Polymerizing Thick Sections of BISGMA and TEGDMA


Efficiency of 4,4′-bis(N,N-diethylamino) benzophenone for the polymerization of dimethacrylate resins in thick sections

Walter F Schroeder, Silvana L Asmussen, Wayne D Cook, Claudia I Vallo

Abstract

The efficiency of 4,4′-bis(N,N-diethylamino)benzophenone (DEABP) for the polymerization of dimethacrylate monomers in thick sections (12 mm) was studied. DEABP (λmax = 365 nm) represents a complete initiating system as it contains both ketone and amine functional groups. During irradiation, DEABP photobleaches at a fast rate causing deeper penetration of light through the underlying layers, but the photoinitiation efficiency (rate of polymerization per photon absorption rate) is relatively poor. As a result, irradiation of methacrylate monomers at 365 nm results in a slow average polymerization rate and a reduced monomer conversion for thick sections due to the light attenuation caused by the high absorptivity of DEABP and photolysis products. These results highlight the inherent interlinking of light attenuation and photobleaching rate in polymerization of thick sections.

Materials

The resins were formulated from blends of 2,2-bis[4-(2-hydroxy-3-
methacryloxyprop-1-oxy)phenyl]propane (bis-GMA)
and triethylene glycol dimethacrylate (TEGDMA) at mass fraction of 70:30.

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