Prediction of mandibular growth in Japanese children age 4 to 9 years.

PURPOSE The purpose of this study was to propose mathematical models for predicting mandibular growth direction and amount in children with normal skeletal relationship from 4 to 9 years of age using the craniofacial characteristics found on the head films. METHODS Lateral cephalograms of 27 Japanese children with normal occlusion at 4 (T1) and 9 (T2) years of age were traced and measured. Fifteen linear and angular measurements were performed. The angle NSGn and the distance S-Gn were used to represent the growth direction of the mandible and its growth amount, respectively. The data were analyzed by multiple linear regression analysis. RESULTS The multiple regression analysis revealed 2 models for the mandibular growth prediction. The equation (model) for the mandibular growth direction is YD=-39.844+1.206 X1 +0.333 X2, where YD is the predicted value of the angle NSGn at T2. X1 is the value of the angle NSGn at T1 and X2 is the value of the angle SNB at T1 (R2=0.719, P<0.05). The equation for the mandibular growth amount is YA=99.052+0.782 X3-0.517 X4, where YA is the predicted value of the distance S-Gn at T2. X3 is the distance S-Gn at T1 andX4is the angle NSAr at T1 (R2=0.610, P< 0.05). CONCLUSIONS The direction of the mandibular growth at 9 years of age can be predicted by 72% with the regression equation using the angles NSGn and SNB at 4 years of age. The amount of growth of the mandible can be predicted by 62% by using the distance S-Gn and the angle NSAr at 4 years old. The model for the growth amount provides a relatively lower predictive value than that of the growth direction.