Stability of the lower labial segment following orthodontic treatment--a comparison of treatment with Andresen and Begg appliances.

Abstract

This retrospective cephalometric study of Class II division 1 malocclusions investigates the effects on the lower labial segment of two forms of orthodontic treatment. Non-extraction Andresen myofunctional therapy and first premolar extraction Begg treatment are compared to the lower incisor changes found in appropriate non-extraction and first premolar extraction control groups, which also presented with Class II division 1 malocclusions. Using four angular and two linear measurements, the lower labial segment was found to procline during Andresen therapy (1-2 degrees, 1-2 mm), and on withdrawal of the appliance it retroclined by about one-half of the in-treatment proclination (0.4-0.8 degrees, 0.1-0.5 mm). During extraction Begg mechanics, the lower incisors were found to retrocline (1.3-1.5 degrees, 0.4-0.9 mm), and they continued to retrocline following removal of the appliance (0.2-3.0 degrees, 0.8-1.1 mm). In general, the variables used to measure lower incisor position demonstrated only very small changes, and were near method error. The reliability of these changes are discussed. It is considered that the axial inclination of the lower incisor in relation to the mandibular plane is the most consistent and therefore still the most useful clinical measurement of lower incisor change available from cephalometric radiographs.