Prediction of mandibular growth potential between 10-14 years of age

Objectives: It has been suggested that patients’ future mandibular growth can be predicted from their existing morphology. The purpose of this cephalometric study was to determine whether published arborization methods can be used to predict differences in the amount of mandibular growth and rotation. Methods: The sample included 203 untreated subjects (48.3% female) with longitudinal cephalograms at 10 and 14 years of age. Tracings of the mandible were superimposed on stable natural reference structures to quantify true mandibular rotation. Arborization was based on 1) the ANB angle and 2) 192-(2*SNB)-MPA. Results: Compared with females, males showed significantly (p<0.01) greater increases in Co-Pg (9.4 vs 8.1 mm), greater true forward rotation (2.9 vs 1.7 deg), and increases (0.3 deg) rather than decreases (0.7 deg) in the SNB angle. The MPA decreased significantly (0.8 deg) with no apparent sex differences. Of the 10 year old measures evaluated, only Co-Pg showed a significant (p=.008), albeit low (R=.20) correlation with changes in Pg-Co between 10-14 years. There were no significant differences in growth changes of Co-Pg between groupings defined by the two-tier arborization. There were significant differences (p=.016) between groups in the amounts of true rotation, but differences did not appear to be due to the group's predicted growth potential. Conclusions: There is no correspondence between individuals’ growth potential and their morphologically based typology. Predictions of growth potential based on static assessments are not reliable enough to be clinically useful.