|Year : 2017 | Volume
| Issue : 1 | Page : 12-15
In vitro analysis and comparison on depth of cure in newer bulk fill composite resin with conventional micro- and nano-hybrid composite resin using two different light sources quartz-tungsten-halogen and light emitting diode with three varying intensities
Kamatchi Subramani Savadamoorthi1, Swathi Priyadharshini1, Anand Sherwood1, Kandasamy Paulraj Jesudoss2, Vasanthan Vignesh Kumar3, Ananthi Christopher4
1 Department of Conservative Dentistry and Endodontics, C.S.I. College of Dental Sciences and Research, Madurai, Tamil Nadu, India
2 Department of Prosthodontics, C.S.I. College of Dental Sciences and Research, Madurai, Tamil Nadu, India
3 Department of Orthodontics, C.S.I. College of Dental Sciences and Research, Madurai, Tamil Nadu, India
4 Department of Pedodontics, C.S.I. College of Dental Sciences and Research, Madurai, Tamil Nadu, India
|Date of Web Publication||28-Feb-2017|
Kamatchi Subramani Savadamoorthi
Department of Conservative Dentistry and Endodontics, C.S.I. College of Dental Sciences and Research, East Veli Street, Madurai - 625 001, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Aims: The current in vitro analysis evaluated the depth of cure in newer bulk fill composite resin which compared the traditionally used hybrid and microfill composite resin which used two different light sources quartz-tungsten-halogen (QTH) and light emitting diode (LED) unit with three varying intensities in conventional standard curing mode for 20 s. Materials and Methods: Three composite resins were selected for this study, namely, bulk fill (Smart Dentin Replacement, Dentsply), hybrid (Tetric N – Ceram, Ivoclar), and microfill (Te-Econom Plus, Ivoclar) with four different thickness 2, 4, 6, and 10 cured with varying intensities (625, 850, and 1025 mW/cm2) using two different light sources QTH (QHL 75, Dentsply) and LED (Ledition, Ivoclar and Valo, Ultradent). The depth of cure was determined using a scraping method based on ISO 4049:2000. Statistical Analysis Used: Data were analyzed using Kolmogorov–Smirnov test, Kruskal–Wallis test is applied followed by Bonferroni-corrected Mann–Whitney test. Results: Best depth of cure results were obtained with a bulk fill composite resin cured under 1025 mW/cm2 intensity using LED. Bulk fill showed the highest curing depth results in all varied intensities. Conclusions: Bulk fill composite resin was found to be more successful than hybrid and microfill composite resin with respect to the depth of cure.
Keywords: Bulk fill composite resin, curing mode, depth of cure, light intensity
|How to cite this article:|
Savadamoorthi KS, Priyadharshini S, Sherwood A, Jesudoss KP, Kumar VV, Christopher A. In vitro analysis and comparison on depth of cure in newer bulk fill composite resin with conventional micro- and nano-hybrid composite resin using two different light sources quartz-tungsten-halogen and light emitting diode with three varying intensities. J Int Oral Health 2017;9:12-5
|How to cite this URL:|
Savadamoorthi KS, Priyadharshini S, Sherwood A, Jesudoss KP, Kumar VV, Christopher A. In vitro analysis and comparison on depth of cure in newer bulk fill composite resin with conventional micro- and nano-hybrid composite resin using two different light sources quartz-tungsten-halogen and light emitting diode with three varying intensities. J Int Oral Health [serial online] 2017 [cited 2019 Nov 14];9:12-5. Available from: http://www.jioh.org/text.asp?2017/9/1/12/201090
| Introduction|| |
Bulk fill technique has been widely used due to the development of material with improved depth of curing., Increments for cavity filling are reduced when compared with conventional composite resin. In contrast to 2 mm increment for conventional composite resin, bulk fill composite resin recommends 4–5 mm increment, so it simplifies the restorative procedure by saving operator time. Thicker increment is achieved due to the development in photoinitiator dynamics with increased translucency, which helps additional light to penetrate for a deep curing., Newer bulk fill material justifies further investigation due to the properties of composite resin which depend on its composition.
A new type of flowable composite resin with the advantage was introduced (Surefil Smart Dentin Replacement [SDR] Dentsply, Caulk, USA) as bulk fill material. The new material is placed as a bulk without negatively affecting polymerization shrinkage, degree of conversion. Moreover, manufacturer states that polymerization shrinkage of this material is even lower when it is compared with commonly used conventional composite resin. Drawbacks related to polymerization shrinkage like gap formation which causes secondary carious lesion due to colonization of bacteria. Postoperative sensitivity, pulp irritation when chewing or cusp deflection with high “c” factor could be minimized. Manufacturers claim that SDR bulk fill material can achieve a depth of cure 6 mm, though no published investigation is available till now to confirm this. Placing a self-adapting material as bulk saves more time and improves the handling.
Resin back bone of Surefil SDR has a polymerization modulator to reduce polymerization shrinkage. This modulator molecule has the ability to optimize flexibility because of conformational flexibility around the modulator. Studies on SDR composites have shown significantly reduced shrinkage stress values compared to nanohybrid and silorane-based composites. Moreover, SDR when used for luting fiber posts resulted in comparable retentive strength like dual cure resin commonly used. But till date, no study has been done to evaluate the depth of cure of flowable bulk fill composites with different intensities of light cue unit so the aim of our present study is to compare the depth of cure of low viscosity bulk fill composite resin (SDR, Dentsply, Caulk, Milford, DE, USA) with a conventional composite resin (Tetric N Ceram, Ivoclar Vivadent; QHL 75, Dentsply) using different intensities of light cure units.
| Materials and Methods|| |
The investigated materials were extruded from their respective capsules with the help of a manual applicator. Two varying light sources were used with varying intensities (VALO, Ultradent; Ledition, IvoclarVivadent; and QHL75, Dentsply).
