Ultraviolet/visible light curing

Introduction from ultraviolet to visible light curing... 

The main chemical difference between the ultraviolet and the visible light curing systems is the photoinitiator which is employed. The ultraviolet systems use aliphatic ethers of benzoin, with the methyl ether being the typical, although not the exclusive, choice. 

Composite resins can be cured using a variety of methods. Intraoral curing can be done by chemical means, where amine—peroxide initiators are blended in the material to start the free-radical reaction. Visible light in the blue (470—490 nm) spectmm is used to intraoraHy cure systems containing amine—quin one initiators (247). Ultraviolet systems were used in some early materials but are no longer available (248). Laboratory curing of indirect restorations can be done by the above methods as well as the additional appHcation of heat and pressure (249,250). 

Photosensitive adhesive formulations based on acrylates, epoxy acrylates, and polyurethane acrylics may be cured by exposure to ultraviolet or visible light. The key... 

Ultraviolet (UV), the most popular of the new cure techniques today, starts at 10 nm and goes up to 400 nm. The commonly found industrial lamps range from 200-400 nm or 0.2-0.4 microns. These lamps have power in the 4-6 electron volt range. The wavelengths of visible light range from 400-1000 nm (0.4-1 micron). 

The polymerization of acrylic monomers is an addition-type reaction and is obtained either at room temperature or by heating. The process is usually speeded up by adding initiators, accelerators and catalysts. Polymerization or curing can also be achieved by ultraviolet (UV) light, visible light or electron beams, in which initiators are not necessary (Bjorkner 1995). 

UV = Ultraviolet radiation exposure Vis. = Visible light exposure. Acrylics. Aerobic = Exposure to the atmosphere. Anaerobics Cat. = Catalytic curing (usually by contact with metallic surfaces or primers). Polyurethanes Temperature, in C. Heat - unstated temperature RF - Radio Frequency,... 

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