While a newborn’s smile is typically toothless, the foundation for both sets of teeth is already present within the jawbones. Humans are not born with visible teeth, but with the beginnings of their primary (baby) teeth and permanent (adult) teeth. This process of tooth development starts long before birth and continues throughout childhood, culminating in a complete adult dentition.
The Genesis of Your Teeth
Tooth development begins early in prenatal life. Around five to six weeks into pregnancy, tiny structures called tooth buds, the earliest forms of teeth, start to appear in the embryo’s jawbones. By eight weeks of gestation, ten tooth buds for the primary teeth are established in each arch of the jaw. These buds represent the initial blueprint for the twenty primary teeth a child will eventually have.
Calcification, the process where hard tissues like enamel and dentin form, begins for primary teeth between 13 to 16 weeks in utero. By 18 to 20 weeks, all primary teeth have started this hardening process. The buds for the permanent teeth also begin to form around the time of birth, with the first permanent molars starting their calcification then. These structures remain embedded within the jawbones, unseen beneath the gums.
From Primary to Permanent Teeth
The first primary teeth typically begin to emerge around six months of age, though this can vary. This eruption continues until most children have a full set of twenty primary teeth by approximately two and a half to three years old. These primary teeth serve several important functions, including enabling a child to chew food, aiding in clear speech, and maintaining proper space for the subsequent permanent teeth.
Around six years of age, primary teeth begin to loosen and fall out, making way for the permanent teeth. This shedding occurs as developing permanent teeth beneath them gradually resorb the roots of the primary teeth, pushing them out. The first permanent molars often erupt around six to seven years, appearing behind the existing primary teeth rather than replacing any.
The remaining permanent teeth, including incisors, canines, and premolars, then erupt into the spaces left by the shed primary teeth. This transition period, where both primary and permanent teeth are present, typically lasts until 12 to 13 years of age, when most primary teeth have been replaced. A complete adult dentition usually consists of 32 permanent teeth, including wisdom teeth, which may erupt between 17 and 21 years of age, or sometimes not at all.