This study was performed to obtain the predictable ratio of post-operative soft tissue changes of the midfacial measurement values following maxillary movement according to various type of Le Fort-Ⅰosteotomy for orthognathic purposes.
Fifty patients(36 males and 14 females) of Koreans who had undergone surgical alterations of the maxilla were selected and classified into four groups depending upon the type of maxillary movements by means of the Le Fort-Ⅰosteotomy : group
Ⅰ(13
patients)was moved by posterior impaction, Group Ⅱ(18 patients) was moved by posterior impaction and advancement simultaneously, Group Ⅲ(9 patients) was moved by advancement only, and Group Ⅳ(10 patients) was moved by superior repositioning
both
anteriorly and posteriorly. Post-operative changes of the soft tissue measurements according to changes of the hard tissue measurements were examined on pre- and post-operative cephalometrics ad the ratio of changes were analyzed.
@ES The results obtained were as follows:
@EN 1. Soft tissue measures were closely correlated to changes of the maxillary skeleton in the horizontal plane, but soft tissue measures in the vertical plane did not correlate to maxillary movement.
2. In the posterior impaction type, the predictable ratio of the Pn was 30% of the ANS, the Cm was 40% of the ANS, the Sn was 50% of the ANS, the Ls was 40% of the Pr, and the Stm was 60% of the I in the horizontal plane.
3. In the posterior impaction and advancement type, the predictable ratio of the Pn was 45% of mean of the ANS and A, the Cm was 55% of mean of the ANS and A, the Sn was 65% of mean of the ANS and A, the Ls was 60% of mean of the A and I, the Stm
was
70% of the I in the horizontal plane.
4. In the advancement type only, the predictable ratio of the Pn was 50% of the A, the Stm was 20% of the Pr in the horizontal plane. the ratio of changes in the Sn was 60% of the ANS, but there was no statistically significant difference.
5. In the superior repositioning type, all ratios of soft tissue changes were not predictable.
6. All ratios of changes in the thickness, length and area of upper lip, following maxillary movement, was largest in group II, however, the magnitude of this ratio was so little that there was no clinical significance.
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