MICROSCOPY RESEARCH AND TECHNIQUE 00:00–00 (2014)
Influence of Light Curing Units and Fluoride Mouthrinse on Morphological Surface and Color Stability of A Nanofilled Composite Resin ANA LUISA BOTTA MARTINS DE OLIVEIRA,1* ANA CAROLINA BOTTA,2 JULIANA ALVARES DUARTE BONINI CAMPOS,1 AND PATRICIA PETROMILLI NORDI SASSO GARCIA1 1 2
Department of Social Dentistry, Araraquara School of Dentistry, University of S~ ao Paulo State, S~ ao Paulo, Brazil Department of General Dentistry, Stony Brook School of Dental Medicine, New York
KEY WORDS
fluorine; composite resins; color; dental technology; SEM
ABSTRACT Composite resin is a dental material susceptible to color change over time which limits the longevity of restorations made with this material. The influence of light curing units and different fluoride mouthrinses on superficial morphology and color stability of a nanofilled composite resin was evaluated. Specimens (N 5 150) were prepared and polished. The experimental groups were divided according to the type of light source (halogen and LED) and immersion media (artificial saliva, 0.05% sodium fluoride solution-manipulated, Fluordent Reach, Oral B, Fluorgard). Specimens remained in artificial saliva for 24-h baseline. For 60 days, they were immersed in solutions for 1 min. Color readout was taken at baseline and after 60 days of immersion. Surface morphology was analyzed by Scanning Electron Microscopy (SEM) after 60 days of immersion. Color change data were submitted to two-way Analysis of Variance and Tukey tests (a 5 0.05). Surface morphology was qualitatively analyzed. The factor light source presented no significant variability (P 5 0.281), the immersion media, significant variability (P < 0.001) and interaction between factors, no significant variability (P 5 0.050). According to SEM observations, no difference was noted in the surface of the specimens polymerized by different light sources, irrespective of the immersion medium. It was concluded that the light source did not influence the color stability of composite, irrespective of the immersion media, and among the fluoride solutions analyzed, Fluorgard was the one that promoted the greatest color change, however, this was not clinically perceptible. The immersion media did not influence the morphology of the studied resin. Microsc. Res. Tech. 00:000–000, 2014. V 2014 Wiley Periodicals, Inc. C
INTRODUCTION The composite resin is a direct restorative material and it is considered the material of choice whenever esthetic appearance is a concern. However, the composite resin presents some deficiencies that may affect its color stability, compromising the quality and longevity of restorations (De Oliveira et al., 2014). The etiology of color change of composites is multifactorial (Hosoya, 1999; Janda et al., 2005; Kolbeck et al., 2006; Mutlu-Sagesen et al., 2005; Nasim et al., 2010; Patel et al., 2004; Pires-de-Souza et al., 2007; Villalta et al., 2006), and may involve intrinsic (Eldiwany et al., 1995; Hosoya, 1999; Iazzeti et al., 2000; MutluSagesen et al., 2005) and extrinsic factors (Bagheri et al., 2005; Fontes et al., 2009; Iazzeti et al., 2000). The intrinsic factors involved in color stability of resin composites are related to the characteristics of the restorative material. The type of organic matrix, inorganic load particle size and its percentage of the composition are factors that may interfere in the optical properties of composite resin (Bagheri et al., 2005; Hosoya, 1999; Mundim et al., 2010; Mutlu-Sagesen et al., 2005; Patel et al., 2004; Voltarelli et al., 2009). Also as intrinsic factor there is the degree of polymer conversion that according to Patel et al. (2004) and C V
2014 WILEY PERIODICALS, INC.
Usumez et al. (2005), it may also influence the susceptibility to staining of the resin. Therefore, the type of light curing source and power density of the light activation unit play an important role in composite resin color stability (Mutlu-Sagesen et al., 2005; Santos et al., 2010; Usumez et al., 2005). There are various types of light curing sources, with the halogen and light emitting diode—LED type being those most frequently used (Aravamudhan et al., 2006; Cekic-Nagas et al., 2010; Martinelli et al., 2006; Piresde-Souza et al., 2007). Although halogen light appliances are low cost, it emits light within the blue spectrum and the process to obtain it results in an excessive loss of energy in the form of heat, resulting in degradation of the light bulb, reflector and filter over the time (Brandt et al. 2010; Martinelli et al., 2006; Pires-deSouza et al., 2007; Usumez et al., 2005; Voltarelli et al., 2009). The LED units use semiconductors to produce *Correspondence to: Ana Luısa Botta Martins de Oliveira, Orlando Damiano, 2281 S~ ao Carlos, S~ ao Paulo, CEP: 13560-450, Brazil. E-mail: [email protected] Received 1 April 2014; accepted in revised form 31 July 2014 REVIEW EDITOR: Prof. Alberto Diaspro DOI 10.1002/jemt.22421 Published online 00 Month 2014 in Wiley Online Library (wileyonlinelibrary.com).
