Teeth

By 10 weeks gestation, the bud stage begins. Small enamel organs form. These are the early structures from which each tooth will develop.^{2 3}

By about 12 weeks, the cap stage is underway. The tooth germ grows and folds inward. This helps shape the future crown, the part of the tooth seen above the gum. Important cells also begin to specialize. Some will later make enamel. Other nearby cells form the dental papilla, which will become the tooth’s pulp. The bud of a second tooth starts to form behind the first tooth. The second tooth will slowly develop into the permanent adult tooth. The first tooth becomes the baby tooth.^{4 5}

By 16 weeks, the tooth enters the bell stage. More layers appear, and the tooth becomes even more organized. These layers protect the developing tooth, carry nutrients, and help determine its final form, including the root.⁶ The jaw bone forms around the baby tooth and permanent tooth, holding them in place.⁷

Breastfeeding appears to protect against tooth decay during the first year of life, while its effects after age one remain unclear because diet and dental hygiene become increasingly important.¹³ There is no need to stop nursing when a baby’s first teeth come in. In contrast, regularly putting a baby to bed with a bottle may increase the risk of cavities because milk can pool around the upper front teeth for long periods.¹⁴ Surprisingly, the biggest cause of early childhood cavities is often not milk at all, but cavity-causing bacteria passed from caregivers through shared spoons, cups, or pacifiers.¹⁵