Cephalometric changes during self-correction of primary anterior crossbite

Longitudinal growth changes were investigated cephalometrically for sixty-one Japanese girls who had anterior crossbite at the initial visit (ages 3 years and 11 months on an average). Cephalograms were taken annually from the initial visit to the end of the observation period (ages 7 years 6 months on an average). Eleven of them (Group N1) showed self-correction of anterior crossbite during the primary dentition; ten (Group N2) showed self-correction when the permanent incisors erupted and forty (Group R) did not show self-correction. There was no statistical skeletal difference between Groups N1 and N2 during the observation period. Groups N1 and N2 were larger, however, than Group R in A'-Ptm'/Pog'-Go (p < 0.05) and Group N1 was smaller than Group R in Pog'-Go/N-S (p < 0.01) at the end of the observation period. In summary, favorable growth of the maxilla relative to the mandible leads to self-correction of primary crossbite and when mandible size relative to the cranial base is large, primary crossbite does not show self-correction.