The depth of cure of the investigated materials [Table 1] was assessed as per the International Organization of Standards 4049. Each material was inserted in a metallic mold with an orifice 4 mm in diameter and 2, 4, 6, and 10 mm in depth. The model was lined inside with polyester and covered by Mylar strips, placed on white filter paper, and light activated with three varying intensities (1025 mW/cm2 Valo, Ultradent; 850 mW/cm2 Ledition, Ivoclar Vivadent; and 625 mW/cm2 QHL 75, Dentsply) from the upper orifice for 20 s in conventional mode. Each specimen was removed from the mold, and the uncured material in the bottom was scraped off with a spoon excavator. The height of the hardened material was measured in the center of the specimen with micrometer. Triplicates were conducted for each investigated material.
|Table 1: Investigated restorative materials and their composition according to information provided by the respective manufacturers|
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Data were analyzed using Statistical Package for Social Sciences (SPSS 20.0, IBM Corp., U.S.A). Normality test Kolmogorov–Smirnov test results show that depth of the curve does not follow normal distribution, therefore, nonparametric tests were applied. To compare the materials and intensities, Kruskal–Wallis test was applied followed by Bonferroni-corrected Mann–Whitney test. Each group being was compared against the control group. The depth of cure was, in general, improved for the bulk fill composite resin when compared with the conventional composite resin, when the intensity of the light source is increased, the depth of cure increased in bulk fill composite resin and conventional composite resins.
| Results|| |
The mean value and standard deviation of the depth of cure between materials and intensities are summarized in [Table 2] and [Table 3]. There was a significant difference found with the scrapping test between the materials and between intensities (P > 0.05). Even though all the investigated composite resins showed increased curing depth when the intensity was increased, SDR composite resin showed increased curing depth compared to microfill and hybrid resin composite for all varied intensities. However, best depth of cure result was achieved when SDR resin composite was cured at 1025 mW/cm2. SDR bulk fill composite resin had the best depth of cure at all different thickness when compared to other types of conventional composite resins.
|Table 2: Kruskal-Wallis test to compare the depth of the cure between the materials and Mann-Whitney test with Bonferroni correction for pair-wise comparison of intensities|
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|Table 3: Kruskal-Wallis test to compare the depth of the cure between the intensities and Mann-Whitney test with Bonferroni correction for pair-wise comparison of intensities|
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| Discussion|| |
Composites resins are used widely in restorative dentistry. Composite resins with improved mechanical properties have been developed over the years due to high esthetic demand. The effectiveness of cure depend on the intensity of the light source, type of fillers used size, and quantity., Cure of light-activated composites is important to prevent cytotoxicity. The depth of cure throughout the bulk of visible light-activated composite resin is important to the clinical success of the restoration.
Bulk fill composite resin is in routine restorative practice, but concerns about the polymerization shrinkage, stress caused reluctance in its use. To overcome this negative effect, low-shrinkage resin composite has been developed with success by modifying the monomer technology.,, The demand for bulk fill has more recently been approached due to the introduction of flowable composite that can be cured in one layer up to a thickness of 4 mm.,, Although flowable composite shrinks more than conventional composite resin stress relieving flowability, potentially enhanced by “polymerization modulator” as claimed by manufacturers which can be chemically embedded in the polymerizable resin backbone of SDR.,
SDR composites have other dimethacrylates as organic matrix instead of bis-phenol-A-dimethacrylates. Because of this SDR, composites are less viscous.
The other dimethacrylates such as urethane dimethacrylate and ethoxylated bisphenol A dimethacrylate (EBPDMA) are more flexible than bisphenol A glycidyl methacrylate (BIS-GMA) polymer. In addition, BIS-GMA has the disadvantage of being more hydrophilic than EBPDMA because of this, BIS-GMA-based composites have the risk of water absorption and degradation. Therefore, the EBPDMA-based composites, which is more hydrophobic, have less chance of discoloration. The depth of cure in composites can be kept higher by increasing the concentration of monomers or diluents in the material, which will not improve the mechanical properties of the material. However, in studies comparing the mechanical properties of SDR composites with other composite resins, SDR showed better and improved values than other composites. This shows that in SDR composites, monomer or diluents concentration has not been altered.
Analysis of spectral emission shows that light emitting diodes (LEDs) have a homogeneous emission concentrated in a narrow band very close to the peak of absorption of camphorquinone that is 470 nm. Only wavelength which is immediately absorbed by photoinitiator contributes photoactivation. All the light emitted by LED is within the spectrum of maximum absorption of camphorquinone, whereas quartz-tungsten-halogen (QTH) lamps produce light outside the spectrum of interest, furthermore the use of filters is necessary to restrict the wavelengths and system of ventilation is needed to eliminate heat produced by QTH, this component degrades over time, which in turn reduces the efficiency of the unit.
| Conclusion|| |
Bulk fill composite resin was found to be more successful than Hybrid & Micro fill composite resin with respect to depth of cure. Increasing the intensity enhances the depth of cure in all composite resins, with the bulk-fill composite resin showing the highest depth of cure for all three intensities, even for increased thickness of the material. Best depth of cure was achieved for bulk-fill composite resins when it was cured at 1025 mW/cm2.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]