The timing of teething in infants needs to be determined based on genetics and development, and the timing of teething is individual for each infant and cannot be generalized. If an infant’s genetics and development are normal, most infants will begin to erupt their first milk teeth around 6 months after birth, and they will be ready by 2.5 years of age. Some infants may take longer to erupt, even at age 1, but most will have 20 teeth by age 3. If an infant is slow to develop or is influenced by genetic factors, the timing of teething can be difficult to determine and requires the advice of a medical professional. If the baby has not erupted after the age of 1 year, he or she can visit a dentist for a detailed examination to determine the cause. In addition, parents need to pay attention to the fact that infants can have their mouths cleaned as soon as teeth emerge to avoid oral diseases such as tooth decay, periodontal disease, gum inflammation and soft tissue herpes.