title: Treatment and posttreatment effects of quad-helix/crib therapy of dentoskeletal open bite.
abstract: OBJECTIVE
  To investigate the effects of the quad-helix/crib (Q-H/C) appliance in subjects with thumb-sucking habits and dentoskeletal open bite at 2 years after the end of active treatment.
  
  
  METHODS
  The records of 21 subjects treated with the Q-H/C appliance were compared with a control group of 21 untreated subjects with similar vertical relationships. Lateral cephalograms were obtained before treatment (T1; mean age 8.4 +/- 1.4 years) and at about 2 years after treatment (T2; mean age 11.7 +/- 1.9 years) and analyzed. Mean treatment duration was 1.5 years +/- 7 months. The T2-T1 changes in the two groups were compared with a nonparametric test for independent samples.
  
  
  RESULTS
  The mean increase in overbite during Q-H/C therapy (4.1 mm) represented an overcorrection of the amount of anterior open bite at T2. Both the maxillary and mandibular incisors showed significantly greater extrusion in the Q-H/C group than in the control group. The treated group showed a greater downward rotation (1.8 degrees ) of the palatal plane than did the control group. This change was associated with a clinically significant reduction in the palatal plane/mandibular plane angle (-2.5 degrees ) in the Q-H/C group. The upper lip showed significant retraction relative to the E-plane in the treated group (3.6 mm) compared with the controls.
  
  
  CONCLUSIONS
  The Q-H/C appliance was effective in correcting dental open bite in 85% of the growing subjects with thumb-sucking habits and dentoskeletal open bites. Correction of anterior open bite was associated with a clinically significant improvement in maxillomandibular vertical skeletal relationships.
authors.affiliation: Department of Orthodontics, The University of Rome Tor Vergata, Rome, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Cozza
authors.forename: Manuela
authors.initials: M
authors.lastname: Mucedero
authors.forename: Tiziano
authors.initials: T
authors.lastname: Baccetti
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Franchi
mesh_terms: D016022:Case-Control Studies; D002508:Cephalometry / Q000706:statistics & numerical data; D002648:Child; D005260:Female; D005386:Fingersucking / Q000009:adverse effects*; D006801:Humans; D008297:Male; D024343:Open Bite / Q000209:etiology / Q000628:therapy*; D009967:Orthodontic Appliances; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D014716:Vertical Dimension