title: Treatment effects of quad-helix on the eruption pattern of maxillary second molars.
abstract: OBJECTIVE
  To evaluate the effects of quad-helix treatment on the eruption pattern of maxillary second molars in patients with maxillary incisor crowding.
  
  
  METHODS
  The lateral cephalograms of 40 consecutively treated patients in the early mixed-dentition group (treatment group) were examined in comparison with those of the same number of untreated patients with a similar form of malocclusion (control group). The cephalograms of the treated patients were taken at the start (T0) and at the end (T1) of treatment, and those of the untreated patients were also taken at about the same time as T0 and T1. The mean ages at T0 and T1 in the two groups were about the same.
  
  
  RESULTS
  Distal tipping and movement and impeded extrusion of the maxillary first molars were notable in the treatment group compared with the control group. The actual treatment changes with the use of the quad-helix found expression in distal tipping and impeded vertical eruption of maxillary second molars. The more the maxillary first molars were tipped distally and the less the maxillary first molars extruded, the more the vertical eruption of the maxillary second molars was impeded.
  
  
  CONCLUSIONS
  Quad-helix treatment gives rise to spontaneous distal tipping and impeded vertical eruption of the maxillary second molars.
authors.affiliation: Nippon Dental University Niigata Hospital, Niigata, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Isao
authors.initials: I
authors.lastname: Shundo
authors.forename: Toshiya
authors.initials: T
authors.lastname: Endo
mesh_terms: D000704:Analysis of Variance; D016022:Case-Control Studies; D002508:Cephalometry; D002648:Child; D003818:Dentition, Mixed; D005260:Female; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology*; D008297:Male; D008310:Malocclusion / Q000628:therapy*; D008437:Maxilla / Q000254:growth & development*; D008963:Molar / Q000254:growth & development*; D009967:Orthodontic Appliances / Q000009:adverse effects*; D014078:Tooth Eruption / Q000502:physiology*; D014087:Tooth Movement Techniques / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods