A method to evaluate the accuracy of dental color-matching machine

Objectives:Many color matching machines used in dentistry was developed. But evaluation of the accuracy of these machines was affected by many factors such as the quality(stability and accuracy) of the available shade guides. The aim of this study was to find the more accurate way to evaluate the dental color-matching machines.

Methods:The Munsell color tabs between the range of the natural human teeth(6YR~9.3Y) was mesured with the tooth color-matching machine Shade-Eye NCC (Shofu, Japan), and the measured value was compared with the standard value of VITA shade guide to choose the most adjacent tab. The result was compared with the one chosen by the machine to evaluate the accuracy of the machine.

Results:The measured DE value was acceptable(DE<3.7) by using the analyzed mode showing L*,a*,b* compared with the standard value of the Munsell color tabs.But the color tabs chosen by the machine with the VITA notation was not the one with the smallest DE compared with the Munsell tab.

Conclusions:The color matching machine(ShadeEye NCC) can make precision color measurement between the range of the natural human teeth, but the way it transform into VITA notation should be adjusted to get more accurate result. Other teeth color matching machine could be tested with this method to decrease the error caused by the teeth color shade guides.