Positional stability following intentional posterior ostectomy of the distal segment in bilateral sagittal split ramus osteotomy for correction of mandibular prognathism.

PURPOSE: In order to minimize post-operative relapse after mandibular setback using bilateral sagittal split ramus osteotomy, we have recently tried a technique, i.e. intentional ostectomy of the posterior part of the distal segment. The aim of this study was to evaluate the effects of this technique on the frequencies and extent of post-operative relapse.

PATIENTS: This study was based on 61 cases of mandibular prognathism. The traditional sagittal split was performed in 24 cases (average age: 22.0+/-3.8) as a control group and the technique of additional distal ostectomy was used in the other 37 cases (average age: 23.2+/-3.2) as a test group.

METHODS

Horizontal and vertical changes in the position of the body of the mandible were measured to determine the amount of long-term post-operative relapse. The amount of relapse was compared between groups and the statistical significance of the differences was evaluated.

RESULTS

The relapse index of the test group was significantly lower than that of the control group in the 6- and 12-month post-operative periods (p>0.005). The horizontal relapse index and facial length relapse index of the test group were lower than those of the control group 12 months post-operatively (p<0.05).

CONCLUSION

This method should be considered as a useful method to maximise long-term post-operative stability.