Modeling the Relationship Between Tooth Color and Skin Color in Equations to Predict Tooth Color

Abstract

Background Color selection for discolored teeth or for edentulous patients is a subjective process in dentistry. To the best of the authors' knowledge, there is no objective method for tooth color selection for edentulous patients. Several studies have investigated the relationship between tooth color and skin color and the ability to use skin color as a guide to select tooth color in dental rehabilitation cases. The objective of this study was to find and model the relationship between tooth color and skin color in equations to be able to predict tooth color by assessing skin color. Methodology This study was done on 150 participants with equal gender distribution. Digital photography with soft boxes and strobe lights were used to measure tooth and skin color. Digital photography was performed in a dark room with controlled and measured lighting sources and strength. A calibration board was used to create two calibration profiles in software. All photos were calibrated in Adobe Lightroom software. Then, color measurement was done using Adobe Photoshop software in the Commission International de I'Eclarirage (CIELab) system. Results There were positive significant relationships in color spaces L* and a* between tooth color and skin color, and an inverted significant relationship in color space b* between tooth and skin. Three equations with excellent reliability were formulated in this study to predict tooth color by assessing skin color. Conclusions The relationship between tooth color and skin color was modeled in three equations. For edentulous patients, this research might be useful in detecting the proper tooth color and transferring the CIELab color data to dental technicians for further processing. Computerized shade matching and prediction dental software may be designed using these equations.

Keywords: dental color measurement; dental photography; digital color measurement; esthetics dentistry; skin color; tooth color; tooth color measurement; tooth rehabilitation.

Figure 1. Tooth photography: during this procedure, a cheek retractor was used to retract the cheek.

Figure 2. Distance, angulation, and position of the light, camera, and participant for face photography.

Figure 3. Distance, angulation, and position of the light, camera, and participant for tooth photography.

Figure 4. An assistant holding ColorChecker in front of the participant’s face under the settings of face photography. This photo is considered the reference photo for color calibration for face photographs.