Abstract
This study investigated the in vitro performance of the commercial bis-acryl composite resins Systemp C&B II (SYS, Ivoclar Vivadent), Protemp 4 (PT4, 3M ESPE), Structur 2C (ST2, Voco) and ProviPlast (PVP, Biodinamica). Characterization involved optical (color stability, translucency parameter, fluorescence), surface (roughness, morphology and elemental composition), physical-chemical (viscosity, polymerization kinetics) and mechanical analyses (Poisson ratio, biaxial flexural strength, flexural modulus). Most tests were carried out after 24 h, but optical and mechanical analyses were carried out after storage in water at 37 °C for 1, 15, and 30 days. Data were statistically analyzed (a=0.05). Most results were material dependent. SYS and PT4 showed stability in color and translucency over time. All materials had similar or higher fluorescence than human enamel. SC2 and PVP showed rougher surfaces than the other bis-acryl composites. Smaller filler particles were observed on the surface of PT4 and PVP compared with the coarser particles from ST2 and SYS. Viscosity readings indicated a thixotropic behavior for all tested materials. SYS had the lowest and PT4 the highest degree of C=C conversion after 10 min. In the polymerization kinetics, PT4 had the highest maximum polymerization rate and reached earlier the transition between polymerization autoacceleration and autodeceleration. PT4 and SYS had significantly higher flexural strength and modulus than ST2 and PVP for most storage times. Results for Poisson ratio varied between materials. Longer storage periods were generally associated with higher frequency of catastrophic failures in the flexural tests. In conclusion, the performance of bis-acryl composite resins varied largely among materials.
Highlights
Provisional restorations are important for the success of many restorative clinical procedures, including the definition of restoration color, shape and contour, in complex restorative rehabilitations [1]
For decades the material used for preparing provisional restorations was auto polymerizing poly(methyl) methacrylate (PMMA), which is commercially available as powder and liquid
The fluorescence of PVP was significantly higher than the other materials and it remained stable with time
Summary
Provisional restorations are important for the success of many restorative clinical procedures, including the definition of restoration color, shape and contour, in complex restorative rehabilitations [1]. For decades the material used for preparing provisional restorations was auto polymerizing poly(methyl) methacrylate (PMMA), which is commercially available as powder (polymer) and liquid (monomer). Unlike PMMA, bis-acryl composite resins contain divinyl methacrylate monomers and filler particle loading [3]. Polymerization shrinkage and exothermic release are potentially reduced, and color stability is improved compared with PMMA [4,5,6]. Bis-acryl composite resins are commercially available for use with automix syringes, increasing costs but with easy handling and reducing air entrapment. According to manufacturers and a few studies in the literature, these materials may present other improved characteristics compared with PPMA, including higher abrasive resistance and esthetics, lower marginal misfit, lower free monomer elution and improved repair potential [7,8,9,10,11,12,13].
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