It is also normal to have no teeth change at 7 weeks of age. Tooth change is a normal physiological phenomenon related to genes. Clinically, the order of teeth change in the morning and evening, controlled by the genetic material DNA. If the child has not changed teeth at the age of seven, it indicates that the child’s teeth change time is late, so the child usually grows milk teeth time is also later. Tooth change is a normal physiological phenomenon controlled by genes, which is achieved by replacing milk teeth with permanent teeth to adapt to the chewing function in adulthood. The timing and sequence of tooth changes are controlled by the genetic material DNA. Normal children begin to erupt milk teeth at around 6 months of age, while some children do not erupt milk teeth until around 8 to 9 months or even 1 year of age. Children usually start to change their teeth around the age of 6, but it is not necessarily abnormal for them to have not changed their teeth normally beyond the age of 7. Parents can take their children to the stomatology department of a regular hospital for a checkup to see if there is any subsequent eruption of permanent teeth through a full-mouth surface tomogram.