Assessment of soft-tissue vs hard-tissue changes after isolated functional genioplasty

Abstract

This study aimed to determine the vertical and horizontal soft-tissue vs hard-tissue changes after isolated functional genioplasty and to revisit hard-tissue remodeling at the symphysis. Seventy-five patients who underwent genioplasty as an isolated procedure at the end of their orthodontic treatment were divided into 3 groups on the basis of their age at surgery:<15 years (group 1), 15-18 years (group 2), and ≥19 years (group 3). Patients were evaluated at 3 time points: immediately before surgery (T1), immediately after surgery (T2), and 2 years after surgery (T3). In addition, 25 patients who did not accept genioplasty, were age-matched with group 1, and had a follow-up radiograph 2 years after the end of their orthodontic treatment were used as a control group. From T2 to T3, group 1 showed less forward horizontal hard-tissue and soft-tissue changes at pogonion (Pg) than the control group; however, no difference was noted for vertical changes at Me & Me'. From T1 to T3, the horizontal hard-tissue and soft-tissue changes at Pg were 6.39 mm and 6.72 mm, respectively, for surgical groups. Vertical hard-tissue change at menton (Me) showed a reduction of 1.63 mm (95% confidence interval [CI], -3.37 to 0.11) and 3.89 mm (95% CI, -5.83 to -1.95) in nongrowing female and male patients, respectively. The vertical soft-tissue change reduction was similar for nongrowing male and female patients (1.7 mm [95% CI, -2.96 to -0.45]). Soft-tissue thickness change at Pg (0.33 mm) was not significant. In contrast, a small but significant increase in soft-tissue thickness was noted at Me (0.54 mm). Linear regressions were calculated for all groups and allowed for predicting long-term soft-tissue changes (T3-T1) using the amount of surgical displacement (T2-T1). The horizontal hard-tissue change was stable for nongrowing patients, and the horizontal soft-tissue change was 92% of hard-tissue. Vertical soft-tissue change is less predictable. Variation of soft-tissue thickness after genioplasty can be explained by skeletal changes and the achievement of an unforced labial occlusion. These results support the functional and esthetic benefits of this surgery. Comparison with the control group showed that genioplasty does not change the growth pattern, and bone remodeling is likely to explain the difference noted at Pg.