title: Treatment timing for an orthopedic approach to patients with increased vertical dimension.
abstract: BACKGROUND
  The aim of this study was to investigate the role of treatment timing on the effectiveness of vertical-pull chincup (V-PCC) therapy in conjunction with a bonded rapid maxillary expander (RME) in growing subjects with mild-to-severe hyperdivergent facial patterns.
  
  
  METHODS
  The records of 39 subjects treated with a bonded RME combined with a V-PCC were compared with 29 untreated subjects with similar vertical skeletal disharmonies. Lateral cephalograms were analyzed before (T1) and after treatment or observation (T2). Both the treated and the untreated samples were divided into prepubertal and pubertal groups on the basis of cervical vertebral maturation (prepubertal treated group, 21 subjects; pubertal treated group, 18 subjects; prepubertal control group, 15 subjects; pubertal control group, 14 subjects). Mean change differences from T2 to T1 were compared in the 2 prepubertal and the 2 pubertal groups with independent-sample t tests.
  
  
  RESULTS
  No statistically significant differences between the 2 prepubertal groups were found for any cephalometric skeletal measures from T1 to T2. When compared with the untreated pubertal sample, the group treated with the RME and V-PCC at puberty showed a statistically significant reduction in the inclination of the mandibular plane to the Frankfort horizontal (-2.2 mm), a statistically significant reduction in the inclination of the condylar axis to the mandibular plane (-2.2 degrees), and statistically significant supplementary growth of the mandibular ramus (1.7 mm).
  
  
  CONCLUSIONS
  Treatment of increased vertical dimension with the RME and V-PCC protocol appears to produce better results during the pubertal growth spurt than before puberty, although the absolute amount of correction in the vertical skeletal parameters is limited.
authors.affiliation: Department of Orthodontics, University of Florence, Florence, Italy. t.baccetti@odonto.unifi.it
authors.forename: Tiziano
authors.initials: T
authors.lastname: Baccetti
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Franchi
authors.forename: Scott O
authors.initials: SO
authors.lastname: Schulz
authors.forename: James A
authors.initials: JA
authors.lastname: McNamara
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002508:Cephalometry / Q000706:statistics & numerical data; D002648:Child; D002680:Chin; D005115:Extraoral Traction Appliances; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000254:growth & development*; D024343:Open Bite / Q000628:therapy*; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D011627:Puberty; D012189:Retrospective Studies; D014716:Vertical Dimension