2 Immersion media
A.L.B. MARTINS DE OLIVEIRA ET AL. TABLE 1. Identification and characteristics of immersion media used in study Manufacturer Flavor Color Composition
Artificial saliva
Santa Paula Pharmacy, Araraquara, SP, Brazil
Flavorless
Colorless
Sodium fluoridemanipulated Fluordent Reach
Santa Paula Pharmacy, Araraquara, SP, Brazil Johnson & Johnson, S~ ao Jos e dos Campos, SP, Brazil
Flavorless
Colorless
Mint
Green
Oral B
Gillette, S~ ao Paulo, SP, Brazil
Mint
Blue
Fluorgard
Colgate, S~ ao Bernardo do Campo, SP, Brasil
Cherry
Red
the blue light, which consume little energy during their light emission process (Martinelli et al., 2006; Pires-de-Souza et al., 2007; Usumez et al., 2005; Voltarelli et al., 2009). Among the extrinsic factors, factors related to the dentist such as finishing and polishing procedures and those related to patient behavior, such as poor oral hygiene and diet based on foods and beverages containing pigments are highlighted (Badra et al., 2005; De Oliveira et al., 2014; Domingos et al., 2011; Mundim et al., 2010; Oliveira et al., 2010, 2014; Patel et al., 2004; Santos et al., 2010). In this context, the use of fluoridated mouthrinses on a daily basis, when routinely used may change the color and surface morphology of composite resins due to their chemical composition (Garcia et al., 2002). The staining susceptibility of microfilled and hybrid composites has been extensively studied in the last years. Moreover, the properties of nanofilled resins need to be investigated further, since they has a higher percentage of load and nanoclusters, capable of improving properties (Mitra et al., 2003; Yap et al., 2004) such as color stability. Although studies assessing staining susceptibility of nanofilled resins in various immersion media have been performed, (De Oliveira et al., 2014; Domingos et al., 2011; Fontes et al., 2009; Oliveira et al., 2012, 2014; Santos et al., 2010) the influence of fluoride mouth rinse solutions on the color stability of nanofilled resins cured by different light sources is unknown. The aim of the present study was to investigate the influence of light curing sources on the color stability
Potassium chloride (0.96 g), sodium chloride (0.67 g), magnesium chloride (0.04 g), potassium phosphate (0.27 g), calcium chloride (0.12 g), nipagin (0.01 g), nipasol (0.1 g), carboxymethyl cellulose (8.0 g), sorbitol (24.0 g) and water (1000 ml). 0.05% Sodium fluoride 0.05% Sodium fluoride, water, glycerin, ethyl alcohol, Poloxamer 407, methylparaben, mint aroma, dibasic sodium phosphate, sucralose, monobasic sodium phosphate, cetylpyridinium chloride, propylparaben, yellow food coloring 5, FD&C food coloring No. 1. 0.05% Sodium fluoride, water, glycerin, PEG-40 hydrogenated castor oil, methylparaben, 0.053% monohydrated cetylpyridinium chloride, sodium saccharin, sodium benzoate, propylparaben, FD&C blue No. 1. 0.05% Sodium fluoride, water, sorbitol, polysorbate 20, potassium sorbate, sodium biphosphate, phosphoric acid, red coloring, aromatic composition.
pH 7.00
5.36 6.96
5.41
4.13
and surface morphology of a nanofilled composite resin, considering the use of fluoridated solutions. MATERIALS AND METHODS This research is a double-blind experimental in vitro study. The dependent variable was the color stability and the independent variables were light curing units (XL 3000/3M-ESPE—480 mW/cm2 and Ultralume LED 5/Ultradent—790 mW/cm2) and immersion media (Table 1). The association between curing light units and immersion media resulted in 10 groups. The number of samples used for each experimental condition was established at 15 (N 5 150). The samples prepared were randomly distributed into each experimental group. Specimen Fabrication and Immersion Procedures A nanofilled resin composite (Filtek Z350 XT, 3M ESPE, St. Paul, MN), shade B1E, was used for preparing samples measuring 10 mm in diameter and 2 mm thick, using a two-piece stainless steel matrix with four circular holes (Oliveira et al., 2010). A mylar matrix strip (K-Dent—Quimidrol, Com Ind. Importac¸~ ao Ltda, Joinville, SC, Brazil) and a glass plate were put on the composite resin surface. A 1 kg stainless steel weight was applied for 30 s to allow the removal of excess material and leave the surface smooth and standardized (Badra et al., 2005). Afterwards, the weight and glass plate were removed, and samples were light-cured for 40 s, with Microscopy Research and Technique
INFLUENCE OF LIGHT CURING UNITS AND FLUORIDE MOUTHRINSE
Source Immersion media Light curing units Light curing units 3 immersion media Residual
TABLE 2. Summary of analysis of variance for color change (DE) DF SS MS F 4 1 4 140
9.314 0.458 3.824 54.789
