|Year : 2018 | Volume
| Issue : 3 | Page : 201-205
Comparative evaluation of marginal seal integrity of three bulk-fill composite materials in Class II cavities: An In vitro study
Megha C Patel, Rohan K Bhatt, Disha A Makwani, Lipee D Dave, Vijeta S Raj
Department of Pedodontics and Preventive Dentistry, Karnavati School of Dentistry, Gandhinagar, Gujarat, India
|Date of Web Publication||24-Sep-2018|
Disha A Makwani
B-13 Manavmandir Flats, Takshashila Colonials, Ramannagar, Maninagar, Ahmedabad, Gujarat
Source of Support: None, Conflict of Interest: None
Aim: The aim of this study is to compare marginal sealing of three different bulk-fill composite restorations of Class II cavities under in vitro conditions. Materials and Methods: Thirty human extracted pre-molars were divided into three groups of 10 each. Class II cavities were prepared and restored using Filtek Bulk Fill (Group I), Tetric N-Ceram Bulk Fill (Group II) and X-tra Fil Bulk Fill (Group III) composite materials. Depth of dye penetration along the lateral walls of each specimen was evaluated under stereomicroscope, and marginal gap was evaluated under scanning electron microscope. Statistical Analysis Used: In a one-way ANOVA study, statistical analysis will be done using non-parametric, Kruskal–Wallis rank-sum analysis and Chi-square test for categorical data. For all statistical analysis, probability levels of P < 0.05 will be considered statistically significant. Results: Stereomicroscopy showed no dye penetration in 90%, 70% and 30% of restorations in Groups I, II and III, respectively. The mean width of marginal gap (μm) was 1.691, 3.076 and 4.546 in Groups I, II and III, respectively. Conclusions: Under the limitation of in vitro study, Filtek Bulk Fill composite material showed least microleakage and better marginal adaptation.
Keywords: Bulk-fill composite, Class II restorations, marginal microleakage
|How to cite this article:|
Patel MC, Bhatt RK, Makwani DA, Dave LD, Raj VS. Comparative evaluation of marginal seal integrity of three bulk-fill composite materials in Class II cavities: An In vitro study. Adv Hum Biol 2018;8:201-5
|How to cite this URL:|
Patel MC, Bhatt RK, Makwani DA, Dave LD, Raj VS. Comparative evaluation of marginal seal integrity of three bulk-fill composite materials in Class II cavities: An In vitro study. Adv Hum Biol [serial online] 2018 [cited 2020 Jan 24];8:201-5. Available from: http://www.aihbonline.com/text.asp?2018/8/3/201/241923
| Introduction|| |
Restoration of decayed primary teeth requires conservative tooth preparation and materials which are less technique-sensitive, cost-effective and function in mastication for the lifetime of the teeth. Therefore, the focus is on the restorative materials which necessitate less application steps, thus reducing the risk of contamination and the treatment time.
In the past two decades, resin composites have become the first material of choice for almost all kinds of restorations. Volumetric shrinkage occurs in most of the commercially available dental composites which are based on methacrylate chemistry. The drawbacks of the shrinkage mainly include microgap formation at the tooth-restoration interface which causes microleakage, thereby permitting the passage of microorganisms and oral fluids resulting in post-operative sensitivity, pulpal inflammation and secondary caries.
There are various techniques which have been implemented to minimise the polymerisation shrinkage in dental composites. Few of these include the use of resin liner under the restoration, incremental placement of restorative material  and increasing the filler content in the composition. For stress-bearing posterior restorations, packable resin composites were introduced and are characterised by a high filler load along with improved handling property.
The layering technique and thin 2-mm polymerisation increments of the conventional composites are widely recommended for the restorations in the posterior teeth which are a time-consuming activity. When extensive cavities are filled in posterior teeth, such a treatment can imply the risk of incorporating air bubbles or contaminants between the increments.
Bulk-fill type of composite resins has been introduced in the market with a view to simplify the procedure of introducing the material into the cavity and its polymerisation. They may be used either as dentin replacement beneath conventional resin composite or as a single filling material. Bulk-fill composite can be light cured in a single increment up to 4 mm and it makes the work quicker by reducing the number of clinical steps. Thus, it can be used in the paediatric patients as a less time-consuming procedure, thereby increasing the co-operation level of the patient.
The innovative system of polymerisation initiation determines shortening of light-curing time and increasing the depth of cure. Bulk-fill composite resins can be applied in thick layers due to low shrinkage of these materials and high filler content which causes shrinkage stresses to be very low. Due to universal colour of materials, the time of colour-matching process is shorter and shorter time of finishing and polishing of the restoration., Nevertheless, an ideal bulk-fill composite would be one that could be placed into a preparation having a high configuration factor (C-factor) design and still exhibited very little polymerisation shrinkage stress, while maintaining a high degree of cure throughout.
