The average 15-month-old baby will have 8-12 teeth, depending on the baby’s condition. Most babies start teething at 6-8 months of age. At 15 months, a baby’s teething includes four upper and lower incisors, four upper and lower lateral incisors, and possibly four first molars. Babies mostly teethe in sequence, with the top two and bottom two incisors, also known as the central incisors, emerging from 6-8 months, the top two and bottom two lateral incisors from 8-12 months, the first milk molar from 12-16 months, the first milk molar from the upper and lower teeth, the milk cusp from 16-20 months, and the second milk molar from the upper and lower teeth from 20-30 months. There are many factors that affect baby’s teething, such as congenital factors, acquired environment, systemic diseases, trauma and infection, etc., all of which can cause variability in the timing of tooth growth. In our daily life, we can help the growth of baby’s teeth through diet, such as feeding semi-solid food, granular food, etc. to help exercise baby’s chewing ability; feeding foods with high nutritional value, protein and calcium-rich food to help baby’s teeth grow normally. In addition, keeping the baby’s mouth clean is also beneficial to the growth of teeth.