half of the sample being light cured according to each light curing unit selected. The samples were subjected to finishing/polishing procedures with aluminum oxide discs (Super-Snap, Shofu Dental Corp. Kyoto, Japan), 12 mm in diameter, in a decreasing sequence of granulation (Oliveira et al., 2010). Between one granulation and another, the samples were washed with air–water jets for 5 s. At the end of the process, the specimens were placed in an ultrasound (Ultrasonic Cleaner Plus 1440, Odontobr as— Doctors Trade in Eq—Dental Ltd., Ribeir~ ao Preto, Sao Paulo, Brazil) with water, for 30 minutes to remove possible debris deposited on the surface. The samples were immersed in artificial saliva and stored in a Bacteriological oven (EBC1-Odontobras—Comercio de Eq. Medicos-Odontologicos LTDA, Ribeir~ ao Preto, SP, Brazil) and maintained at a temperature of 37 6 1 C for 24 h. In the staining process, the samples were immersed for1 minute, daily, for 60 days, in different media (Table 1). After immersion, the specimens were rinsed in water, and kept in artificial saliva at 37 6 1 C. For the artificial saliva group, the samples were kept at 37 6 1 C, with daily changes of the artificial saliva. Color Assessment The color-change readouts were made using a Colorimetry Spectrophotometer (Color guide 45/0, PCB 6807 BYK-Gardner GmbH Gerestsried Germany— 400–700 nm), with standard lighting D65 on a white background (Campos et al., 2013; Vichi et al., 2004; Mundim et al., 2010; Sarac et al., 2006) according to CIELab system by a properly calibrated examiner (qL 5 0.90; qa 5 0.75; qb 5 0.95) (Campos et al., 2013). In this study, two readouts were made in each test specimen, one before immersion in the solutions began (baseline—24 h after immersion in artificial saliva) and the other after 60 days of immersion. The color change value DE* was calculated according to the following formula (Wyszecki and Siles, 1982): DE* 5[(DL*)2 1 (Da*)2 1(Db*)2]1/2, where L* stands for lightness, a* for green-red (-a 5 green; 1a 5 red) and b* for blue–yellow (-b 5 blue; 1b 5 yellow). Scanning Electron Microscopy (SEM) Two specimens of each group were prepared for SEM analysis after 60 days of immersion in the solutions. To remove debris on the surface, specimens were washed in distilled water followed by washing in deionized water in an ultra-sonic bath (Sonic Clean, D.M.C. Equipamentos, Sao Carlos, SP, Brazil) for 10 min. The samples were coated with 10 nm of gold in a metallizer, Coating System Bal-Tec Med 020 (Bal-Tec, Microscopy Research and Technique
2.328 0.458 0.956 0.391
5.950 1.171 2.443
3
P
gp2
p
0.050 for the different immersion media). The differences between the groups were evaluated by the Tukey test at a 5% level of significance. RESULTS Table 2 shows the analysis of variance for color change (DE). Table 3 presents the mean and standard deviation of color stability (DE) of the specimens according to the immersion media and light curing source. In the color change evaluation, significant difference (P < 0.001) was verified for the factor immersion media, with the specimens immersed in the Oral B solution present a significantly lower degree of color change than those immersed in artificial saliva and in Fluorgard. For the factor light curing source, no significant difference (P 5 0.281) was observed, irrespective
4
A.L.B. MARTINS DE OLIVEIRA ET AL.
Fig. 1. Composite resin immersed in artificial saliva according to light curing units: material observed by SEM (5003).
Fig. 2. Composite resin immersed in manipulated sodium fluoride according to light curing units: material observed by SEM (5003).
Fig. 3. Composite resin immersed in Oral B according to light curing units: material observed by SEM (5003).
of the immersion media studied. There was no significant interaction among the factors (P 5 0.05). The results obtained by SEM of the studied composite resins are shown in Figures 1–5. According to SEM observations, it was noted that there was no difference in the surface analysis of the specimens light cured by different light curing sources, irrespective of the immersion medium. DISCUSSION There are various intrinsic and extrinsic factors pointed out in the literature, as being responsible for color change of composite resin (Bagheri et al., 2005; Colucci et al., 2009; Eldiwany et al., 1995, Ertas et al., 2006; Fontes et al., 2009; Hosoya, 1999; Iazzeti et al.,
2000; Janda et al., 2005; Kolbeck et al., 2006; Mundim et al., 2010; Nasim et al., 2010; Patel et al. 2004; Villalta et al., 2006). In this study, the influence of the intrinsic “light curing source” and extrinsic “immersion media” factors on color change of nanofilled composite resin (Filtek Z350 XT) was evaluated. It could be verified that the factor light curing source did not influence color change (P 5 0.281) and surface morphology of the studied composite resin. Similar results were found by Usumez et al. (2005) and Santos et al. (2010) which emphasize the assertion of CekicNagas et al. (2010) that the LED appliances have been shown to be as good as the halogen light type. According to Janda et al. (2005) and Pires-de-Souza et al. (2007), various factors may influence the color stability of a composite resin, such as the Microscopy Research and Technique
INFLUENCE OF LIGHT CURING UNITS AND FLUORIDE MOUTHRINSE
5
Fig. 4. Composite resin immersed in Fluordent Reach according to light curing units: material observed by SEM (5003).
Fig. 5. Composite resin immersed in Fluorgard according to light curing units: material observed by SEM (5003).