Not all newly introduced restorative materials can have improved physical and mechanical properties and offer ease of use and time-saving characteristics; however, short- and long-term cavity wall adaptability is strongly related with the long-term clinical performance of the material. Thus, the aim of the study was to compare marginal sealing of three different bulk-fill composite restorations of Class II cavities under in vitro conditions.
| Materials and Methods|| |
In total, thirty sound pre-molars, with neither carious lesions nor restorations, recently extracted for orthodontic reasons were selected for this in vitro study. After extraction, the teeth were cleaned from the remaining connective tissue and debris and were rinsed with distilled water and stored at room temperature. The teeth to be prepared were mounted in a plaster block. In each tooth, Class II proximal box cavities of depth of 4 mm (measured along the lateral wall), a width of 2 mm (pulpal wall) and length of 3 mm (approximal wall) [Figure 1] were prepared with a SF-41 diamond bur at high speed with air/water spray. The margins of the cavities were finished with fine diamond bur. All the prepared cavity surfaces were etched with 37% phosphoric acid for 15 s and then rinsed and dried. Fifth-generation bonding agent as dentin/enamel single component adhesive (Stae SDI Limited, Australia) was applied to the etched surface, gently dried and light cured for 20 s in continuous intensity mode at a light intensity 1200 mW/cm2 (LED Light, Unicorn Denmart, New Delhi, India).
|Figure 1: Graphic model of microleakage assessment on the transverse cross section.|
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The teeth then were randomly divided into three groups of 10 each. Group I: Filtek Bulk Fill composite (3M ESPE, USA), Group II: Tetric N-Ceram Bulk Fill composite (Ivoclar Vivadent, Schaan, Liechtenstein) and Group III: X-tra Fil Packable Posterior Bulk Fill composite (Voco, Germany). The specimens in each group were restored with the corresponding bulk-fill composite and light cured according to manufacturer's instructions. The restorations were then finished with TR25EF finishing bur and polished with polishing discs. Restored teeth were stored in distilled water at room temperature for 24 h, and then, they were subjected to 500 thermal cycles at 5°–55° C in a water bath with a dwell time of 15 s between the baths. The samples were then painted with nail varnish leaving 1 mm around the restoration. Prepared samples were placed in 1% methylene blue dye for 24 h. The specimens were then rinsed and sectioned mesiodistally using hard tissue microtome and viewed under stereomicroscope of ×20 magnification for scoring of dye penetration [Figure 2].
The microleakage scoring was done using the method, as per Miroslaw Orlowski.
- 0 – No dye penetration into the filling material or along the filling-tooth interface
- 1 – Dye penetration into the filling material or along the filling-tooth interface up to half of the either lateral wall
- 2 – Dye penetration into the filling material or along the filling-tooth interface along all of the either lateral wall (till bottom of the cavity, pulpal wall)
- 3 – Dye penetration into the filling material or along the filling-tooth interface up to half of both lateral walls
- 4 – Dye penetration into the filling material or along the filling-tooth interface along both lateral walls (till bottom of the cavity, pulpal wall).
Then, the specimens were assessed for microgaps between the restoration and tooth surface using scanning electron microscope (SEM) (×200 magnification) [Figure 3].
| Results|| |
The data analysis was done with IBM SPSS 20 windows statistical software (Chicago, USA). One-way ANOVA and non-parametric, Kruskal–Wallis rank-sum analysis and Chi-square test were used for categorical data. For all statistical analyses, probability levels of P < 0.05 were considered statistically significant.
Dye penetration rating using the grade scale was as follows [Table 1]: the highest rating (score 0, no dye penetration) was achieved by 90% of the restorations made of the Filtek Bulk Fill material, 70% of restorations of Tetric N-Ceram Bulk Fill and 30% of restorations of the X-tra Fil Bulk Fill.
When the three groups were compared for microleakage using Kruskal–Wallis test, there was a significant difference between Group I and Group III and Group II and Group III with P = 0.003 and P = 0.05, respectively [Table 2].
|Table 2: Comparison of significant differences between pairs of composites|
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On analysis by one-way ANOVA, Group I showed a mean width of marginal gaps to be 1.691 μm, which was the lowest among all the groups. Group II showed a mean width of marginal gaps to be 3.076 μm and Group III showed a mean width of marginal gaps of 4.546 μm [Table 3].
