Research Article COMPARISON BETWEEN LIGHT CURE AND DUAL CURE IN TERMS OF COLOR STABILITY

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1 ISSN: X CODEN: IJPTFI Available Online through Research Article COMPARISON BETWEEN LIGHT CURE AND DUAL CURE IN TERMS OF COLOR STABILITY 1* Sweta.V.R, 2 Dr.Subash Sharma 1 Bachelor of Dental surgery, 2 nd year, Saveetha Dental College and Hospitals, Chennai 2 Senior Lecturer, Department of Conservative Dentistry and Endodontics, Saveetha Dental College and Hospitals, Chennai. swe.ram19@gmail.com Received on: Accepted on: Abstract: Aim: To evaluate if light cure or dual cure is better in terms of color stability. Objective: To compare the color stability of light cure and dual cure resin. Background: Dental composite resins are types of synthetic resins which are used in dentistry for various restorative procedures. Light cure resins are polymers that cure and harden in the presence of specific light spectrums. Dual cure resins use both light and chemical initiators to activate the process of polymerization. In this research, the color stability of dual cure and light cure were studied by placing the resin composites in two media namely, acidic beverage and artificial saliva. The color changes were noted using a spectrophotometer. Based on the result obtained, the color stability was determined. Reason: It is assumed that dual cure has greater color stability as compared to light cure. This study is done to determine if the assumption is valid. Key words: light spectrum, polymerization, spectrophotometer. Introduction The success of any restoration using composite resins depends upon the color stability and degree of polymerization of the resin composite. The polymerization of resin composite depends on many intrinsic conditions, such as the type of the photoinitiator, composition of filler particles, shade and degree of translucency IJPT Dec-2017 Vol. 9 Issue No Page 31005

2 of the materials. In addition, the effective spectral output and irradiance of the light curing unit are needed for adequate polymerization. [1,2] Camphorquinone (CQ) has been used as a photoinitiator ever since the introduction of visible-light activated resin composites. However, alternative photoinitiators have been studied because the intense yellow hue of Camphoroquinone can affect resin esthetics.[3-5] Compounds derived from acylphosphine oxides and phenyl-propanedione (PPD) can also be used as photoinitiators for applications in adhesives and resin composites.the absorption peak of newly developed composite resins (which contain an alternative photoinitiator) are in the near Ultraviolet (UV) region and extends slightly into the visible wavelength (< 420 nm).[3] Nowadays Light emitting diodes (LED) are only used for curing. These LED lights have a peak wavelength in the 470 nm range, which is ideal for curing traditional resin composite using CQ as an activator. Materials and Methods CONTROL(1) ARTIFICIAL SALIVA(2) BEVERAGE(3) LIGHT DUAL LIGHT DUAL LIGHT DUAL CURE CURE CURE CURE CURE CURE (n=3) (n=3) (n=3) (n=3) (n=3) (n=3) In this study in order to compare the color stability of the light and dual cure resin composites of A2 shade, three sets of samples were used. Teflon molds were placed on a glass slab and filled with the resin samples. All the samples were packed into Teflon molds of 8mm diameter and 2mm thickness. After packing the composites, they were light cured with the single peak LED for 30 seconds. They were finished and polished using super pack. The samples were immediately placed in different media namely-control, artificial saliva and beverage. The test samples were named as 1,2 and 3 in both light cure and dual cure. The test samples 1 of both light cure and dual cure were left untouched as control samples. The test samples 2 of both light cure and dual cure were placed in artificial saliva and samples 3 of light cure and dual cure were placed in beverage(miranda). The samples were then left undisturbed for seven days in a dark room. IJPT Dec-2017 Vol. 9 Issue No Page 31006

3 Color difference (ΔE) measurement: Sweta.V.R*et al. /International Journal of Pharmacy & Technology The specimens (n = 18) were placed in their corresponding media for 7 days. The measurements were made according to CIE L*a*b* color scale relative to the CIE standard illuminant D65 over a white background on a reflection spectrophotometer (CM- 3600d, Minolta, Tokyo, Japan) with specular component excluded (SCE) geometry[6]. By applying the formula, ΔE =[(ΔL*) 2 +(Δa*) 2 +(Δb*) 2 ] 1/2, it was possible to calculate ΔE and compare the values after treatment. Result: The values so obtained from testing the samples are given in Table 1. SAMPLE L L 2 A A 2 B B 2 L 2 +A 2 +B 2 (L 2 +A 2 +B 2 ) 1/2 Light cure (1) Dual cure(1) Light cure (2) Dual cure (2) Light cure (3) Dual cure (3) Table 1: Sample 1- control samples Sample 2- artificial saliva Sample 3- beverage (Miranda) Light source: D65 From the above table, we conclude that light cure composite and dual cure composite are similar in terms of color stability. Discussion: Dental resin composites are highly cross linked polymeric materials reinforced by a dispersion of glass, crystalline, or resin filler particles and short fibers bound to the matrix by silane coupling agents. Pigments help to match the color of the tooth structure. Ultraviolet(UV) absorbers and other additives improve color stability and polymerization inhibitors extend storage life and provide increased working time for chemically activated resins. IJPT Dec-2017 Vol. 9 Issue No Page 31007