photoinitiator system. The results obtained in this study with regard to the factor light curing source may be justified, considering that camphorquinone is the photoinitiator used in Filtek Z350 XT and that both XL 3000 an d the Ultralume LED 5 have an emission peak coinciding with the absorption spectrum of this photoinitiator. It could be observed that the factor immersion media did not influence the surface morphology of Filtek Z350 XT, however it did affect color stability (P < 0.001). The Oral B solution (DE 5 1.09 6 0.60) showed a higher degree of color stability than artificial saliva (DE 5 1.65 6 0.70) and Fluorgard (DE 5 1.85 6 0.68), being similar to 0.05% sodium fluoridemanipulated (DE 5 1.47 6 0.64) and Fluordent Reach (DE 5 1.51 6 0.55). It is difficult to compare the results obtained in this study with those in the literature because there is a scarcity of studies (Celik et al., 2008; Oliveira et al., 2012) that evaluated the effects of 0.05% sodium fluoride solutions on the color stability and surface morphology of composite resin. Celik et al. (2008) also observed that the Oral B mouthrinse solution did not have a significant influence on the color stability of a nanofilled composite resin. On the other hand, Oliveira et al. (2012) verified that Fluordent Reach promoted a greater degree of surface degradation in the studied resin. The color change of composites depends on the immersion media. Solutions with high pigmentation will promote staining due to pigments adsorption (Domingos et al., 2011). Solutions with alcohol or acidic Microscopy Research and Technique
promote dissolution in the organic matrix and increase the staining susceptibility. In the present study, alcohol-free solutions (Oral B, manipulated fluoride, artificial fluoride), and with alcohol (Fluordent Reach) and with phosphoric acid (Fluorgard) were used. Both the solutions with alcohol and with acid may have a deleterious effect on the structure of the material, due to softening of the resin matrix, which promotes its degradation and increases its susceptibility to staining over the course of time (Bagheri et al., 2005; Colucci et al., 2009; Oliveira et al., 2012; Patel et al., 2004). Although there was a difference in color stability between the solutions with different compositions, the color change did not show values that compromised the composite resin clinically (DE < 3.3) (Iazzeti et al., 2000; Patel et al., 2004; Vichi et al., 2004). In addition, by means of scanning electron microscopy it was verified that the degradation on the material surface was similar for all the immersion media. It is suggested that these results may have occurred as a result of the methodology adopted for the immersion procedures, in which it was opted to simulate a clinical condition of daily mouth washing for a period of 2 months (60 days). REFERENCES Aravamudhan K, Rakowskid D, Fan PL. 2006. Variation of depth of cured intensity with distance using LED curing lights. Dent Mater 22:988–994. Badra VV, Faraoni JJ, Ramos RP, Palma-Dibb RG. 2005. Influence of different beverages on the microhardness and surface roughness of resin composites. Oper Dent 30:213–219.
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Bagheri R, Burrow MF, Tyas M. 2005. Influence of food-simulating solutions and surface finish on susceptibility to staining of aesthetic restorative materials. J Dent 33:389–398. Brandt WC, Schneider LFJ, Frollini E, Correr-Sobrinho L, Sinhoreti MAC. 2010. Effect of different photo-initiators and light curing units on degree of conversion of composites. Braz Oral Res 24:263– 270. Campos J, Oliveira A, Domingos P, Botta A, Garcia P. 2013. Laboratory tests with quality data in dentistry. J Res Dentistry 1:288– 297. Cekic-Nagas I, Egilmez F, Ergun G. 2010. The effect of irradiation distance on microhardness of resin composites cured with different light curing units. Eur J Dent 4:440–446. Celik C, Yuzugullu B, Erkut S, Yamanel K. 2008. Effects of mouth rinses on color stability of resin composites. Eur J Dent 2:247–253. Colucci V, Santos CD, Amaral FLB, Corona SAM, Catirse ABCEB. 2009. Influence of NaHCO3 powder on translucency microfilled composite resin immersed in different mouthrinses. J Esthet Restor Dent 21:242–248. De Oliveira AL, Botta AC, Campos JA Garcia PP. 2014. Effects of immersion media and repolishing on color stability and superficial morphology of nanofilled composite resin. Microsc Microanal 20: 1234–1239. Domingos PAS, Garcia PPNS, Oliveira ALBM, Palma-Dibb RG. 2011. Composite resin color stability: influence of light sources and immersion media. J Appl Oral Sci 19:204–211. Eldiwany M, Friedl KH, Powers JM. 1995. Color stability of lightcured and post-cured composites. Am J Dent 8:179–181. Ertas E, G€ uler AU, Y€ ucel AC, K€ opr€ ul€ u H, G€ uler E. 2006. Color stability of resin composites after immersion in different drinks. Dent Mater J 25:371–376. Fontes ST, Fern andez MR, Moura CM, Meireles SS. 2009. Color stability of a nanofill composite: effect of different immersion media. J Appl Oral Sci 17:388–391. Garcia PPNS, Corona SAM, Palma Dibb RG, Chimello DT, Catirse ABE, Freitas EM. 2002. Effect of fluoride-containing mouthrinses on the translucence of resin modified glass-ionomer cements. Mater Res 5:485–489. Hosoya Y. 1999. Five-year color changes of light-cured resin composites: influence of light-curing times. Dent Mater 15:268–274. Iazzeti G, Burgess JO, Gardiner D, Ripps A. 2000. Color stability of fluoride-containing restorative materials. Oper Dent 25:520–525. Janda R, Roulet JF, Latta M, Steffin G, R€ uttermann S. 2005. Color stability of resin-based filling materials after aging when cured with plasma or halogen light. Eur J Oral Sci 113:251–257. Kolbeck C, Rosentritt M, Lang R, Handel G. 2006. Discoloration of facing and restorative composites by UV-irradiation and staining food. Dent Mater 22:63–68. Martinelli J, Souza FCPP, Casemiro LA, Tirapelli C, Panzeri H. 2006. Abrasion resistence of composites polymerized by light-emitting diodes (LED) and halogen light-curing units. Braz Dent J 17:29– 33.
