[Evaluation of the maxillary basal bone and molar change of skeletal Class II malocclusion treated by sagittal-guidance Twin-block].

Purpose: To investigate the effects of sagittal-guidance Twin-block appliance on maxillary basal bone and buccal segment distalization in developing Angle Class II division 1 malocclusion.

Methods: The measurement data of anterior-posterior direction and vertical dimension between pretherapy and post-treatment, including 34 developing Angle Class II division 1 patients with sagittal-guidance Twin-block and non-extraction treatment, were quantitatively analyzed by X-ray cephalometry and Pancherz. SPSS 20.0 software package was used for statistical analysis.

Results: After orthopedic treatment, the maxilla significantly retruded (0.68 mm, P<0.01), the maxillary molars moved posteriorly (1.33 mm, P<0.01). After orthodontic treatment, the maxillary bone still turned out posteriorly (0.65 mm, P<0.05), and the molar teeth were slightly distalized (0.53 mm, P>0.05).

Conclusions: The correction of developing Angle Class II division 1 malocclusion can be achieved by sagittal-guidance Twin-block.