Easyshade Spectrophotometer Accuracy and Precision in Shade Guide Measurements

Determination of tooth color is a crucial step in esthetic dentistry. Therefore, new methods for color evaluation with the use of spectrophotometers have arisen with the claimed advantage of being more objective and reliable. Nevertheless, studies determining a precise match between shade tabs and the spectrophotometric tab readings are scarce but needed in order to better understand their real clinical utility.

Objectives: To examine the sensitivity, specificity and precision of a Vita Easyshade spectrophotometer (ES) in the determination of each color tab of  Vitapan Classical (VC) and Vitapan 3D Master (VM) shade guides.

Methods: Complete shade tabs of VC and VM shade guides were measured according to manufacturers instructions for shade tab measurement by holding the probe tip at 90° to surface at the middle 1/3 of the tab. Two calibrated operators made ES measurements 30 consecutive times for each tab. Between 2 measurements on each tab, the operators had to completely remove the probe tip from the shade tab. Color values were obtained on the bench with specular-excluded, 5mm port, D65 illumination and 2^o observer. Sensitivity, Specificity, Predictive Negative Value (PNV), Predictive Positive Value (PPV) and Kappa factor for agreement were calculated for each color tab of VC and VM. Chi-square test was used for comparison between groups and significance was set at α=0,05.

Results:

Conclusions:

1.     The ES showed good overall performance yelding high values for all parameters in both VC and VM.

2.     The ES measurements showed lower precision and accuracy for VM when compared to VC which can lead to deviations with clinical impact in some colors, probably due to a wider range of shades included in the VM.