Predicting the course of treatment for the individual case on the basis of traditional, morphological diagnostic records only, is at best uncertain. Current literature and clinical observations indicate that genetics and the individual's potential of adapting oro-facial functions to morphological changes play a crucial role. The problem of predictability obviously is multifactorial, and should be studied accordingly. In part 1 of this study, based on conventional documentation of two treated cases, the inadequacy of traditional diagnostic documentation limited to morphology and the subsequent uncertainty of predictions based thereon are demonstrated and discussed.