |
Score 3 |
Fisher's Exact Value |
Exact Sig (2-sided) |
|
|
Groups |
Coke |
1 |
0 |
3 |
10 |
19.903 |
P < 0.001* |
|
Water |
11 |
0 |
3 |
0 |
Level of significance at P<0.05; *significant (p<0.001) [Chi-Square/Fisher’s test]
Table 2: Microleakage scores for Composites immersed in carbonated beverage and water
|
|
Score 0 |
Score 1 |
Score 2 |
Score 3 |
Fisher's Exact Value |
Exact Sig (2-sided) |
|
|
Groups |
Coke |
0 |
2 |
4 |
8 |
11.104 |
P < 0.01* |
|
Water |
7 |
2 |
3 |
2 |
Level of Significance at P < 0.05; *Significant (P<0.01)/ [Chi-Square/Fisher’s test]
Table 3: Micro-leakage scores for silver amalgam and Composites
|
|
Score 0 |
Score 1 |
Score 2 |
Score 3 |
Fishers Value |
Exact Sig. (2-sided) |
|
|
Coke |
Silver Amalgam |
1 |
0 |
3 |
10 |
2.97 |
0.501 |
|
Composites |
0 |
2 |
4 |
8 |
|
NS |
|
|
Water |
Silver Amalgam |
11 |
0 |
3 |
0 |
4.196 |
0.172 |
|
Composites |
7 |
2 |
3 |
2 |
|
NS |
Level of significance P<0.05; NS – Not significant
Silver Amalgam restoration [P < 0.001; Fishers Exact test] and Composite restoration [P < 0.01; Fishers Exact test] when immersed in carbonated drink scored significantly higher for microleakage than when immersed in water. Therefore according to the protocol, silver amalgam and composite restorations when exposed to carbonated drink for 15 minutes/day for ten days, resulted in significant microleakage. (Table 1, 2)
Silver amalgam showed highest microleakage tendency in group I (carbonated drink) which was not statistically significant. (P > 0.05). In group II, silver amalgam restoration had the least tendency for microleakage, which was also not statistically significant. (Table 3)
DISCUSSION:
Microleakage is defined as the clinically undetectable passage of bacteria, fluids, molecules, or ions between a cavity wall and the restorative material applied to it. Microleakage at the tooth or restoration interface is considered to be a significant factor influencing the longevity of the dental restoration. It may lead to staining at the margins of the restorations, a hastening of the breakdown of the marginal areas of the restoration, recurrent caries at tooth or restoration interface, hypersensitivity of restored tooth and development of pulpal pathology.
Phosphoric acid is a common constituent of most of the soft drinks. The acid content of the carbonated beverage, which is added to give a peculiar tangy taste and has a preservative property is known to play a well-established role in microleakage.
Restoring a non-carious lesion presents a unique clinical challenge, as that requires material which can adhere to two different types of tooth tissue, i.e. both enamel and dentin. Silver amalgam restoration stays on the cavity by mechanical retention and composite bonds equally well to enamel and dentin, therefore are the materials of choice on restoring cervical lesions.
The class V cavities were prepared 1mm above the CEJ as it's observed that there will be minimal microleakage above the CEJ. The adhesives seal enamel and dentin margins better than cementum.
To evaluate the microleakage using different restorative materials will be justified if the cavity preparations are similar. 40 Standardised Class V cavities were prepared. Though the mineral content may differ in each sample, 2 the technique was the same for all the restorations. A similar study by Farhin Katge et al. had prepared eighty non-carious maxillary premolars. The cavities were restored with nanocomposite on the buccal surface and nano-ionomer on the palatal surface and thermocycled. The experimental groups were randomly divided into three groups of 24 teeth and immersed in fruit drink, fresh fruit juice and soft drink respectively. The teeth were finally soaked in Rhodamine B dye, sectioned and evaluated under a stereomicroscope. 6
Da Silva MA et al. conducted a study on sixty bovine incisors were prepared and restored using nanoparticulate resin. A (control)-Immersion in artificial saliva, immersion in coffee and immersion in (Coke) carbonated drink. Then the samples were analysed for microleakage (dye penetration) and surface roughness (atomic force microscope). 7
The consumption of carbonated drink in a day will not sum up to 24hours. An average time, the teeth exposed to carbonated drink was considered as 15 minutes. 2,3,8 The teeth were immersed in the solutions for 15 minutes daily over ten days and then transferred into saline solution with a pH of 7.2-7.4. In a study by Prasad Chitra and Rohan Pulgaonkar, forty-eight extracted human premolars were bonded with Orthodontic brackets using composite resin. The teeth were dipped in the drinks three times daily for 15 minutes at equal intervals for 15 days and then tested for bond strength, ARI and microleakage values using the universal Testing machine and methylene blue staining respectively.5
After the10 days, all the teeth were immersed in 10% methylene blue solution for 24 hours. The samples were then rinsed with saline solution and stored in saline solution for another 24 hours. T Alptekin et al. in a similar study had the specimens immersed in basic fuchsin for 24 hours and sectioned. Microleakage was examined. 1 Mayank U et al. also stored all the sample in distilled water post-exposure to the die. 9
Microleakage was evaluated using a 0-4 scale for dye penetration. 10 It is a widely accepted method to access microleakage. 11,12 The studies by Kosmas Tolidis et al. and H. Afshar et al. on microleakage, had a similar methodology to assess dye penetration. 13,14
The sectioned samples were assessed. Foo Chay Siang et al. in a study, the teeth were longitudinally sectioned at the middle of a restoration, and the leakage was evaluated under a stereomicroscope. 15,16
The microleakage of composite resin restoration, when immersed in the carbonated drink, has a significant difference compared to when it is immersed in drinking water. There is more microleakage in composite resin restoration when it is immersed in the carbonated drink. Could the use of 7th generation bonding agent be the reason? Is complete removal of the smear layer questionable? Leading failure of the restoration? It could also be because of the acidic content in the carbonated drink eroding the composite resin restoration. 17,18
Silver amalgam restoration had more microleakage than composite resin restoration in the samples immersed in the carbonated drink. The acidic pH might be a contributing factor. Silver amalgam had less microleakage than composite resin restoration in samples immersed in drinking water. The self-sealing property can be an attribute to decreasing the microleakage. The time constraining us, the self-sealing property cannot be well justified in this study. 19,20
ACKNOWLEDGEMENTS:
I would like to thank II BDS students of MMMC, Manipal, MAHE, Ms Hemaareekaa K Mukaya, Ms Lee Jing Wie, Mr Lau E Ren, Ms Mabel Manggang Unchat, Ms Lai Jye Yu, Ms Michelle Cheah Joe Qian and Ms Tan Huey Fang for the effort render for data collection of the study.
CONCLUSION:
Within the limitation of the study, silver amalgam restoration showed higher microleakage tendency in carbonated drink compared to composite restoration. Low pH could be contributing to the failure of silver amalgam restoration. In contrast, silver amalgam has the least tendency for microleakage in water. Silver amalgam has a self-sealing property which explains the fact that it exhibits less microleakage compared to composite. This can be one of the reasons for considering the silver amalgam restoration as a gold standard.
There is no ideal restorative material for a precise condition. The discretion is on to the operator to choose an appropriate restorative material and technique for the excellent prognosis.
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Received on 11.08.2020 Modified on 18.12.2020
Accepted on 09.02.2021 © RJPT All right reserved
Research J. Pharm.and Tech 2022; 15(2):842-846.
DOI: 10.52711/0974-360X.2022.00140