An assessment of skeletal and dental responses to the functional magnetic system (FMS)

Correction of a skeletal Class II malocclusion with functional appliances h as been accepted as a viable treatment modality. However, its mechanism of action is still disputed. This retrospective study compared 20 Class II pat ients treated with the functional magnetic system (FMS) with Class I and Cl ass II groups (the control groups) of 20 untreated subjects each. Dental an d skeletal changes were compared using serial lateral cephalograms. The FMS group differed significantly from the control groups in 15 of 24 parameter s. The great,-increase in articulare-gnathion distance (3.07 mm) attributed to the attractive magnetic component of the FMS dictates a prolonged propu lsion of the mandible. The skeletal:dental response ratio was 1:2 for the a nterior region and 1:1 for the posterior region. The dental and skeletal pa rameters demonstrated a synergistic response in the maxilla and a competiti ve response in the mandible. This means that greater maxillary molar distal movement and incisor retroclination resulted in a more significant restrai nt of point A. In contrast, increasing the mandibular molar mesial movement and the incisor proclination accompanied less advancement of the pogonion. Although the skeletal contribution to the resolution of the malocclusion w as less than the dental contribution (anteriorly, one third), the functiona l correction response was found to be regulated by skeletal factors.