Sometimes, the enamel does not form properly when teeth are forming in the young child; the calcium crystals are not deposited properly in the enamel as the tooth is developing in the gums. In mild cases, the enamel is just discoloured with white or brown internal stains. In more severe cases, the enamel is weak and friable, resulting in pits, or roughness. The dentist will assess if a filling is required in such cases. Pits and roughness on the enamel surface tends to collect bacterial plaque, putting the patient at risk of tooth decay.