Original article
English
El-Sheikh MM, Godfrey K, Manosudprasit M, Viwattanatipa N.
Faculty of Dentistry, Garyounis University, Abdul Monem Riad, Benghazi, Libya.
World J Orthod. 2007 Spring;8(1):30-6.
Abstract
Aim: The Forsus fatigue-resistant device spring is a 3-piece telescoping compression spring used for Class II correction. The aims of this study were: (1) to measure the mean force delivered at different amounts of deflection; (2) to determine and compare the mean stiffness between loading and unloading; and (3) to determine the resilience of the fatigue-resistant device springs. Material and methods: Twelve fatigue-resistant device springs were tested with a universal testing machine and Winrcon software, with the load cell of 100 N, crosshead speed at 0.5 mm/second. Force-deflection data during loading and unloading were recorded at 2-mm intervals up to 12 mm compression. Results: (1) The mean force-deflection loading and unloading curves generally were linear, with a small area of hysteresis; (2) the loading mean stiffness (19.4 g/mm) was significantly greater than the unloading mean stiffness (18 g/mm), although this is clinically insignificant; (3) fatigue-resistant device springs exhibited good resiliency. A calibrated table of force-deflection of fatigue-resistant device springs is presented for clinicians to select the appropriate length of the device for the particular orthodontic force needed.
Keywords: Force-deflection characteristics of the fatigue-resistant device spring: an in vitro study
Link/DOI: http://www.quintpub.com/journals/wjo/abstract.php?iss2_id=227&article_id=2655&article=5&title=Force-deflection%20Characteristics%20of%20the%20Fatigue-Resistant%20Device%20Spring:%20An%20in%20Vitro%20Study