title: An analytical evaluation of a new spring design for segmented space closure.
abstract: Contemporary segmented-arch space-closure springs require activation techniques that have the side effect of producing a significant amount of geometric nonlinearity. This nonlinearity makes these springs difficult to manipulate because it allows tipping during space closure which may be considered adverse. A new spring mechanism has been designed in response to these difficulties so that the advantages of the segmented-arch technique can be extended to those clinicians presently using simple sliding mechanics as a means of space closure. This spring mechanism has eliminated a significant portion of the geometric nonlinearity by using force-application devices (activators) such as elastics or coil springs as the means of activation. By selecting the right activator it may be possible to close an entire extraction site (approx. 7 mm) with one activation. The proposed mechanism essentially consists of two units: an anchorage unit (M/F = 18 mm), and a translational unit (M/F = 11 mm). These units are combined in order to achieve anterior retraction, posterior protraction, or a combination of the two, which is termed reciprocal-attraction. The finite-element method was used in place of bench studies to test the new spring design. The commonly used reciprocal-attraction spring tested with a nearly constant M/F ratio equal to 11 +/- 1 mm over an effective force range of 50 gm to 450 gm. The results from the other two tests also showed that precisely controlled couple-to-force (M/F) ratios can be maintained over a wide range of effective forces.
authors.affiliation: University of Louisville, USA.
authors.forename: T C
authors.initials: TC
authors.lastname: Rinaldi
authors.forename: B E
authors.initials: BE
authors.lastname: Johnson
mesh_terms: D000202:Activator Appliances; D003198:Computer Simulation; D003799:Dental Stress Analysis; D004548:Elasticity; D006801:Humans; D016382:Orthodontic Appliance Design; D009969:Orthodontic Wires; D009971:Orthodontics, Corrective / Q000379:methods*; D013193:Stainless Steel; D013314:Stress, Mechanical; D014081:Tooth Extraction
chemical_list: D013193:Stainless Steel