High-performance photoinitiating systems for new generation dental fillings

Objectives

To obtain new generation dental composites with improved performance properties compared to currently available dental fillings on the market and to determine the influence of new initiating systems on final product parameters such as degree of cure, hardness, color, and shrinkage.

Methods

In order to verify the effectiveness of the developed initiating systems, typical spectroscopic, electrochemical, and kinetic studies using the real-time FT-IR method were shown. Moreover, paste dental fillings were prepared, the compositions were irradiated with the dental lamp, and the degrees of cross-linking were measured by Raman spectroscopy. The polymerization shrinkage was also determined using the rheometer. In addition, their hardness was examined on the Shore scale. Finally, the color analysis of the composites in the L*a*b* color space was compared with the VITA CLASSIC colorant.

Results

It was shown that, due to their excellent spectroscopic and electrochemical properties, new quinazolin-2-one can act as co-initiators in cationic and radical photopolymerization. It was demonstrated that the most effective composite containing the initiator system in the form of 3-SCH₃Ph-Q, IOD, MDEA, and an inorganic filler as nanometric silica and a bonding agent is cured more than 90% after just 1 cycle of dental lamp exposure (30 s), the hardness of the composite after curing on the Shor Scale is 82 ± 4, and the polymerization shrinkage is less than 2.8%.

Significance

The article demonstrates effective new initiator systems as an alternative to CQ/amine for obtaining new-generation dental composites. The developed dental composites are a big competition to the currently used dental fillings on the market.