The main objective of this study was to find a predictive multivariate model of jaw development in patients with the most frequent cleft malformation, i.e. complete unilateral cleft lip and palate (UCLP). The prediction is urgently needed from the clinical aspect. It will be possible to detect early adversely developing patients upon whom intensive care and adequate orthodontic treatment could be devoted in good time. The study is based on a long-term cephalometric follow-up of lateral X-rays of 48 boys with UCLP during puberty. Using multivariate methods we investigated the relationship of 75 craniofacial characteristics of size, shape and position during the time interval from 10 to 15 years of age. As the prediction of the development of the jaws in patients with clefts is very complicated, we have attempted to find a reliable predictive system. Sagittal intermaxillary relations can be predicted most accurately in the investigated group by means of the angular dimension Ss-N-Sm (A-N-B angle). We suggest using in clinical practice trinomial equations, the coefficient of determination of which varies round 0.80, and thus the position of the variables can be explained with sufficient accuracy (the coefficient of determination 0.64 is considered in orthodontics a value of predictive significance). The proposed predictive technique was successfully tested in a group of 12 patients with the same diagnosis and therapy.

        Key words: X-ray cephalometry, longitudinal study, complete unilateral cleft lip and palate, jaw relations, puberty, multiple regression, prediction