Mitra SB, Wu D, Holmes BN. 2003. An application of nanotechnology in advanced dental material. J Am Dent Assoc 134:1382–1390. Mundim FM, Garcia LFR, Pires-de-Souza FCP. 2010. Effect of staining solutions and repolishing on color stability of direct composites. J Appl Oral Sci 18:249–254. € Mutlu-Sagesen L, Erg€ un G, Ozkan Y, Semiz M. 2005. Color stability of a dental composite after immersion in various media. Dent Mater J 24:382–390. Nasim I, Neelakantan P, Sujeer R, Subbarao CV. 2010. Color stability of microfilled, microhybrid and nanocomposite resins – an in vitro study. J Dent 385:137–142. Oliveira A, Domingos P, Campos J, Botta A, Garcia P. 2014. Color stability of a nanofilled resin: Influence of polishing and finishing and fluoride solutions according to time. J Res Dentistry 2:119–128. Oliveira AL, Domingos PA, Palma-Dibb RG, Garcia PP. 2012. Chemical and morphological features of nanofilled composite resin: influence of finishing and polishing procedures and fluoride solutions. Microsc Res Tech 75:212–219. Oliveira ALBM, Garcia PPNS, Santos PA, Campos JSDB. 2010. Surface roughness and hardness of a composite resin: influence of finishing and polishing and immersion methods. Mater Res 13:409– 415. Patel SB, Gordan VV, Barret AA, Shen C. 2004. The effect of surface finishing and storage solutions on the color stability of resin-based composites. J Am Dent Assoc 135:587–594. Pires-de-Souza FCP, Garcia LFR, Hamida HM, Casemiro LA. 2007. Color stability of composites subjected to accelerated aging after curing using either a halogen or a light emitting diode source. 2007. Braz Dent J 18:119–123. Santos PA, Garcia PPNS, Oliveira ALBM, Palma-Dibb RG. 2010. Chemical and morphological features of dental composite resin: influence of light curing units and immersion media. Microsc Res Tec 73:176–181. Sarac D, Sarac YS, Kulunk S, Ural C, Kulunk T. 2006. The effect of polishing techniques on the surface roughness and color change of composite resins. J Prosthet Dent 96:33–40. Usumez A, Ozturk N, Ozturk B. 2005. Two-year color changes of light-cured composites: influence of different light-curing units. Oper Dent 30:655–660. Vichi A, Ferrari M, Davidson CL. 2004. Color and opacity variations in three different resin-based composite products after water aging. Dent Mater 20:530–534. Villalta P, Lu H, Okte Z, Garcia-Godoy F, Powers JM. 2006. Effects of staining and bleaching on color change of dental composite resins. J Prosthet Dent 95:137–142. Voltarelli FR, Santos-Daroz CB, Alves MC, Peris AR, Marchi GM. 2009. Effect of different light-curing devices and aging procedures on composite Knoop microhardness. Braz Oral Res 23:473–479. Wyszecki G, Siles WS. 1982. Color science: concepts and methods, quantitative data and formula, New York: John Wiley & Sons. Yap AUJ, Yap SH, Teo CK, Ng JJ. 2004. Comparison of surface finish of new aesthetic restorative materials. Oper Dent 29:100–104.
Microscopy Research and Technique
Influence of Light Curing Units and Fluoride Mouthrinse on Morphological Surface and Color Stability of A Nanofilled Composite Resin ANA LUISA BOTTA MARTINS DE OLIVEIRA,1* ANA CAROLINA BOTTA,2 JULIANA ALVARES DUARTE BONINI CAMPOS,1 AND PATRICIA PETROMILLI NORDI SASSO GARCIA1 1 2
Department of Social Dentistry, Araraquara School of Dentistry, University of S~ ao Paulo State, S~ ao Paulo, Brazil Department of General Dentistry, Stony Brook School of Dental Medicine, New York
KEY WORDS
fluorine; composite resins; color; dental technology; SEM
ABSTRACT Composite resin is a dental material susceptible to color change over time which limits the longevity of restorations made with this material. The influence of light curing units and different fluoride mouthrinses on superficial morphology and color stability of a nanofilled composite resin was evaluated. Specimens (N 5 150) were prepared and polished. The experimental groups were divided according to the type of light source (halogen and LED) and immersion media (artificial saliva, 0.05% sodium fluoride solution-manipulated, Fluordent Reach, Oral B, Fluorgard). Specimens remained in artificial saliva for 24-h baseline. For 60 days, they were immersed in solutions for 1 min. Color readout was taken at baseline and after 60 days of immersion. Surface morphology was analyzed by Scanning Electron Microscopy (SEM) after 60 days of immersion. Color change data were submitted to two-way Analysis of Variance and Tukey tests (a 5 0.05). Surface morphology was qualitatively analyzed. The factor light source presented no significant variability (P 5 0.281), the immersion media, significant variability (P < 0.001) and interaction between factors, no significant variability (P 5 0.050). According to SEM observations, no difference was noted in the surface of the specimens polymerized by different light sources, irrespective of the immersion medium. It was concluded that the light source did not influence the color stability of composite, irrespective of the immersion media, and among the fluoride solutions analyzed, Fluorgard was the one that promoted the greatest color change, however, this was not clinically perceptible. The immersion media did not influence the morphology of the studied resin. Microsc. Res. Tech. 00:000–000, 2014. V 2014 Wiley Periodicals, Inc. C
INTRODUCTION The composite resin is a direct restorative material and it is considered the material of choice whenever esthetic appearance is a concern. However, the composite resin presents some deficiencies that may affect its color stability, compromising the quality and longevity of restorations (De Oliveira et al., 2014). The etiology of color change of composites is multifactorial (Hosoya, 1999; Janda et al., 2005; Kolbeck et al., 2006; Mutlu-Sagesen et al., 2005; Nasim et al., 2010; Patel et al., 2004; Pires-de-Souza et al., 2007; Villalta et al., 2006), and may involve intrinsic (Eldiwany et al., 1995; Hosoya, 1999; Iazzeti et al., 2000; MutluSagesen et al., 2005) and extrinsic factors (Bagheri et al., 2005; Fontes et al., 2009; Iazzeti et al., 2000). The intrinsic factors involved in color stability of resin composites are related to the characteristics of the restorative material. The type of organic matrix, inorganic load particle size and its percentage of the composition are factors that may interfere in the optical properties of composite resin (Bagheri et al., 2005; Hosoya, 1999; Mundim et al., 2010; Mutlu-Sagesen et al., 2005; Patel et al., 2004; Voltarelli et al., 2009). Also as intrinsic factor there is the degree of polymer conversion that according to Patel et al. (2004) and C V
