Class II correction improves nocturnal breathing in adolescents

OBJECTIVE: To examine modifications in sleep pattern and in craniofacial morphology of adolescents with mandibular retrognathism. MATERIALS AND 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.