Abstract
We made periodical observations, during the deciduous dentition, of occlusions in 29 Japanese girls with deciduous reversed bite in order to find out what morphological characteristics the self corrected cases had.
Our previous study showed that there were self corrected (N: 13) and the non-self corrected (R: 16) groups.
The purpose of this study was to determine whether the difference between the N and R Groups occured as morphological differences at their initial visit or a result of occlusal changes.
The materials used in this study were the serial lateral cephalograms of 29Japanese girls. Angular and dimensional analyses were performed.
The following results were obtained:
1. Characteristics in the initial examination of both groups: The ptm'-ms and porion location in the R Group were significantly larger than those in the N Group. The lower facial height in the N Group was greater than that in the R Group. Other measurements did not show any significant differences between the groups.
2. Longitudinal changes in the N Group: The mean changes of this group showed clockwise rotation of the mandible caused by a decrease in SNB and SNP, and an increase in the SN-Gn and Ramus (SN) angles respectively as a skeletal pattern. Dental change caused an increase in the UA-SN angle and a decrease in the LA-MP. angle; The maxillary deciduous central incisors tipped labially and the mandibular deciduous centra incisors tipped lingually. Individual changes showed three patterns; (a) an improvement of the skeletal pattern, (b) clockwise rotation of the mandible and (c) axial changes of the maxillary and mandibular deciduous central incisors. The self corrected groups showed a combination of these changes.
3. Longitudinal changes of the R Group: The mean changes of this group showed an increase in the SN-Gn and Ramus (SN) angles. As to individual changes, some of the R Group cases showed a tendency toward improvement in some measurements which were also shown in the N Group, although many cases in the R Group showed changes toward a worsening of the intermaxillary relationship. Moreover, most cases in these changes showed a single pattern of the (a), (b) or (c).
