Cigarette smoke: effects on water sorption and solubility of restorative dental composites Paula Mathias, DDS, MS, PhD n Sara Ramos B. Santos n Thaiane R. Aguiar, DDS, MS, PhD n Poliana Ramos B. Santos, DDS Andrea N. Cavalcanti, DDS, MS, PhD Although scientific evidence has shown the effects of tobacco on changes in the color of composite resins, the association between tobacco exposure and the physical properties of composite resins has not been thoroughly investigated. The purpose of this study was to evaluate the effects of cigarette smoke products on water sorption and solubility of microfilled, microhybrid, and nanofilled composite resins (Durafill VS, Filtek Z250, and Filtek Z350 XT, respectively). Ten discs were prepared of each material and divided into 2 groups (n = 5), according to cigarette smoke exposure. Specimens were first desiccated until a constant mass was obtained (M 1 ). Then half of the samples were immersed in deionized water while the other half were exposed daily to tobacco smoke, then washed and stored in de- ionized water. After 21 days, the resin discs were measured (M 2 ) and placed in desiccators until constant mass was achieved (M 3 ). Water sorption and solubility were calculated and the data was statistically analyzed. Water sorption revealed significant differences among the composite resins. The Filtek Z350 XT exhibited the highest water sorption, followed by Durafill VS and Filtek Z250. Cigarette smoke significantly increased water sorption for all products, but only the solubility of Durafill VS showed a significant dif- ference. Filtek Z250 demonstrated significantly lower solubility than Durafill VS, and Filtek Z350 XT had intermediate values. These results indicated that water sorption and solubility varied among the products, and tobacco smoke may alter the physical properties of resin-based materials. Received: June 18, 2013 Accepted: September 25, 2013 Key words: cigarette smoke, solubility, water sorption, composite resin E sthetics, color stability, and good physicomechanical performance are essential characteristics for a dental restorative composite. 1,2 The clinical behavior of a composite resin is multifacto- rial and has been associated with intrinsic characteristics such as organic composi- tion, type of fillers, coupling agent used, conversion degree, surface roughness, water sorption, and solubility parameters. 3-6 In addition, positive correlations between composite resin and extrinsic stains (such as coffee, tea, orange juice, carbonated drinks, and cigarette smoke) have recently been reported in the dental literature. 1,2,7-9 According to Mackay, the use of tobacco is epidemic and expanding, and even though the harmful effects of tobacco have been well-documented, new risks continue to appear. 10 In restorative dentistry, a new study by Huang et al suggested that smoking can increase the development of caries, and Takeuchi et al reported that byproducts of cigarette smoke were observed in composite resin and dental structures. 11,12 Moreover, Almeida e Silva et al found that contami- nation by cigarette smoke significantly decreased the bond strength between dentin and composite resin following exposure to 30 cigarettes a day for 17 days. 13 However, no association between the physical properties of composite resins and cigarette smoke—which may provide important implications for the clinical longevity of restorative materials—has been investigated until now. The water sorption and solubility properties of resin-based materials have an appreciable effect on the durability of dental restoratives. 2 In the oral environ- ment, these materials may uptake water and suffer chemical degradation from components present in saliva, bever- ages, and foods. 14 These processes may promote a plasticizing effect on restor- ative structures by releasing intrinsic components such as residual monomers and filler particles, negatively affecting the functional lifetime of restorations. 15-17 Water sorption and solubility studies have been carried out after immersion in various solutions such as distilled/deion- ized water, ethanol, and acidic drinks. 2,16-19 However, studies evaluating the effect of tobacco smoke on the water sorption/solu- bility properties of restorative composite resin have not been reported. The objective of this study was to determine the water sorption and solubility characteristics of various types of restorative dental composite Operative (Restorative) Dentistry 54 March/April 2014 General Dentistry www.agd.org Table 1. Specifications of the composite resins. Composite resin (manufacturer) Resin type Shade color Filler content (wt%) Filler type/size Organic matrix (lot number) Filtek Z350 XT (3M ESPE) Nanofilled A3B 78.5 Zirconia/silica clusters 0.6-1.4 μm; silica 5-20nm Bis-GMA, UDMA, Bis-EMA, TEGDMA,(202748, 182351, 182963) Filtek Z250 (3M ESPE) Microhybrid A3 84.5 Zirconia/silica 0.01-3.5 μm Bis-GMA, UDMA, Bis-EMA, TEGDMA (75553BR, 41393BR) Durafill VS (Heraeus Kulzer) Microfilled A3 50.5 Prepolymerized silica 10-20 μm; sílica 0.02-2 μm UDMA (010214, 010213) Abbreviations: Bis-EMA, bisphenol A polyethylene glycol diether dimethacrylate; Bis-GMA, bisphenol A diglycidyl ether dimethacrylate; TEGDMA, triethylene glycol dimethacrylate, UDMA, diurethane dimethacrylate.