Clinical assessment of dental color during dehydration and rehydration by various dental photography techniques

Dental color selection is an important clinical challenge in restorative dentistry due to the alterations related to dehydration and rehydration. This clinical study aimed to quantitatively monitor the color changes between different levels of tooth dehydration and rehydration using different dental photography techniques. Color assessments of the right central incisor were performed using a hybrid-type clinical spectrophotometer (RayPlicker; RP) as control, a dental photography kit (DP), and a mobile dental photography kit (MDP). Cross-polarization filter (CP) and white balance card (WB) were also used in combinations with DP and MDP. Therefore, the effectiveness of eight different photography techniques (DP, DP-WB, DP-CP, DP-WB-CP, MDP, MDP-WB, MDP-CP, and MDP-WB-CP) were investigated. The color measurements during dehydration (at initial, 1, 2, 3, 5, and 15 min) and rehydration (at 30, 60 min, and 24 h) were performed with all techniques. Color changes (∆E₀₀*) were calculated according to the CIEDE2000 formula by comparing the outcomes with the initial values. Regarding the dehydration values by RP, the color changes until the 3rd min were imperceptible (∆E < 0.8) and significantly lower than the 5th min (p < 0.001). The changes were perceptible but acceptable at the 5th min, while it was not even acceptable (∆E ≥ 1.8) at the 15th min. Regarding the rehydration values by RP, the color changes were perceptible and significantly higher at the 30th and 60th min than at the 24th h (p < 0.001). The color changes for 70% of the teeth were below 0.8 at the 24th h. Very high agreements were observed between the assessments by DP/CP, DP/WB/CP, MDP/CP, and MDP/WB/CP techniques, and the RP (p < 0.001 for each assessment method). The clinical color change was considered imperceptible until 3 min of dehydration. However, it became perceptible after 5 min of dehydration and not clinically acceptable after 15 min. Following 15 min of dehydration, the natural tooth color may not be completely reversed even after rehydrating for 24 h. CP filters were considered essential tools when using dental photography or mobile dental photography devices for dental color assessment.