Mandibular setback osteotomy: facial soft tissue behavior and possibility to improve the accuracy of the soft tissue profile prediction with the use of a computerized cephalometric program: Quick Ceph Image Pro: v. 2.5.
OBJECTIVE
In part I, to derive ratios of soft to hard tissue profile changes after mandibular setback surgery and to report postoperative changes in soft tissue thickness at the lip and chin areas and, furthermore, to test the hypothesis that soft tissue thickness can act as one of the predictors of soft tissue response after surgery. In part II, to compare the predicted profile lines, using either the customized or the pre-programmed ratios, with the actual postsurgical outcomes.


METHODS
A retrospective study with the sample divided into two groups for different purposes.


METHODS
Department of Orthodontics and Department of Oral and Maxillofacial Surgery at Göteborg University, Sweden. Forty-one Caucasian subjects in need of mandibular setback surgery only.


METHODS
Hard and soft tissue movements and changes in soft tissue thickness after surgery were calculated using a customized analysis. Comparisons of the predicted profile outcomes with the actual postsurgical outcomes were carried out with another customized analysis.


METHODS
Distance measurements of certain landmarks in relation to constructed reference lines, both in horizontal and vertical planes, were calculated.


RESULTS
The upper lip thickness decreased and the lower lip thickness increased after surgery. The hypothesis that the soft tissue thickness at the lip and chin areas could act as predictors of the ratios of soft to hard tissue changes after surgery, was not supported. Ratios for the lower lip of about 83% of the horizontal and 14% of the vertical movement of the PM point on the bony chin were found in Part I. In Part II, these ratios were introduced and the predicted profile moved significantly closer to the actual postsurgical outcome than if using the pre-programmed ratios (p < 0.05).


CONCLUSIONS
Being able to customize the ratios of soft to hard tissue changes after a particular type of orthognathic surgery will enhance the accuracy of a patient's predicted profile outcome. These ratios should be pre-programmed in future versions of the software.
Chunmaneechote
P
P
Department of Orthodontics, Faculty of Odontology, Göteborg University, Sweden.
Friede
H
H
D000293:Adolescent; D000328:Adult; D002508:Cephalometry / Q000379:methods*; D002680:Chin; D005145:Face / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008046:Lip; D008297:Male; D008334:Mandible / Q000601:surgery*; D010027:Osteotomy / Q000379:methods*; D011237:Predictive Value of Tests; D011378:Prognathism / Q000601:surgery; D012044:Regression Analysis; D012189:Retrospective Studies; D012886:Skull / Q000033:anatomy & histology; D012984:Software; D014716:Vertical Dimension