title: An extended period of functional appliance therapy: a controlled clinical trial comparing the Twin Block and Dynamax appliances.
abstract: The aim of this clinical trial was to compare the hard- and soft-tissue effects of 15 month full-time functional appliance therapy with Twin Block (TB) and Dynamax (Dx) appliances. The effects on both hard and soft tissue were analysed using cephalograms and three-dimensional optical surface laser scans. One hundred and three subjects with a class II division 1 malocclusion, and a minimum overjet of 7mm were available for analysis following stratified randomization according to gender and age. Data was collected at the start of treatment, 15 month therapy, and after 3 month post-treatment observation. Statistical analysis was conducted using analysis of covariance. The results demonstrated both appliances corrected the overjet with significantly increased skeletal dimensional changes with the TB compared with the Dx with forward movement of pogonion of 5.2mm (TB) and 0.7mm (Dx) P = 0.003. In addition, significant changes occurred particularly in the vertical dimension where there was also an increase in total anterior face height in both groups (TB = 6.4mm, Dx = 5.5mm) and significant (P = 0.003) mandibular length changes were also observed (TB = 7.2mm, Dx = 3.8mm). The cephalometric soft-tissue changes were significantly different between the two appliances at soft-tissue pogonion (TB = 9.8mm, Dx = 4.6mm, P = 0.001). Laser scan three-dimansional changes showed significant difference in the lower labial sulcus region where forward movements were observed (TB = 8.2mm, Dx = 6.2mm; P = 0.04). Overall these changes appear to be greater and more stable than those achieved in a previous 9 month study.
authors.affiliation: *Department of Orthodontics, Bart's & The London NHS Trust, London, r.t.lee@qmul.ac.uk.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Lee
authors.affiliation: *Department of Orthodontics, Bart's & The London NHS Trust, London.
authors.forename: Emma
authors.initials: E
authors.lastname: Barnes
authors.affiliation: **East Kent Hospitals University NHS Foundation Trust.
authors.forename: Andrew
authors.initials: A
authors.lastname: DiBiase
authors.affiliation: *Department of Orthodontics, Bart's & The London NHS Trust, London.
authors.forename: Ravichandram
authors.initials: R
authors.lastname: Govender
authors.affiliation: ***Department of Orthodontics, Q.M.U.L., London, UK.
authors.forename: Usman
authors.initials: U
authors.lastname: Qureshi
mesh_terms: D000293:Adolescent; D002508:Cephalometry / Q000379:methods; D002648:Child; D002680:Chin / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007834:Lasers; D008046:Lip / Q000473:pathology; D008297:Male; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D008334:Mandible / Q000473:pathology; D008437:Maxilla / Q000473:pathology; D009295:Nasal Bone / Q000473:pathology; D016382:Orthodontic Appliance Design; D017289:Orthodontic Appliances, Functional; D057887:Overbite / Q000628:therapy; D014716:Vertical Dimension