Abstract
To clarify the difference in growth change of the craniofacial size between normal occlusion and malocclusion, the authors analyzed the linear and square measurements of longitudinal lateral cephalograms at 6,9,12 and 16 years old boys, the same material as in the first report at the Burlington Growth Center in University of Toronto. We prescribed over 85° in SNA and less than 5° in SNB as bimaxillary protrusion, over 85° in SNA and over 5° in SNB as maxillary protrusion, and less than 85° in SNA and over 5° in SNB as mandibular retrusionn, and less than 85° in SNA and less than 5° in SNB as normal occlusion at 16 years old. The results were as follows.
1) The mean values of the over jet in the maxillary protrusion group were significantly larger than those in the normal occlusion group at ages 6 and 16.
2) The mean values of the over bite in the mandibular retrusion group were significantly larger than those in the normal occlusion group at age 6, which showed a larger tendency to disappear with age. During ages 6 to 16, the mean values of the over bite in the bimaxillary protrusion group showed a smaller tendency compared with the other groups.
3) The mean values of N-ANS and ANS-Me tended to be larger in the mandibular retrusion group at ages 6 to 16, which were significantly smaller than those in the normal occlusion group at ages 9 and 12.
5) The mean values of PNS-ANS in the maxillary protrusion group at each age were not found to show significant differences among the four groups.
6) The mean values of PNS-A in the maxillary protrusion group were significantly larger than in the normal occlusion group at ages 12 and 16, which were not shown at ages 6 and 9.
7) The mean values of G-Me in the four groups were almost the same at ages 6to 16.
8) The mean values of the maxillary contents in the maxillary protrusion group were not larger compared with the other groups, and those of mandibular retrusion group tended to be large among the four groups.