When comparison between different pair of groups for gap formation (μm) observed under SEM in different groups was done by post hoc test for multiple comparisons, mean width of marginal gaps of all the three groups was found to differ from each other, and the difference was found to be statistically very highly significant (P < 0.001) [Table 4].
|Table 4: Comparison between different pair of groups for gap formation observed under standard error of mean in different groups|
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| Discussion|| |
Marginal integrity is essential to increase the longevity of any restoration. Polymerisation shrinkage leads to microleakage, thereby compromising this integrity. The magnitude of the stress induced during polymerisation shrinkage depends on various factors, amongst which the C-factor of the cavity and also the effect of light-curing mode is one of those factors. The present study assessed the cavity adaptation of three different bulk-fill composite materials in Class II cavity of pre-molars by assessing the microleakage and microgap formation between the tooth and the bulk-fill material under stereomicroscope and SEM, respectively. In order to eliminate the effect of marginal adaptability as a confounding factor and to evaluate the sealing ability of different materials to the tooth surface, we investigated the sealing ability of the three different materials with the same preparation dimensions, same C-factor, same resin adhesive and light-curing mode for all the restoration specimens. Thermocycling was done to simulate the oral environment.
In paediatric dentistry, it is crucial to select restorative materials with long-term clinical performance and short operating time, especially while working on highly uncooperative paediatric patients. In the current study, when sealing ability of different types of bulk-fill packable composite resins at enamel and dentin margins of Class II cavities was examined, none of the interfaces showed an absence of infiltration, although the degree of infiltration differed in relation to the material. The results of the present study demonstrated significant differences among the systems tested in the cavity adaptation.
Gaintantzopoulou et al. in their study comparing the cavity wall adaptation and gap formation of SonicFill bulk-fill composite resin, EQUIA Fil conventional reinforced glass ionomer cement and Vitremer resin-reinforced glass ionomer cement in Class II restorations on primary molars found that SonicFill bulk fill showed batter cavity wall adaptation than Vitremer resin-reinforced glass ionomer cement.
Bulk-fill composites are more translucent than other restorations so that the light can get too much deeper layers. The content of photoinitiators of polymerisation and stress inhibitors determines the optimal marginal seal of these composites. The relationship between the method of filling cavities and marginal seal of composite fillings was also the subject of Skałecka-Sądel and Grzebieluch research.,
The results of the study showed that there is a significant difference between microleakage of different evaluated bulk-fill composites (P < 0.05). X-tra Fil Bulk Fill composite showed the highest dye penetration under stereomicroscope followed by Tetric N-Ceram and the least by Filtek Bulk Fill. Under scanning electron microscopy, Filtek Bulk Fill showed less marginal gaps (mean width = 1.691 μm) compared to Tetric N-Ceram (mean width = 3.076 μm) and X-tra Fil Bulk Fill (mean width = 4.546 μm).
Rationale for the difference noted in the present study between the different materials tested could be attributed to variance in the properties of the materials tested and their handling characteristics. Filtek Bulk Fill Posterior Restorative contains two novel methacrylate monomers that, in combination, act to lower polymerisation stress. One is a high molecular weight aromatic urethane dimethacrylate which decreases the number of reactive groups in the resin. This helps to moderate the volumetric shrinkage as well as the stiffness of the developing and final polymer matrix, thus reducing the polymerisation stress. The second unique methacrylate represents a class of compounds called addition–fragmentation monomers (AFM). During polymerisation, AFM reacts into the developing polymer as with any methacrylate, including the formation of cross-links between adjacent polymer chains. AFM contains a third reactive site that may cleave through a fragmentation process during polymerisation. This process provides a mechanism for the relaxation of the developing network and subsequent stress relief.
Tetric N-Ceram Bulk Fill is the efficient four millimetres posterior composite of the nano-optimised Tetric N-Collection. The patented light activator Ivocerin is responsible for ensuring the complete four millimetres depth cure of the filling.
No studies have been done comparing the marginal adaptation of Filtek Bulk Fill, Tetric N-Ceram Bulk fill and X-tra Fil Bulk Fill packable composite materials. Hence, the present study evaluated and compared the marginal adaptation of three different packable bulk-fill composite materials, and the results showed that Filtek Bulk Fill composite showed the least microleakage and better marginal adaptation and can be used in paediatric patients with deep Class II cavities where it is difficult to keep isolation, thus completing the restoration quicker than the conventional incremental layering technique.
| Conclusions|| |
Based on the limitations of this in vitro study, it can be concluded that in Class II restorations, microleakage is observed regardless of the bulk-fill composite used, and Filtek Bulk Fill composite shows lesser microleakage and better marginal adaptation as compared to Tetric N-Ceram and X-tra Fil Bulk Fill composites.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]