title: Class II correction improves nocturnal breathing in adolescents.
abstract: OBJECTIVE
  To examine modifications in sleep pattern and in craniofacial morphology of adolescents with mandibular retrognathism.
  
  
  METHODS
  Sixteen subjects at maximum pubertal growth (12.6 years [±11.5 months]) were selected and treated for 12 months with maxillary expansion and mandibular advancement with a Herbst appliance. Cephalometric radiography and magnetic resonance imaging were obtained prior to and after treatment and were compared using the paired Student's t-test or the nonparametric Wilcoxon rank-sum test. Four polysomnographic recordings were obtained with pressurized nasal cannulae and were analyzed by analysis of variance.
  
  
  RESULTS
  The length of the mandible was increased, while the antero-posterior position of the maxilla remained stable. The posterior airway space was increased, the length of the tongue was preserved, and the hyoid bone was moved to a more anterior position. After Herbst treatment, sleep efficiency, sleep latency, rapid eye movement (REM) sleep latency, and percentage of REM sleep remained stable. We did observe a reduction (P < .05) in the relative proportions of stage 1 and stage 3-4 (from 4.30 ± 1.99 to 2.61 ± 1.83 for stage 1 and from 25.78 ± 7.00 to 19.17 ± 7.58 for stages 3-4) as well as an increase (P < .01) in the percentage of stage 2 after treatment (49.03 ± 6.25 to 56.90 ± 6.22). There was a reduction (P < .05) in the number of respiratory effort-related arousals (7.06 ± 5.37 to 1.31 ± 1.45 per hour of sleep) due to an increase (P < .01) in airway volume.
  
  
  CONCLUSIONS
  In the short term, the increase in airway space improved nocturnal breathing associated with the correction of mandibular retrognathism.
authors.affiliation: Department of Psychobiology, Universidade Federal de São Paulo, Brazil. tschutz@psicobio.epm.br
authors.forename: Teresa Cristina Barros
authors.initials: TC
authors.lastname: Schütz
authors.forename: Gladys Cristina
authors.initials: GC
authors.lastname: Dominguez
authors.forename: Marcia Pradella
authors.initials: MP
authors.lastname: Hallinan
authors.forename: Thays Crosara Abrahão
authors.initials: TC
authors.lastname: Cunha
authors.forename: Sergio
authors.initials: S
authors.lastname: Tufik
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D002508:Cephalometry; D002648:Child; D005260:Female; D006801:Humans; D006928:Hyoid Bone / Q000033:anatomy & histology; D008297:Male; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D008334:Mandible / Q000002:abnormalities; D019186:Mandibular Advancement / Q000295:instrumentation; D009058:Mouth Breathing / Q000628:therapy; D017289:Orthodontic Appliances, Functional; D010155:Palatal Expansion Technique / Q000295:instrumentation; D010614:Pharynx / Q000033:anatomy & histology; D017286:Polysomnography; D011446:Prospective Studies; D063173:Retrognathia / Q000628:therapy*; D012891:Sleep Apnea Syndromes / Q000628:therapy*; D012913:Snoring / Q000628:therapy; D018709:Statistics, Nonparametric