The sixth age tooth, also known as the sixth age tooth, is a tooth that begins to erupt at the end of the dental row when the child is 6 years old, and is professionally called the first molar. Since this tooth does not replace any of the milk teeth when it erupts, many parents treat it as a milk tooth, but in fact it is a permanent tooth that will stay with the child for life, and is often the first batch or the first permanent tooth to begin to erupt. It erupts early because it does not replace the corresponding milk tooth itself and there is no resistance. For the sixth age teeth, once the eruption is finished, it is recommended to go to the professional dentistry department for the sulcus closure of the sixth age teeth, the sulcus closure can close the sulcus gap on the sixth age teeth, and prevent the occurrence of the sixth age teeth caries as much as possible.