Abstract
The aim of this study was to determine the influence of photoinitiator systems on physical-chemical properties of flowable composites. Conventional (CFC), composed by bisphenol-glycidyl dimethacrylate (BisGMA)+triethyleneglycol dimethacrylate (TEGDMA), and self-adhesive (SAFC), composed by BisGMA+TEDGMA+bis{2-(methacryloyloxy) ethyl} phosphate (2MP), flowable composites were developed. Five photoinitiator systems were tested: camphorquinone (CQ), ethyl-4-dimethylaminobenzoate (EDMAB), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), phenylbis (2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), CQ+EDMAB+TPO and CQ+EDMAB+BAPO. A two-peak LED was used; degree of conversion (DC) and the maximum polymerization rate (RPmax) were determined by near infrared spectroscopy. For the yellowing degree a spectrophotometer was used. Water sorption (Wsp) was obtained after 30 days of water storage (n=5). Data were submitted to two-way analysis of variance and Tukey's test (a=0.05). BAPO presented the highest DC and RPmax values for both series. SAFCs presented lower DC and RPmax for CQ+EDMAB-based materials. Greater yellowing was observed for SAFCs compared with CFCs, except for BAPO. Greater Wsp was observed for SAFCs compared with CFCs. The photoinitiator did not influence Wsp for CFCs, but TPO and BAPO presented the highest Wsp in SAFCs. The photoinitiator system affected differently the physical-chemical properties of CFCs and SAFCs.
Highlights
Low-viscosity resin composites were introduced in Dentistry in 1996 (1)
Assuming that the same could be applied to self-adhesive composite, the purpose of this study was to determine the influence of different photoinitiator systems on the physicalchemical properties of two flowable resin composites types, conventional or self-adhesive, evaluated by the degree of C=C conversion, maximum polymerization rate, yellowing effect and water sorption
This present study was conducted in order to evaluate the physical-chemical properties of model self-adhesive and conventional resin composites with different photoinitiator systems
Summary
Low-viscosity resin composites were introduced in Dentistry in 1996 (1). The current novelty in adhesive dentistry is the development of self-adhesive flowable composites (SAFCs) to reduce the clinical time and to decrease the technique sensitivity (3). The SAFCs formulation is based on both conventional methacrylate system and acidic monomers bonding technology derived from self-etching adhesive systems (2). The acidic functional monomers are predominantly methacrylate acid-derivatives, such as 4-methacryloxyethyl anhydride trimellitate acid (4-META), or phosphonate monomers derivatives, such as 2-methacryloxyethyl phenyl phosphate (phenyl-P), methacryloyloxydecyl dihydrogen phosphate (10-MDP), and bis[2-(methacryloyloxy) ethyl] phosphate (2MP) (4). The acidic monomers are capable of chemically interacting with calcium from the tooth substrate, leading to ionic bond (5). Their low pH may neutralize the tertiary amine by an acid-base reaction, decreasing the composites’ polymerization (6). The acidic monomers are more hydrophilic and possibly influenced the increase of water absorption by the polymer
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