The Volumetric Changes of the Lips in Orthodontic Patients with Bonding or Debonding Labial Fixed Orthodontic Appliances

Abstract

Objective: The aim of this study was to evaluate volumetric change in the lips after placement or removal of labial fixed orthodontic appliances using three-dimensional (3D) surface scanning system. Materials and methods: Bonding group is composed of 30 patients who planned to start orthodontic treatment, and debonding group is another 30 patients who had been treated successfully with Class I normal occlusion and planned to remove the brackets. Three-dimensional facial scanning was performed before placement (T1), immediately after placement (T2) of the labial orthodontic appliances, and before removal (t1), immediately after removal (t2), 3 to 6 months after removal of the appliances (t3). The volumetric differences of the lips were calculated. Results: The volume of lips increased after bonding the brackets 502 mm3 in the upper lip and 534 mm3 in the lower lip on average. In debonding group, the volume in the upper and lower lips decreased 376 mm3 and 394 mm3 respectively immediately after debonding, and more decreased 513 mm3 and 431 mm3 for the 3-6 months of retention period on average. Comparison between volumetric changes during t1-t2 and t2-t3 showed no significant differences. In the comparison between bonding and debonding groups, the volumetric differences between T1 and T2 in bonding groups were not significantly different with those between t1 and t2 in debonding group, but significantly different with those between t1 and t3. Conclusion: The upper and lower lips were protruded immediately after bonding the brackets, and retruded immediately after debonding them. The lips were retruded more during the retention period.