2014 WILEY PERIODICALS, INC.
Usumez et al. (2005), it may also influence the susceptibility to staining of the resin. Therefore, the type of light curing source and power density of the light activation unit play an important role in composite resin color stability (Mutlu-Sagesen et al., 2005; Santos et al., 2010; Usumez et al., 2005). There are various types of light curing sources, with the halogen and light emitting diode—LED type being those most frequently used (Aravamudhan et al., 2006; Cekic-Nagas et al., 2010; Martinelli et al., 2006; Piresde-Souza et al., 2007). Although halogen light appliances are low cost, it emits light within the blue spectrum and the process to obtain it results in an excessive loss of energy in the form of heat, resulting in degradation of the light bulb, reflector and filter over the time (Brandt et al. 2010; Martinelli et al., 2006; Pires-deSouza et al., 2007; Usumez et al., 2005; Voltarelli et al., 2009). The LED units use semiconductors to produce *Correspondence to: Ana Luısa Botta Martins de Oliveira, Orlando Damiano, 2281 S~ ao Carlos, S~ ao Paulo, CEP: 13560-450, Brazil. E-mail: [email protected] Received 1 April 2014; accepted in revised form 31 July 2014 REVIEW EDITOR: Prof. Alberto Diaspro DOI 10.1002/jemt.22421 Published online 00 Month 2014 in Wiley Online Library (wileyonlinelibrary.com).
2 Immersion media
A.L.B. MARTINS DE OLIVEIRA ET AL. TABLE 1. Identification and characteristics of immersion media used in study Manufacturer Flavor Color Composition
Artificial saliva
Santa Paula Pharmacy, Araraquara, SP, Brazil
Flavorless
Colorless
Sodium fluoridemanipulated Fluordent Reach
Santa Paula Pharmacy, Araraquara, SP, Brazil Johnson & Johnson, S~ ao Jos e dos Campos, SP, Brazil
Flavorless
Colorless
Mint
Green
Oral B
Gillette, S~ ao Paulo, SP, Brazil
Mint
Blue
Fluorgard
Colgate, S~ ao Bernardo do Campo, SP, Brasil
Cherry
Red
the blue light, which consume little energy during their light emission process (Martinelli et al., 2006; Pires-de-Souza et al., 2007; Usumez et al., 2005; Voltarelli et al., 2009). Among the extrinsic factors, factors related to the dentist such as finishing and polishing procedures and those related to patient behavior, such as poor oral hygiene and diet based on foods and beverages containing pigments are highlighted (Badra et al., 2005; De Oliveira et al., 2014; Domingos et al., 2011; Mundim et al., 2010; Oliveira et al., 2010, 2014; Patel et al., 2004; Santos et al., 2010). In this context, the use of fluoridated mouthrinses on a daily basis, when routinely used may change the color and surface morphology of composite resins due to their chemical composition (Garcia et al., 2002). The staining susceptibility of microfilled and hybrid composites has been extensively studied in the last years. Moreover, the properties of nanofilled resins need to be investigated further, since they has a higher percentage of load and nanoclusters, capable of improving properties (Mitra et al., 2003; Yap et al., 2004) such as color stability. Although studies assessing staining susceptibility of nanofilled resins in various immersion media have been performed, (De Oliveira et al., 2014; Domingos et al., 2011; Fontes et al., 2009; Oliveira et al., 2012, 2014; Santos et al., 2010) the influence of fluoride mouth rinse solutions on the color stability of nanofilled resins cured by different light sources is unknown. The aim of the present study was to investigate the influence of light curing sources on the color stability
Potassium chloride (0.96 g), sodium chloride (0.67 g), magnesium chloride (0.04 g), potassium phosphate (0.27 g), calcium chloride (0.12 g), nipagin (0.01 g), nipasol (0.1 g), carboxymethyl cellulose (8.0 g), sorbitol (24.0 g) and water (1000 ml). 0.05% Sodium fluoride 0.05% Sodium fluoride, water, glycerin, ethyl alcohol, Poloxamer 407, methylparaben, mint aroma, dibasic sodium phosphate, sucralose, monobasic sodium phosphate, cetylpyridinium chloride, propylparaben, yellow food coloring 5, FD&C food coloring No. 1. 0.05% Sodium fluoride, water, glycerin, PEG-40 hydrogenated castor oil, methylparaben, 0.053% monohydrated cetylpyridinium chloride, sodium saccharin, sodium benzoate, propylparaben, FD&C blue No. 1. 0.05% Sodium fluoride, water, sorbitol, polysorbate 20, potassium sorbate, sodium biphosphate, phosphoric acid, red coloring, aromatic composition.
