Facial growth prediction: A comparison of methodologies

Introduction: The purpose of this study was to compare 3 methodologies that predict facial growth relative to incremental and positional changes over short- and long-term time periods. The 3 prediction systems that were tested and compared were the Ricketts analysis, the Johnston grid analysis, and the Fishman maturational analysis. Methods: Serial lateral cephalometric headfilms and hand-wrist films of 50 untreated subjects from the Burlington Growth Center at the University of Toronto, Toronto, Ontario, Canada, were used. The sample was subdivided by skeletal classification and further subdivided by sex. The sample comprised 19 skeletal Class I subjects (10 female, 9 male), 20 Class II subjects (10 female, 10 male), and 11 Class III subjects (6 female, 5 male). Three serial headplates were traced on each subject, and the associated chronologic and maturational ages were noted. The subjects were divided into a young adolescent subgroup approximately 9 years of age (T1), a midadolescent subgroup approximately 13 years of age (T2), and a late adolescent-adult age group approximately 20 years of age (T3). Predictions were made between the time periods. To measure and compare the predicted amounts of downward and forward skeletal growth vs the actual growth values, anatomic landmarks were chosen in the cranial base and on the maxilla and the mandible (Point A and gnathion), and increases between the respective points were measured. A paired t test was applied to each test group for the statistical analysis. Graphic representations were also created in the form of “positional envelopes” that encapsulated the predictive data for each methodology. To evaluate both incremental and positional accuracy, these data envelopes were subsequently related to the true positions of Point A and gnathion. Results and Conclusions: Although not the case in every instance, it was demonstrated that the maturationally oriented Fishman analysis was superior to both the chronologically based Johnston grid and Ricketts analysis for short- and long-term predictions.