title: Therapeutic effects of functional orthodontic appliances on cervical spine posture: a retrospective cephalometric study.
abstract: BACKGROUND
  Interactions between the cervical spine and the stomatognathic system have been discussed in literature. The present study was conducted to investigate whether, and to what extent, orthodontically induced mandibular advancement produces changes in cervical spine posture. Furthermore, possible appliance-specific effects should be distinguished.
  
  
  METHODS
  The cephalograms of 64 patients with skeletal class II were analysed before and after mandibular advancement. Linear and angular cephalometric parameters were identified to define the position of the atlanto-occipital and atlantoaxial joints. The total example was divided into two subgroups (comprising 32 individuals each) according to the employed appliance: activator versus bite-jump appliance (BJA). Student's t-test and analysis of covariance were used for statistical analysis.
  
  
  RESULTS
  Overall, a significant straightening of the cervical spine was observed during the treatment. This conclusion is based on changes of Chamberlain (p = 0.0055), CVT (p = 0.0003), OPT (p < 0.0001), Redlund-Johnell/Petersson (p < 0.0001), McGregor-mC2 (p = 0.0333) and AT-FH (p = 0.0445). Improvements in occipitoatlantal dislocation were also observed in the total sample. Appliance-specific changes were found in the activator subgroup for a number of linear parameters (Chamberlain, McGregor, CVT, OPT, Redlund-Johnell/Petersson). In contrast, only two linear parameters (OPT and Powers ratio) revealed statistically significant changes in the BJA subgroup.
  
  
  CONCLUSIONS
  During skeletal class II treatment the position of upper cervical spine changes. In the activator subgroup the observed effects were more pronounced than those in the BJA subgroup. Further studies including a control group comprised with non-treated class II patients are needed to assess whether these effects may be caused directly by the appliances irrespective of growth.
authors.forename: Maren
authors.initials: M
authors.lastname: Ohnmeiß
authors.forename: Gero
authors.initials: G
authors.lastname: Kinzinger
authors.forename: Julia
authors.initials: J
authors.lastname: Wesselbaum
authors.affiliation: Department of Orthodontics, University Hospital Giessen and Marburg, Georg-Voigt-Strasse 3, Marburg 35039, Germany. korbmacher@staff.uni-marburg.de.
authors.forename: Heike M
authors.initials: HM
authors.lastname: Korbmacher-Steiner
mesh_terms: D000293:Adolescent; D002508:Cephalometry; D002574:Cervical Vertebrae / Q000502:physiology*; D002648:Child; D006801:Humans; D008297:Male; D019186:Mandibular Advancement / Q000295:instrumentation; D017289:Orthodontic Appliances, Functional; D011187:Posture; D012189:Retrospective Studies