Photopolymerization of N,N-dimethylaminobenzyl alcohol as amine coinitiator for light-cured dental resins

WALTER F. SCHROEDER, WAYNE D. COOK, CLAUDIA I. VALLO

DENTAL MATERIALS

Elsevier

Lugar: Manchester; Año: 2008 vol. 24 p. 686 - 693

0109-5641

N,N-dimethylaminobenzyl alcohol (DMOH) was synthesized and used as co-initiator for the photo-polymerization of a model resin based on Bis-GMA/TEGDMA. The DMOH/Benzoyl peroxide redox system, has been recently proposed as a more biocompatible accelerator for the polymerization of bone cements based on poly(methyl methacrylate) because cytotoxity tests have demonstrated that DMOH possesses better biocompatibility properties compared with traditional tertiary amines.  The present study was carried out in order to assess the suitability of DMOH as co-initiator of light-cured dental resins. Experimental formulations containing Camphorquinone (CQ) or 1-phenyl-1,2-propanedione (PPD) in combination with DMOH at different concentrations were studied. The photopolymerization was carried out by means of a commercial light-emitting-diode (LED) curing unit. The evolution of double bonds consumption versus irradiation time was followed by Near-infrared spectroscopy (NIR).  The results obtained in the present study reveal the suitability of the CQ/DMOH initiator system for the polymerization of light-cured dental composites. DMOH is an efficient photoreducer of CQ and PPD resulting in higher polymerization rate and higher double bond conversion compared with DMAEMA.  However, the polymerization initiated by PPD progressed at a lower rate and exhibited lower values of final conversion compared with the resins containing CQ. The photon absorption efficiency (PAE) of the photopolymerization process was calculated from the spectral distribution of the LED unit and the molar absorption coefficient distributions of PPD and CQ. The PAE for PPD was higher than that for CQ. This observation indicates that the lower reactivity of the PPD/amine system should be explained in terms of the mechanism of generating radicals by PPD, which is less efficient compared with CQ. Keywords: Dental restorative material, Photopolymerization; Acrylics; Biocompatibility