The fact that 10 months old babies are not yet teething is related to individual development, dietary habits and vitamin D deficiency. Most babies start to show their first teeth at 4~6 months, but due to individual differences, some babies can show their teeth at around 3 months or 1 year old, so it is normal for 10-month-old babies to have no teeth, so you can observe them first. Furthermore, the baby’s diet is relatively fine, the gums lack of stimulation, but also easy to lead to the late eruption of teeth. If the lack of calcium is serious it will lead to rickets. Vitamin D deficiency leads to malabsorption of calcium, which causes severe calcium deficiency. This can lead to rickets in babies, which can also affect tooth eruption at this time.