Gum chewing exercise is effective to increase MBF and a* values of preschool children and the effects are maintained after exercise completion.

The purpose of this study was to propose mathematical models for predicting mandibular growth direction and amount in children with anterior crossbite from 4 to 9 years of age using lateral cephalograms. Lateral cephalograms of 25 Japanese children with anterior crossbite at 4 years (T1) and 9 years (T2) were traced and measured. The measurements were performed on 18 angular and 13 linear measurements. Variation of the angle NSGn and the distance S-Gn were used to represent the variation of growth direction and amount, respectively. The data were analyzed statistically by multiple regression analysis. The analysis revealed 2 models for the prediction of the mandibular growth. The variation of the direction of mandibular growth can be predicted by 68% with the regression equation using the angles NSAr, Nasal floor to SN and SNA at T1. The variation of the amount of mandibular growth can be predicted by 69% with the regression equation using the distance Ar-Me, the angles Nasal floor to SN, NSBa and Interincisal angle at T1. The parameters for the mandibular growth prediction for crossbite children are different from those of children with normal occlusion. This study will be of great importance to predict future mandibular growth of children with anterior crossbite.dinally on the serial lateral cephalograms [1][2][3] . Many methods for mandibular growth prediction have been proposed for clinical use by using different cephalometric measurements [4][5][6][7][8][9] .Most of the previous studies of mandibular growth prediction were focused on studying children at the age of the mixed-dentition period after receiving orthodontic treatment 10) , so there were few studies intending for children with the deciduous-dentition. Most of the previous studies of prediction for children with anterior crossbite emphasized whether orthodontic treatment could succeed 11) .The purpose of this study was to propose mathematical models by using the craniofacial characteristics found on the lateral cephalograms for predicting mandibular growth direction and amount in children with anterior crossbite from 4 to 9 years of age using lateral cephalograms.