pH 7.00
5.36 6.96
5.41
4.13
and surface morphology of a nanofilled composite resin, considering the use of fluoridated solutions. MATERIALS AND METHODS This research is a double-blind experimental in vitro study. The dependent variable was the color stability and the independent variables were light curing units (XL 3000/3M-ESPE—480 mW/cm2 and Ultralume LED 5/Ultradent—790 mW/cm2) and immersion media (Table 1). The association between curing light units and immersion media resulted in 10 groups. The number of samples used for each experimental condition was established at 15 (N 5 150). The samples prepared were randomly distributed into each experimental group. Specimen Fabrication and Immersion Procedures A nanofilled resin composite (Filtek Z350 XT, 3M ESPE, St. Paul, MN), shade B1E, was used for preparing samples measuring 10 mm in diameter and 2 mm thick, using a two-piece stainless steel matrix with four circular holes (Oliveira et al., 2010). A mylar matrix strip (K-Dent—Quimidrol, Com Ind. Importac¸~ ao Ltda, Joinville, SC, Brazil) and a glass plate were put on the composite resin surface. A 1 kg stainless steel weight was applied for 30 s to allow the removal of excess material and leave the surface smooth and standardized (Badra et al., 2005). Afterwards, the weight and glass plate were removed, and samples were light-cured for 40 s, with Microscopy Research and Technique
INFLUENCE OF LIGHT CURING UNITS AND FLUORIDE MOUTHRINSE
Source Immersion media Light curing units Light curing units 3 immersion media Residual
TABLE 2. Summary of analysis of variance for color change (DE) DF SS MS F 4 1 4 140
9.314 0.458 3.824 54.789
half of the sample being light cured according to each light curing unit selected. The samples were subjected to finishing/polishing procedures with aluminum oxide discs (Super-Snap, Shofu Dental Corp. Kyoto, Japan), 12 mm in diameter, in a decreasing sequence of granulation (Oliveira et al., 2010). Between one granulation and another, the samples were washed with air–water jets for 5 s. At the end of the process, the specimens were placed in an ultrasound (Ultrasonic Cleaner Plus 1440, Odontobr as— Doctors Trade in Eq—Dental Ltd., Ribeir~ ao Preto, Sao Paulo, Brazil) with water, for 30 minutes to remove possible debris deposited on the surface. The samples were immersed in artificial saliva and stored in a Bacteriological oven (EBC1-Odontobras—Comercio de Eq. Medicos-Odontologicos LTDA, Ribeir~ ao Preto, SP, Brazil) and maintained at a temperature of 37 6 1 C for 24 h. In the staining process, the samples were immersed for1 minute, daily, for 60 days, in different media (Table 1). After immersion, the specimens were rinsed in water, and kept in artificial saliva at 37 6 1 C. For the artificial saliva group, the samples were kept at 37 6 1 C, with daily changes of the artificial saliva. Color Assessment The color-change readouts were made using a Colorimetry Spectrophotometer (Color guide 45/0, PCB 6807 BYK-Gardner GmbH Gerestsried Germany— 400–700 nm), with standard lighting D65 on a white background (Campos et al., 2013; Vichi et al., 2004; Mundim et al., 2010; Sarac et al., 2006) according to CIELab system by a properly calibrated examiner (qL 5 0.90; qa 5 0.75; qb 5 0.95) (Campos et al., 2013). In this study, two readouts were made in each test specimen, one before immersion in the solutions began (baseline—24 h after immersion in artificial saliva) and the other after 60 days of immersion. The color change value DE* was calculated according to the following formula (Wyszecki and Siles, 1982): DE* 5[(DL*)2 1 (Da*)2 1(Db*)2]1/2, where L* stands for lightness, a* for green-red (-a 5 green; 1a 5 red) and b* for blue–yellow (-b 5 blue; 1b 5 yellow). Scanning Electron Microscopy (SEM) Two specimens of each group were prepared for SEM analysis after 60 days of immersion in the solutions. To remove debris on the surface, specimens were washed in distilled water followed by washing in deionized water in an ultra-sonic bath (Sonic Clean, D.M.C. Equipamentos, Sao Carlos, SP, Brazil) for 10 min. The samples were coated with 10 nm of gold in a metallizer, Coating System Bal-Tec Med 020 (Bal-Tec, Microscopy Research and Technique
2.328 0.458 0.956 0.391
5.950 1.171 2.443
3
P
gp2
p
0.050 for the different immersion media). The differences between the groups were evaluated by the Tukey test at a 5% level of significance. RESULTS Table 2 shows the analysis of variance for color change (DE). Table 3 presents the mean and standard deviation of color stability (DE) of the specimens according to the immersion media and light curing source. In the color change evaluation, significant difference (P < 0.001) was verified for the factor immersion media, with the specimens immersed in the Oral B solution present a significantly lower degree of color change than those immersed in artificial saliva and in Fluorgard. For the factor light curing source, no significant difference (P 5 0.281) was observed, irrespective
4
A.L.B. MARTINS DE OLIVEIRA ET AL.
