Baby and his grandmother ( notice her black dyed teeth ). The Northern tradition of blackening teeth is discontinued. For centuries, this cultural taste was practiced by Vietnamese women in the North. The process involved a mixing of sap of the Lac tree with lemon. A familiar folk song sums up the old standards of feminine beauty in the following verse:
"I love you, first because you are wearing your hair in a rooster tail;  second due to your charming speech; third, since you've got dimpled cheeks, and fourth because your glossy blackened teeth exceed jet in their beauty"

Throughout the thousand years of Chinese occupation (1st to 10th centuries) despite the occupying forces' attempts to force the Vietnamese to adopt Chinese customs and dress, the Vietnamese refused to stop blackening their teeth. For these oppressed people, teeth blackening symbolised their cultural and ethnic distinction.