title: Response of the maxillary dentition to a statically determinate one-couple system with tip-back mechanics: A prospective clinical trial.
abstract: OBJECTIVE
  To quantify the effects of tip-back mechanics on the maxillary first molars and incisors.
  
  
  METHODS
  Sixteen subjects with Class II end-on malocclusion were treated with an intrusion arch to achieve distalization of the maxillary molar through tip-back mechanics. Lateral cephalograms were taken prior to molar tip-back (T1), after molar tip-back (T2), and after molar root uprighting (T3). Data were analyzed using the Friedman's and Wilcoxon signed rank tests to evaluate differences in time points (P ≤ .016).
  
  
  RESULTS
  The maxillary first molar distalized 1.53 mm (P = .001) with 6.65° (P = .001) of distal tipping and 0.86 mm (P = .001) of extrusion at T2. Minor relapse of the first molar (mesial direction) was seen at T3. The maxillary incisors flared labially 0.4 mm, and the incisor root apex moved palatally 1.19 mm (P = .005) at T2. At T3, the incisor root apex moved palatally 1.5 mm (P = .003) from T1. An angular change from T1 of 3.31° (P = .008) and 3.53° (P = .014) was seen at T2 and T3, respectively, as a result of palatal root movement of the maxillary incisors.
  
  
  CONCLUSIONS
  A significant amount of distalization of maxillary molars was attained at the crown level with tip-back mechanics. Palatal root angulation change was significant in the incisors with minimal anteroposterior movement of the incisal edge.
authors.affiliation: a  Clinical Assistant Professor, Division of Orthodontics, University of Connecticut, School of Dental Medicine, Farmington, Conn.
authors.forename: Nandakumar
authors.initials: N
authors.lastname: Janakiraman
authors.affiliation: b  Tulare, Calif.
authors.forename: Pawandeep
authors.initials: P
authors.lastname: Gill
authors.affiliation: c  Assistant Professor, Director Orthodontic Fellowship Program, Division of Orthodontics, University of Connecticut, School of Dental Medicine, Farmington, Conn.
authors.forename: Madhur
authors.initials: M
authors.lastname: Upadhyay
authors.affiliation: d  Professor and Head, Department of Craniofacial Sciences, Alumni Endowed Chair, School of Dental Medicine, University of Connecticut, Farmington, Conn.
authors.forename: Ravindra
authors.initials: R
authors.lastname: Nanda
authors.affiliation: e  Associate Professor, Graduate Program Director, Charles Burstone Professor, Division of Orthodontics, University of Connecticut, School of Dental Medicine, Farmington, Conn.
authors.forename: Flavio
authors.initials: F
authors.lastname: Uribe
mesh_terms: D002508:Cephalometry; D003817:Dentition; D006801:Humans; D007180:Incisor; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D008437:Maxilla; D008963:Molar; D011446:Prospective Studies; D014087:Tooth Movement Techniques
keywords: 1 couple force system; Distalization; Intrusion arch; Tip-back mechanics