title: An experimental method for in vivo analysis of biomechanical asymmetries of the periodontium.
abstract: For analysis of the initial tooth movement in vivo, an optical measuring apparatus with a resolution of 0.001 degree for rotation or 0.5 micron for translation respectively has been developed. Its design is described in detail. Because of its high sensitivity it is experimentally feasible to investigate the biomechanical properties of the periodontium under force application and to determine if it makes any difference whether a tooth is rotated mesially or distally out of its neutral position. For that purpose moments with defined time responses are buccally applied to premolars by means of a cardan shaft and the corresponding rotational angle-time characteristics are recorded. As expected, first measurements show sign symmetry for widely spaced teeth. In the case of pronounced anterior crowding, however, asymmetry seems to occur in such a manner that the force system has to overcome a threshold in order to rotate the tooth distally. Additionally, the periodontium may be subject to a sign-dependent rigidity. In all cases, the movement is limited to some degree.
authors.affiliation: Department of Orthodontics, University of Göttingen, Germany.
authors.forename: Dankmar
authors.initials: D
authors.lastname: Ihlow
authors.forename: Michael
authors.initials: M
authors.lastname: Cronau
authors.forename: Dietmar
authors.initials: D
authors.lastname: Kubein-Meesenburg
authors.forename: Gernot
authors.initials: G
authors.lastname: Heine
authors.forename: Henning
authors.initials: H
authors.lastname: Dathe
authors.forename: Claudia
authors.initials: C
authors.lastname: Hansen
authors.forename: Hans
authors.initials: H
authors.lastname: Nägerl
mesh_terms: D001641:Bicuspid / Q000503:physiopathology; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D004548:Elasticity; D020342:Finite Element Analysis; D006801:Humans; D008310:Malocclusion / Q000503:physiopathology; D016910:Orthodontic Brackets; D010519:Periodontium / Q000503:physiopathology*; D012399:Rotation; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation; D012984:Software; D014087:Tooth Movement Techniques / Q000379:methods*