Effect of spinach leaf (Amaranthus hybridus L.) extract solution and milk on the level of dental discoloration due to coffee

Coffee is a popular drink that can cause teeth discoloration. Milk is high in calcium. Oxalic acid from spinach can react with calcium to form calcium oxalate crystals. We analyzed the level of tooth discoloration due to coffee. Specimens of 24 teeth were divided into a control and three test groups. The test groups were immersed in 10%, 20%, and 30% spinach leaf extract solution plus milk for 60 min and then in coffee for 24 h. The teeth-color change was measured using the VITA Easyshade® device. A significant difference in ΔL* color value was noted in all extract groups, in Δa* of the 10% and 20% groups, and ΔE in the 20% group compared with controls. No group showed a difference in Δb*. There was no significant correlation between extract concentration and ΔL*, Δa*, Δb*, or ΔE. Spinach leaf extract solution and milk can decrease the level of tooth discoloration due to coffee, but there is no significant correlation between extract concentration and the level of tooth discoloration.