A review of the development of radical photopolymerization initiators used for designing light-curing dental adhesives and resin composites

Abstract

This paper reviews our recent studies on radical photopolymerization initiators, which are used in the design of light-curing dental adhesives and resin composites, by collating information of related studies from original scientific papers, reviews, and patent literature. The photopolymerization reactivities of acylphosphine oxide (APO) and bisacylphosphine oxide (BAPO) derivatives, and D,L-camphorquinone (CQ)/tertiary amine were investigated, and no significant differences in degree of conversion (DC) were found between BAPO and CQ/amine system (p>0.05). In addition, a novel 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carbonyldiphenyl phosphine oxide (DOHC-DPPO=CQ-APO) was synthesized and its ultraviolet and visible (UV-VIS) spectral behavior was investigated. CQ-APO possessed two maximum absorption wavelengths (λmax) at 350-500 nm [372 nm (from APO group) and 475 nm (from CQ moiety)], and CQ-APO-containing resins exhibited good photopolymerization reactivity, excellent color tone, relaxed operation time, and high mechanical strength. It was also found that a newly synthesized, water-soluble photoinitiator (APO-Na) improved adhesion to ground dentin.

The role of functional phosphoric acid ester monomers in the surface treatment of yttria-stabilized tetragonal zirconia polycrystals

“…MDP is one of the most frequently used phosphate functional monomers and was originally designed to enhance bond strength to tooth substrate and non-precious metal alloys. Similar to the interaction of phosphoric functional monomers with hydroxyapatite 15,16) , a chemical interaction is believed to occur between the functional monomer and the hydroxyl group of metal ions on the ceramic surface 17) . Kern et al 18) reported that a combination of alumina particle air abrasion and priming with MDP-containing primers provided durable, long-term bonding to dental zirconia ceramics.…”

Effect of new light curing units on microleakage and microhardness of resin sealants

“…Dental visible light curing materials generally contain a diketone-type photoinitiator that absorbs light in the 400-to 500-nm range covered by the blue light from the visible spectrum. The studies showed that the emission peak of blue LED at 465 nm coincided with the absorption peak of camphoroquinone (CQ) at 467 nm 8,15) , but when the resin material contains new photointiators that absorb light energy in lower regions of visible spectrum early generation LED lights failed when compared with QTH 16) . Interestingly, rapid cure did not have an adverse effect on Valo XP group's microleakage values.…”

“…It is estimated at about 180 teeth with a 90% confidence interval level and a standard error of 5%. Caries-free, extracted for orthodontic reasons human mandibular third molars were collected from healthy children ages [15][16][17][18][19][20]. Participants signed the informed consent form.…”

Effects of Third-generation LED LCU on Nanomechanical Properties of Orthodontic Adhesives

“…Polymerization performance may change, depending on the material to be cured, as well as the light source [19]. However, there is very limited number of studies available, providing information about influence of third-generation LED LCUs on LCR.…”