To easily and efficiently design various kinds of dental prosthetic appliances by designing dental prosthetic appliance models of crowns, bridges, etc., by using pontic models corresponding to various tooth shapes.
The pontic models Pm stored in the data base of a computer are expressed by combining patches (p(1), p(2),...p(n), p(n+1),...) formed by, for example, segmenting the models to many rectangular curved surface shapes. The data indicating the three-dimensional curved surface shapes of the respective patches p(n) and the constitution positions (three-dimensional positions) of the respective patches are preserved as shape expression data into the data base. The dental prosthetic appliance models, such as crowns and bridges, are designed by using such pontic models and, therefore, only the data indicating the pontic shapes are needed for each of the respective teeth as the data base and the data base is diminished. The management thereof is simple and the efficient design is made possible.