1�C0 6��m These filler distribution ensures that a polished surf

1�C0.6��m. These filler distribution ensures that a polished surface BMS-907351 can be obtained. More recently, materials formulated with nanoparticles were introduced in the market. According to the manufacturers, this type of materials is able to ensure good polishing and long-term gloss [22]. 2.1.2. The Resinous Matrix The resin matrix usually consists of organic monomers, photoinitiators, coinitiators, inhibitors of polymerization, UV-stabilizers, and small amounts of additional components that vary according the manufacturer. The organic monomers are added in the fluid state and are converted into rigid polymers through a polymerization process, during the material’s clinical application. The polymerization process will be discussed in the next section.

At this point, we will discuss the characteristics of the different monomers used by the manufacturers, since they are directly related with the final polymer properties [23]. The traditional monomers used in Inhibitors,Modulators,Libraries dental composites are shown in Figure 4. Inhibitors,Modulators,Libraries Since the introduction of resin composites in the market, the Bis-GMA (2,2 bis[4-2(2-hydroxy-3-methacryloyloxypropoxy)-phenyl] propane) has been widely used in the formulations of dental resin composites [24]. This molecule has a stiff bisphenol A core, that negatively affects the degree of conversion [25], and Inhibitors,Modulators,Libraries two pendant hydroxyl groups that are able to form strong hydrogen bonds [26] and, as a consequence, makes the resin viscosity very high��500000�C800000mPa.s [27]. Due to the very high molecular weight (512g/mol), the BisGMA provides lower polymerization shrinkage than other monomers and superior mechanical qualities [28].

Consequently, due to its very high viscosity, the amount of fillers added to the mixture and the handling properties might be affected. Therefore, diluent monomers have to be used, or other ones have to substitute the BisGMA, to make the Inhibitors,Modulators,Libraries resin Inhibitors,Modulators,Libraries more fluid [28]. Figure 4 Resin monomers often used in the formulations of dental resin composites. The triethyleneglycol dimethacrylate (TEGDMA) presents a much lower viscosity (100mPa.s) [27] than BisGMA and, thus, is frequently used as an efficient diluent monomer in dental resin composites. The high flexibility of TEGDMA is a consequence of its low molecular weight structure (286g/mol) and also compensates the rigidity of BisGMA and, therefore, the addition of TEGDMA results in resins with higher conversion rate [29].

However, as negative effects, the addition of TEGDMA to the resin Dacomitinib formulation is responsible for an increase of the water sorption by the material [30] and shrinkage. Although BisGMA and TEGDMA are the most traditional monomers used in the formulation of dental resin composites, some others may also be used. The urethane dimethacrylate (UDMA) is a molecule that can be used alone with TEGDMA, or associated with BisGMA and/or some other monomers.

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