抄録
The purpose of this study was to evaluate the changes of soft tissue profile following anterior segmental maxillary osteotomy (ASMO) in mandibular retrognathia patients. A total of 20 patients were enrolled in this study. All the patients had undergone only ASMO to correct excess overjet due to skeletal discrepancy. The subjects were divided into two groups: mandibular retrognathia group (MR group: SNB < -1 S.D., 7 females and 3 males, mean age 24.4 years) and maxillary protrusion with no mandibular retrognathia group (NMR group: SNB > -1 S.D., 9 females and 1 male, mean age 24.6 years). Lateral cephalograms at first visit (T0) and just after active treatment (T1) were traced and superimposed. As for the x-y coordinate system, the x-axis parallel to the Frankfurt horizontal (FH) plane passing through the sella turcica was used as the horizontal reference. Linear and angular measurements were statistically evaluated between the changes of the hard and soft tissues in each group.
The following results were obtained:
The changes of all hard tissue measurement values were not significantly different between the two groups. In respect of soft tissue changes, protrusive upper and lower lip and retrusive chin were corrected in both groups. Namely, soft tissue landmarks in the subnasal, upper and lower lip, and chin regions were significantly moved backward in both groups. In addition, the landmarks in the mental region (SPog, SGn) were more significantly moved downward in the MR group than in the NMR group.
The present study suggests that a distinct skeletal pattern at the initial stage gives a different soft tissue profile in the mental region after surgery. The improvement of protrusive upper and lower lip and retrusive chin in both groups implies that ASMO is a useful technique for treating mandibular retrognathia patients.
