Human dental arches are very various in their sizes and dimensions as well as forms, so, it is very difficult to describe the shape of human dental arches as a criterion, and, further, to construct the preformed arch wires fit to them. In this study for solving these problems, the shape of elghty Korean normal lower dental arches were studied, and nine theoretical two-parameter catenary curves were derived, which were representative of all of the sample. Test were conducted which demonstrated that these nine cattenary curves would correspond with reasonable degree of accuracy to all of the dental arches, lower and upper.