Maxillary expansion in Class II correction with orthopedic cervical headgear. A posteroanterior cephalometric study.

Class-II, division-1 malocclusion appears to be associated with a narrow maxilla. A Class-II malocclusion may be corrected to a Class-I relationship in children using a cervical headgear provided that the narrow maxilla is expanded. This expansion is possible using headgear by dental cast analysis, but this has not been confirmed by cephalometry. We studied the effects of orthopedic cervical headgear on dental and skeletal facial widths in 40 children aged 9.1 (7.2-11.5) who had Class-II, division-I malocclusions. The headgear consisted of a long outer bow bent 15 degrees upward and a large inner bow expanded by 10 mm. Posteroanterior cephalographs and dental casts were taken before and after treatment. The results were compared with the control values presented in the literature. The malocclusion was treated to a Class-I relationship in all children. The average treatment time was 1.6 (0.3-3.1) years. The maxilla was widened significantly (P < .0001). The upper first molar width (um-um) and maxillary width (mx-mx) increased 3.2 and 1.6 mm/y, respectively. Maxillary widening was also observed in the nasal structure as indicated by an increase in lateronasal width (lap-lap) by 1.0 mm/y (P < .005). With maxillary widening, the mandibular dental arch widened spontaneously. The lower first molar width (lm-lm) increased 0.8 mm/y, which was more than the increase in the controls (P < .0001). However, the antegonial width (ag-ag) remained unaffected. By using a widened inner bow in headgear therapy with Class-II malocclusions, a widening of maxilla and nasal cavity may be obtained.