Soft tissue changes: a comparison between changes caused by the construction bite and by successful treatment with a modified Twin-block appliance

• Published in: European journal of orthodontics 2018-09, Vol.40 (5), p.512-518
• Main Authors: Salloum, Erfan, Millett, Declan T, Kelly, Niamh, McIntyre, Grant T, Cronin, Michael S
• Format: Article
• Language: English
• Subjects: Adolescent; Anatomic Landmarks - pathology; Cephalometry - methods; Child; Chin - pathology; Dental Occlusion; Dentistry; Face - pathology; Female; Humans; Imaging, Three-Dimensional; Lip - pathology; Male; Malocclusion, Angle Class II - pathology; Malocclusion, Angle Class II - therapy; Orthodontic Appliance Design; Orthodontic Appliances, Functional; Orthodontics, Corrective - instrumentation; Orthodontics, Corrective - methods
• ISSN: 0141-5387; 1460-2210
• DOI: 10.1093/ejo/cjx098

Summary Background/objectives Functional appliances are commonly used to correct Class II malocclusion. This study aimed to compare the facial soft tissue changes in Caucasians between pre-treatment and with the construction bite versus pre-treatment and completion of treatment with a modified Twin-block appliance (MTBA). Materials and methods Fifty-eight Caucasian subjects with Class II division 1 malocclusion had 3D stereophotogrammetric images captured pre-treatment (T1), with the construction bite (T2), and on completion of MTBA treatment (T3). Twenty-six landmarks were located on each image and 10% were re-landmarked 1 month later. Soft-tissue linear and volumetric changes (T1–T2 and T1–T3) were analyzed using linear mixed effect models (SAS® Version 9.4, www.sas.com). Results Forty-seven subjects [mean age 13.2 (SD 1.7) years] completed treatment [mean duration 9.8 (SD 3.8) months]. Differences between the changes from T1 to T2 versus T1 to T3 for upper facial and upper lip landmarks were insignificant (all P > 0.05) except for nasion, orbitale right, pronasale, and subnasale. For the same comparisons, lower lip and chin landmarks changed significantly (all P < 0.05) as did facial soft tissue volume (P< 0.0001). Limitations There was no control group. Conclusion The facial soft tissue changes from pre-treatment to with the construction bite were considerably more than those from pre-treatment to completion of treatment with a MTBA. Implication With MTBA treatment, the soft tissue changes from pre-treatment to with the construction bite in situ, overestimate those from pre- to post-treatment.