Sixth-age teeth tend to grow at the age of 5 to 7 years, and are called sixth-age teeth because they tend to erupt around the age of 6. A person will have two sets of teeth, milk teeth and permanent teeth, and will go through the stage of replacing milk teeth with permanent teeth. Permanent teeth erupt around the age of 5 to 7 years old, and the first permanent tooth, the first permanent molar, or sixth tooth, usually erupts around the age of 6 years old, after the second milk molar. At the same time, the permanent mesial incisors erupt, the milk mesial incisors are lost, and the other milk teeth are replaced one by one by the permanent teeth in the same position during the following 6 to 12 years of age. The eruption of six-year-old teeth occurs early and is easily overlooked. Parents should take extra precautions to protect their children’s dental health, cultivate brushing habits, and avoid excessive sweets, among other things. Irritability, low-grade fever and disturbed sleep may also occur during tooth replacement, and attention should be paid to timely consultation.