DETERMINATION OF RADIATION ENERGY EMITTED BY LIGHT ACTIVATION UNITS

Since the introduction in the 1970s of single paste composite material s, there has been a rapid increase in the range of both materials and activation light units. This investigation is being undertaken as part of a larger study where the characteristics of both composite materia ls, light activation units and composite material/light activation uni t combinations, are being evaluated. This section of the study was und ertaken to determine the characteristics of four light activation unit s. The equipment was developed to measure radiation energy over a wide range of illumination. This range can be from the relatively low inte nsity of radiation transmitted through restorative materials to the in tensities of direct radiation from light activation units. The four li ght units tested had various radiation outputs between 2250001x and 75 0001x. All the units, apart from one, showed a decrease in light outpu t with successive applications. The units emitted radiation outside th e optimum range of 440 - 500 nm, which may produce damaging radiation and glare. Although the extreme intensities varied threefold the effec t on depth of cure of one material varied by only 16%.