0 rthodontics as a specialty has advanced greatly since its inception in the early 1900’s. Case analysis or diagnosis has been and always will be a major factor in determining the success of orthodontic therapy. In the past dental casts and facial photographs of the patient afforded the primary diagnostic criteria. One dramatic step fvrward was afforded to orthodontics in the 1930’s by the work of Broadbent in ccphalomctric rocntgenography. Many volumes have been written and uncountable hours of research have been performed on this subject alone. Growth studies of vast, proportion have been accomplished, making possible the advent of computerized growth analysis for t,he clinician. Cephalometric roentgenography has become a routine diagnostic procedure taught throughout the specialty, in orthodontic graduate schools, and even ill oral surgery departments for the diagnosis of orthognathic surgical cdascs. Its accuracy and reproducibility go unquestioned : in fact, research attests to the “trueness” of cephalometric roentgenography. Today, the ccphalometric rocntgclrogram plus dental casts and photographs of the patient stand, generally, unquest,ionctl as the proper criteria for orthodontic diagnosis. These orthodontic records do indeed contain a vast amount of information, but n-hat do these diagnostic tools tell us concerning the relationship of the mandible to the maxilla? Is this actuall)a “true” occlusal relationship? Could there b’c a more meaningful way to achieve the information necessary to make an accurate orthodontic and functional diagnosis and yet remain clinically applicable ? Thompsonzo concluded that, “if fun&ion could be mcasurcd on records such as casts, photographs, and ccphalometric radiographs, a more realistic attitude toward function and a greater fear of the ravages of abnormal function would exist in the mind of the orthodontic profession. This in turn would promote greater respect from the general dental profession who set our cases many years after treat,ment and wonder if it has been at all worthwhile. All detrimental changes in a dentition are not the result of orthodontic treatment nor the failure of the orthodontist to recognize abnormal function. . . The point here is that