Das funktionskieferorthopädische Magnetsystem (FMS) nach Vardimon - Teil 1. Dreidimensionale Analyse des Kraftsystems anziehender Magnete

The functional magnetic system (FMS) is a removable functional applianee which induces mandibular advance by means of mandibular and maxillary magnets in an attracting configuration. The maxillary and mandibular plates are each equipped with 2 cylindrically shaped cobalt-samarium magnets 4 mm in diameter and 3 mm in height, which are welded into stainless steel housings. The foice system of this magnetic configuration was analyzed using the orthodontic measurement and simulation system (OMSS). OMSS simulated the mandibular jaw movements by separating the installed magnets vertically corresponding to a mouth opening of X=-10 mm, transversally (right excursion. +/left excursion. -) at Y=±10 mm and sagittally (anterior dispfacement.+/posterior displacement, -) at Z=±10 mm. The resolting 2D and 3D force/displacement diagrams elucidate the outstanding centripetal-spatial orientation characferistics of the funetional magnetic appliance in eference to the full overlap bronght about by the attraction of the mandibular magnet by the maxillary magnet. The maximum centripetal forces reached a value of approximately F_Y,max=0.65 N for the vertical attracting force at full overlap of the mandibular and maxillary magnets (X=0.55 mm, Y=Z=0 mm) a value of F_{Y, max}=0.65 N for the medial shearing force at a partial transversal overlap (Z=0, Y=±2 mm and Y=±6 mm), and for the sagittal shearing force a value of F_{Z, max}=1.2 N at a partial sagiftal overlap of the magnets (Y=0 mm, Z=±2 mm). The maximum displacements from which the mandibular magnet is attracted to the constructive protrusive closed position, which is the point at which the mandible is postured in the predetermined advanced closed position and which equals X=Y=Z=0, were found to be at a mouth, opening of X=-6 mm (at Y=Z=O) a transversal shift of Y=±10 mm. and an overjet of Z=-6 mm. Beyond these boundaries the attractive force system reaches almost zero level and converts in the Z direction in part into weak repulsive forces. Additional mechanical aids, which counteract the repulsive force and increase the mandibular guidance, have to be incorporated into the FMS Thus the FMS as an adunct to functional or skeletal correction of mid-line deviation results in an improved performance of mandibular advancement.