Effect of delivering light in specific narrow bandwidths from 394 to 515 nm on the micro-hardness of resin composites

Objectives tudy investigated the wavelength-dependent photosensitivity of eleven resin composites (Admira A2, Heliomolar A2, Herculite XRV A2, Pyramid Dentin A2, Solitaire 2 A2, Z250 A2, Ælite LS A2, Vit-l-escence A2, Tetric Ceram Bleach XL, Tetric Ceram A2, Pyramid Enamel Neutral). s composites 1.6 mm thick were exposed to narrow bandwidths of light at the following peak wavelengths: 394, 400, 405, 410, 415, 420, 430, 436, 442, 450, 455, 458, 467, 470, 480, 486, 493, 500, 505, and 515 ± 5 nm. A spectroradiometer was used to ensure that the same irradiance (mW/cm2) and total energy density (J/cm2) was delivered through each filter. For each resin composite, three specimens were exposed through each filter. The Knoop micro-hardness at the top and bottom of the composites was then measured. The wavelength-dependent photosensitivity of each resin composite was analyzed by plotting the mean hardness achieved at each wavelength. s mposites responded variably when they received light through the narrow bandpass filters. Six resin composites had a single peak of wavelength-dependent photosensitivity at ∼470 nm. Four resin composites had two peaks of wavelength-dependent photosensitivity at ∼470 and ∼405 nm. One resin composite had a single peak of wavelength-dependent photosensitivity at ∼405 nm and was only sensitive to light below 436 nm. icance light delivered through narrow bandpass filters is a convenient method to determine the wavelength-dependent photosensitivity of resins and can be used to predict the performance of dental curing lights.