Longitudinal craniofacial changes in Japanese adults with untreated maxillary and mandibular protrusions

This study evaluates the craniofacial change during the third decade of life and compared the changes that occurred in subjects with normal occlusion and untreated malocclusions. 10 cases each of normal occlusion, untreated maxillary protrusion and mandibular protrusion were subjected to cephalometric analysis and model analysis. The mean age at the beginning of the observation (T1) was 24 years, and the observation period (T2) was approximately 13 years in three groups. There was no significant difference in any cephalometric values between T1 and T2 in the normal occlusion group. The SNB angle was slightly decreased, the Y-axis was increased, and upper incisors were lingually inclined in the maxillary protrusion group and increasing of overjet and decreasing of overbite was observed in the mandibular protrusion group. In model analysis, the arch length discrepancy (ALD) and the inter-molar width (IMW) were slightly increased in the lower arch in the normal occlusion group and the upper arch length (AL) had decreased in the mandibular protrusion group. In conclusion, significant differences were found in the changes of several skeletal and dental parameters between normal occlusion and untreated malocclusion subjects in the third decade of life. These changes in the third decade of life should be considered in order to plan the orthodontic treatment and evaluate the long-term stability in the patients with maxillary and mandibular protrusion.