Fig. 1. Composite resin immersed in artificial saliva according to light curing units: material observed by SEM (5003).
Fig. 2. Composite resin immersed in manipulated sodium fluoride according to light curing units: material observed by SEM (5003).
Fig. 3. Composite resin immersed in Oral B according to light curing units: material observed by SEM (5003).
of the immersion media studied. There was no significant interaction among the factors (P 5 0.05). The results obtained by SEM of the studied composite resins are shown in Figures 1–5. According to SEM observations, it was noted that there was no difference in the surface analysis of the specimens light cured by different light curing sources, irrespective of the immersion medium. DISCUSSION There are various intrinsic and extrinsic factors pointed out in the literature, as being responsible for color change of composite resin (Bagheri et al., 2005; Colucci et al., 2009; Eldiwany et al., 1995, Ertas et al., 2006; Fontes et al., 2009; Hosoya, 1999; Iazzeti et al.,
2000; Janda et al., 2005; Kolbeck et al., 2006; Mundim et al., 2010; Nasim et al., 2010; Patel et al. 2004; Villalta et al., 2006). In this study, the influence of the intrinsic “light curing source” and extrinsic “immersion media” factors on color change of nanofilled composite resin (Filtek Z350 XT) was evaluated. It could be verified that the factor light curing source did not influence color change (P 5 0.281) and surface morphology of the studied composite resin. Similar results were found by Usumez et al. (2005) and Santos et al. (2010) which emphasize the assertion of CekicNagas et al. (2010) that the LED appliances have been shown to be as good as the halogen light type. According to Janda et al. (2005) and Pires-de-Souza et al. (2007), various factors may influence the color stability of a composite resin, such as the Microscopy Research and Technique
INFLUENCE OF LIGHT CURING UNITS AND FLUORIDE MOUTHRINSE
5
Fig. 4. Composite resin immersed in Fluordent Reach according to light curing units: material observed by SEM (5003).
Fig. 5. Composite resin immersed in Fluorgard according to light curing units: material observed by SEM (5003).
photoinitiator system. The results obtained in this study with regard to the factor light curing source may be justified, considering that camphorquinone is the photoinitiator used in Filtek Z350 XT and that both XL 3000 an d the Ultralume LED 5 have an emission peak coinciding with the absorption spectrum of this photoinitiator. It could be observed that the factor immersion media did not influence the surface morphology of Filtek Z350 XT, however it did affect color stability (P < 0.001). The Oral B solution (DE 5 1.09 6 0.60) showed a higher degree of color stability than artificial saliva (DE 5 1.65 6 0.70) and Fluorgard (DE 5 1.85 6 0.68), being similar to 0.05% sodium fluoridemanipulated (DE 5 1.47 6 0.64) and Fluordent Reach (DE 5 1.51 6 0.55). It is difficult to compare the results obtained in this study with those in the literature because there is a scarcity of studies (Celik et al., 2008; Oliveira et al., 2012) that evaluated the effects of 0.05% sodium fluoride solutions on the color stability and surface morphology of composite resin. Celik et al. (2008) also observed that the Oral B mouthrinse solution did not have a significant influence on the color stability of a nanofilled composite resin. On the other hand, Oliveira et al. (2012) verified that Fluordent Reach promoted a greater degree of surface degradation in the studied resin. The color change of composites depends on the immersion media. Solutions with high pigmentation will promote staining due to pigments adsorption (Domingos et al., 2011). Solutions with alcohol or acidic Microscopy Research and Technique
promote dissolution in the organic matrix and increase the staining susceptibility. In the present study, alcohol-free solutions (Oral B, manipulated fluoride, artificial fluoride), and with alcohol (Fluordent Reach) and with phosphoric acid (Fluorgard) were used. Both the solutions with alcohol and with acid may have a deleterious effect on the structure of the material, due to softening of the resin matrix, which promotes its degradation and increases its susceptibility to staining over the course of time (Bagheri et al., 2005; Colucci et al., 2009; Oliveira et al., 2012; Patel et al., 2004). Although there was a difference in color stability between the solutions with different compositions, the color change did not show values that compromised the composite resin clinically (DE < 3.3) (Iazzeti et al., 2000; Patel et al., 2004; Vichi et al., 2004). In addition, by means of scanning electron microscopy it was verified that the degradation on the material surface was similar for all the immersion media. It is suggested that these results may have occurred as a result of the methodology adopted for the immersion procedures, in which it was opted to simulate a clinical condition of daily mouth washing for a period of 2 months (60 days). REFERENCES Aravamudhan K, Rakowskid D, Fan PL. 2006. Variation of depth of cured intensity with distance using LED curing lights. Dent Mater 22:988–994. Badra VV, Faraoni JJ, Ramos RP, Palma-Dibb RG. 2005. Influence of different beverages on the microhardness and surface roughness of resin composites. Oper Dent 30:213–219.
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