4 Resin composites are of three types- self cure, light cure, and dual cure. Self cure resins are chemically activated. Light cure resins are photochemically activated. Dual cure resins can be activated either chemically or photochemically.light curable dental composites are supplied as a single paste contained in a lightproof syringe.the free radical initiating system consisting of a photosensitizer and an amine initiator system is contained in this light cure paste. As long as these components are not exposed to sunlight, they do not interact. However exposure to light in the blue region (wavelength of about 468nm) results in an excitatory state of the photosensitizer which in turn reacts with the amine initiator to form free radicals that initiate addition polymerization. The most commonly used photosensitizer is camphoroquinone. A number of amine initiators are suitable for interaction with camphoroquinone like dimethylaminoethylmethacrylate. Dual cure resins are commercially available and consist of two light curable pastes- benzoyl peroxide and aromatic tertiary amine accelerator. They are formulated to accelerate on light curing promoted by CQ-amine combination. To produce a sufficient amount of free radicals for adequate polymerization resin composites must receive sufficient energy in the appropriate wavelength range[7]. The polymerization process may be adversely affected if the LCU does not emit enough light at the wavelengths absorbed by the photoinitiators[8] which may result in reduced hardness[9], decreased biocompatibility[9,10] and decreased color stability[11]. Conclusion: This study revealed that the difference in the color stability between light cure composite and dual cure composite is not significant. Though dual cure composite has many advantages over light cure composite in various properties, in terms of color stability, both the composites are similar. Hence, either light cure or dual cure composite can be used for anterior aesthetic restorations. Acknowledgement: I would like to express my sincere gratitude to Mr.Mohan Kumar, Department of plastic technology, CIPET, Chennai for providing us the spectrophotometer for this research project. References: 1. Fan PL, Schumacher RM, Azzolin K, Geary R, Eichmiller FC. Curing-light intensity and depth of cure of resin-based composites tested according to international standards. J Am Dent Assoc 2002;133: IJPT Dec-2017 Vol. 9 Issue No Page 31008

5 2. Yap AU, Soh MS, Han TT, Siow KS. Influence of curing lights and modes on cross-link density of dental composites. Oper Dent 2004;29: Park YJ, Chae KH, Rawls HR. Development of a new photoinitiation system for dental light-cure composite resins. Dent Mater 1999;15: Tak HS, Park SJ. Influences of camphoroquinone on the properties of composites. J Kor Acad Cons Dent 2001;26: Neumann MG, Schmitt CC, Ferreira GC, Corre a IC. The initiating radical yields and the efficiency of polymerization for various dental photoinitiators excited by different light curing units. Dent Mater 2006;22: Hye-Jung Park, Sung-Ae Son, Bock Hur, Hyeon-Cheol Kim, Yong-Hoon Kwon, Jeong-Kil Park;Effect of the difference in spectral outputs of the single and dual-peak LEDs on the microhardness and the color stability of resin composites;doi: / JKACD Nomoto R, effect of light wavelength on polymerization of light cured resins. Dent Mater 1997;16: Schneider LF,, Pfeifer CS, Consani S, Prahl S, Ferracane JL. Influence of photoinitiator type on the rate of polymerization, degree of conversion, hardness and yellowing of dental resin composites. Dent Mater 2008:24: De souza costa CA, Hebling J, Hanks CT. effects of light curing time on the cytotoxicity of a restorative resin composite applied to an immortalized odontoblast cell line. Oper Dent 2..3;28: Roh BD, Park SH, Lee CS. An experimental study on degree of conversion and cytotoxicity of dual cure resin cements. J Kor Acad Cons Dent 1995;23: Imazato S, Tarumi H, Kobayashi K, Hiraguri H, Oda K, Tsuchitani Y. relation between the degree of conversion and internal discolouration of light activated composites. Dent matr 1995;14: Corresponding Author: Sweta.V.R*, swe.ram19@gmail.com IJPT Dec-2017 Vol. 9 Issue No Page 31009