Standard forms of dentition and mandible for applications in rotational panoramic radiography

Mathematical expressions describing the average form and size of the dentition and the mandible are presented. These expressions should be of value in applications of panoramic radiography when reference to an average standard jaw form is of interest. Data were collected from axial radiographs of 35 males and 35 females of three ethnic groups: Mexican-Americans, black Americans and American and Scandinavian Caucasians. Curves were traced on the axial radiographs representing the dentition and the mandible and points along these curves digitized. Mathematical expressions were established using advanced algorithms for orthogonal polynomial curve fitting, i.e. perpendicular distances to the curved dentition and mandible were minimized rather than distances parallel to the y-axis in an arbitrarily chosen coordinate system. The standard deviations around the polynomials defining the average curves are demonstrated and expressions for calculating the continuously varying standard deviations are given.