SPEED APPLIANCE MECHANICS The SPEED Appliance is a versatile orthodontic edgewise mechanism. Although it can be used in conjunction with other bracket designs, it is most effective when used as a homogeneous orthodontic system. The SPEED System™ easily lends itself to, and enhances the results of all treatment philosophies. Many SPEED users have found that they can achieve their high treatment standards most effectively by utilizing a treatment method which fully exploits the mechanical benefits the system has to offer. These consist primarily of SPEED’s precise tooth control, wide interbracket span, and predictably low frictional resistance. Most importantly, it is recommended that clinicians keep forces to a minimum. The benefits of using threshold forces are well documented and enhanced comfort for the patient. Whatever system of mechanics is used, it is recommended that it be used in conjunction with light ‘Threshold Forces’. 24 THRESHOLD FORCE SELECTION The classification of orthodontic forces is very subjective. What one clinician may term “light”, another may term “heavy”. Orthodontic forces have conventionally been classified as: Light 50 - 100 gms Medium 100 - 200 gms Heavy 200 - 300 gms When using the friction reduced SPEED System™, it is possible to use “threshold forces”. These forces are selected to overcome the designated tooth’s resistance without exceeding capillary blood pressure. Such extremely light forces range typically from approximately 30-80 gm and provide maximum movement, while placing a minimum burden on anchorage. The individual selection of threshold forces for clinical applications can be quite difficult and still remains an art to a considerable extent. This selection process may be affected by such variables as: • Archwire size and material • Individual variations in tissue response • Parafunctional habits such as clenching • Normal functional forces • Tendency toward calculus formation • Lip and cheek muscle tonicity • The extent to which anchorage can be strained • The periodontal ligament surface areas of involved teeth • Frictional factors such as the pressure between contacting surfaces, surface finishes and the effects of lubricants Some clinicians have found it useful to monitor and modify their force levels with a calibrated intra-oral force gauge. Use of a force gauge enables clinicians to apply the optimal force level for a specific required movement. (A 15-150 gram dynamometer is available from Jonard Industries Corp. - www.jonard.com - (914) 793-0700 for approx. $85.00 USD).
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