Longitudinal changes in the maxilla and the maxillary-mandibular relationship between 8 and 17 years of age.

The purpose of this study was to examine the changes in the maxilla and the maxillary-mandibular relationship as they relate to standing height, which is one indicator of skeletal maturation. The subjects for this study consisted of twenty males and fifteen females for whom cephalograms were taken annually between the ages of 8 and 17 years. Descriptive statistics summarized the changes in standing height and the facial parameters from 8 to 17 years of age. Analysis of variance was used to describe the linear and angular changes and also to compare the mean growth profiles of each of the facial parameters to the growth profile for standing height. Autocorrelation analysis was used to assess the predictability of the growth profiles of the facial parameters from the profile of standing height for the same person. Three periods of growth were also compared: premaximum, maximum, and postmaximum. The findings in the present investigation indicated that (1) the growth profile of the absolute and incremental changes in standing height and the various facial parameters were in general significantly different between males and females; (2) the growth profile of standing height was significantly different from the parameters describing maxillary length and relationship as well as maxillary-mandibular relationship; (3) the changes in maxillary length (A-Ptm) were significantly larger in the maximum period of growth than the other two periods of growth for both males and females; (4) the changes in maxillary relationship were significantly different in the maximum period of growth than in the other two periods of growth in males only; (5) the change in maxillary-mandibular relationship was not significantly different in the three periods of growth; (6) autocorrelation analysis revealed that the growth profile of the facial parameters could not be predicted from the growth profile of standing height of the same individual; that is, the growth profile of height was found to have little predictive value in determining the growth profile of any of the other parameters. The present findings as well as those of a previous investigation indicate that treatment of anteroposterior discrepancies should be initiated as soon as the orthodontist believes that treatment is indicated, rather than waiting for the pubertal "spurt," since the presence, magnitude, and timing of such events in any one patient are highly unpredictable, at least to the degree that renders them clinically useful to the orthodontist.