The yellowing of 2-year-old baby teeth is mainly caused by tartar or dental defects, dental scaling or dental defect filling and restoration treatment must be carried out. 1. Tartar: poor oral hygiene of babies can lead to the accumulation of food debris and bacterial products on the surface of the teeth, which will make the teeth appear tartar or calculus and other yellow substances; we must keep the oral cavity clean, use the correct way of brushing, and can cooperate with dental scaling treatment, which can effectively remove the yellow substances on the surface of the teeth. 2. Teeth chipped: congenital enamel underdevelopment or dental caries will lead to tooth surface hard tissue defects, and thus the yellow dentin exposure and make the teeth yellow; must be filled with dental restorative treatment, through the oral resin and other materials to repair the missing part of the teeth. 2-year-old baby teeth yellow recommended to consult a doctor for a clear diagnosis and symptomatic treatment, in order to avoid delaying the condition.