Properties of 2,3-butanedione and 1-phenyl-1,2-propanedione as new photosensitizers for visible light cured dental resin composites

Two 1,2-diketones, 1-phenyl-1,2-propanedione (PD) and 2,3-butanedione (BD) were investigated as new visible light photosensitizers for formulating a d ental resin composite of bis-GMA in order to improve the physical propertie s of the resin composite. The results were then compared with those of camp horquinone (CQ), the most widely used photosensitizer. Photodecomposition o f the photosensitizers with and without amine was studied through UV absorp tion spectroscopy. The photopolymerization efficiency of bis-GMA containing the photosensitizer increased with irradiation time and with the amount of photosensitizer. The increase was in the order: ED < CQ < PD. The experime ntal resin composite of bis-GMA containing ED or PD showed better mechanica l properties than that which contained CQ. The reason for the higher mechan ical properties of the resin composite containing ED or PD as compared with that containing CQ is discussed through the study of a model reaction. It was observed that ED or PD serves not only as a photosensitizer but also as a crosslinking agent. (C) 2000 Elsevier Science Ltd. All rights reserved.