Under normal circumstances, the decrees appear symmetrically, with the same depth on both sides, but sometimes the decrees appear deep on one side and shallow on the other. There are many reasons for the formation of decree lines, such as excessive eating and chewing of unilateral teeth; Often make exaggerated expressions; I am used to sleeping on one side for a long time when I sleep; I like to use pillows that are too soft and so on. Of course, there are also typical skin tissues caused by relaxation and aging, one side is deep and the other side is shallow.