Abstract:

Objective

Optical parameters of a self-developed white Light-Emitting Diode（LED）array are measured to understand their impacts on colour values of shade guide for dental application. It is to provide data reference for portable LED shade guide light source.

Methods

White light source with continuous spectrum having 5500 K colour temperature is maded by coating yttrium aluminate garnet（YAG） on the surface of GaN LED array， which has emission wavelength at 450 ～470 nm range， and using certain percentage red phosphor silicate for colour temperature tuning. Optical parameters of such LED are measured by an integrating sphere with 4π structure. The results are compared with that of D55 standard light. This LED light source is also compared with D65 standard light by observing their impacts to CIE L^*， a^*， b^*colour values of three commonly dental used Vita 3D Master and Vita Classia shade guide. Their differences of ΔE^*₉₄ are compared.

Results

The result shows the self-developed LED light source has optical flux φ=389.90 lm， chromaticity coordinates x=0.3342， y=0.3335， colour value Tc=5453 K， emission wavelength λd=600.2 nm， peak wavelength λp=455.0 nm， half-width Δλp=25.6 nm， colour rending index （CRI） Ra=95.3. The same mean colour value of L^*， a^*， b^*of three VITA 3D Master and VITA Classial under the same light source has no statistical differences. The colour differences， which are mean ΔE^*₉₄， of VITA 3D Master and VITA Classial under different light sources are 1.58 NBS and 0.96 NBS，respectively.

Conclusions

Self-developed LED light array meets requirement of both colour temperature and CRI of D55 standard light. Therefore， it can be used on dental application to replace natural sun light as a reconstructed light source.

Key words: Light-Emitting Diode, Tooth shade guide, Lights, Colour