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Is bodily advancement of the lower incisors possible?

Some Class II malocclusions are due, at least in part, to a retruded lower dental arch relative to the mandibular body. The purpose of this study was to determine if a direct anterior force on the lower incisors could lead to bodily movement of these teeth. Twenty-seven patients (9 males, 18 females; mean age: 9.8 years) were treated with a reverse headgear (RHG) in the lower dental arch combined with labial root torque of the lower incisors. An activator was added to disclude the arches. This group was compared with 26 patients (10 males, 16 females; mean age: 9.7 years) treated with an activator combined with conventional posterior extraoral traction on the upper molars. All patients had a second stage of treatment with fixed appliances and Class II elastic wear. At the end of treatment, all patients had a Class I relationship and a normal overjet. Lateral cephalograms were taken before (T1), after the first stage (T2), and at the end of active (T3) treatment. Independent sample t-tests were used to assess the differences between the two groups of patients. In the RHG group, despite the applied root torque, the lower incisors showed anterior crown tipping. Labial root displacement was not observed. At T2, this labial tipping partially relapsed. Furthermore, the use of RHG appeared to decrease bone apposition in the anterior part of the symphysis, leading to a reduction in width. Bodily advancement of the lower incisors was not achieved with the application of labial root torque and anteriorly directed force on the mandibular arch. The width limit of the lower anterior apical base should be respected during orthodontic treatment planning.