Ultraviolet-induced fluorescence: shedding new light on dental biofilms and dental caries

T he ultraviolet (UV) spectrum is traditionally divided into three UV bands: UVA (315-400 nm, also termed black light, long wave or near UV), UVB (280-315 nm, also termed middle UV responsible for the sunburn response), and UVC (200-280 nm, also termed short wave UV). Having the lowest photon energy of the three ultraviolet wavebands, UVA has little effect on microbial pathogens and virtually no effect on human tissue with short-term exposures. UVA is the important band in terms of diagnostic applications in dentistry. The ability of UVA to make biological materials fluoresce is well known in medicine and dentistry as well as in industry. For example, UVA sources have application for identifying materials such as dyes, inks, minerals, chemical and various biological materials (such as blood, when used in forensic science). Light in the visible violet and UVA wave bands can also initiate chemical reactions which contribute to the photopolymerization of some dental composite materials, as well as adhesives, coatings, and resins used in fields other than dentistry.