1. J Dent Res. 2010 Dec;89(12):1494-8. Epub 2010 Oct 12.

Irradiation modes' impact on radical entrapment in photoactive resins.

Leprince JG, Lamblin G, Devaux J, Dewaele M, Mestdagh M, Palin WM, Gallez B,
Leloup G.

School of Dentistry and Stomatology, Université catholique de Louvain, Brussels, 
Belgium. julian.leprince@uclouvain.be

Different irradiation protocols are proposed to polymerize dental resins, and
discordances remain concerning their impact on the material. To improve this
knowledge, we studied entrapment of free radicals in unfilled Bis-GMA/TEGDMA
(50:50 wt%) resin after light cure. The tested hypothesis was that various
irradiation parameters (curing time, irradiance, and radiant exposure) and
different irradiation modes (continuous and pulse-delay) led to different amounts
of trapped free radicals. The analysis of cured samples (n = 3) by electron
paramagnetic resonance (EPR) revealed that the concentrations of trapped free
radicals significantly differed according to the curing protocol. When continuous
modes with similar radiant exposure were compared, higher concentrations of
trapped free radicals were measured for longer times with lower irradiance.
Concerning pulse modes, the delay had no influence on trapped radical
concentration. These results give new insights into the understanding of the
photopolymerization process and highlight the relevance of using EPR when
studying polymerization of dimethacrylate-based materials.


PMID: 20940363 [PubMed - indexed for MEDLINE]