A new method to determine tooth positions and dental arch dimensions.

Dental arch width dimensions have been measured by use of certain cusp tips (MOORREES, The Dentition of the Growing Child, 1959) or points at the lingual cervical margin of the teeth (BAUME, J Dent Res 29:123, 1950) as reference points. However, cusp tips wear off, vary in number and location, and do not allow adequate transformation from the deciduous canines and molars to their successors (Fig 1). Points at the lingual cervical margin are affected by the buccolingual width of a tooth and its eruption level. Recent technical developments involve computer graphic techniques in handling dental cast information as recorded by occlusal photographs (BIGGERSTAFF, Angle Orthodont 40:28, 1970) and the direct collection of numerical data from dental casts in a two dimensional (SAVARA and SANIN, Am J Phys Anthropol 30: 315, 1969) or three dimensional way (VAN DER LINDEN, IADR Program and Abstracts of Papers, No. 286, 1970). With both approaches the construction of more appropriate reference points can be realized. Reference points to determine tooth position and dental arch dimensions should represent the real position, the "center" of the crown, and be independent of number of cusps, location of cusps, abrasion, and eruption level.