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Force Systems in the Initial Phase of Orthodontic Treatment-a Comparison of Different Leveling Archwires.

Fuck LM, Drescher D

Poliklinik für Kieferorthopädie, Moorenstr. 5, Geb. 18.21, 40225, Düsseldorf, Germany, fuck@uni-duesseldorf.de.

BACKGROUND AND AIM: The determination of orthodontically-effective forces and moments places great demands on the technical equipment. Many patients report severe pain after fixed appliance insertion. Since it is assumed that pain from orthodontic appliances is associated with the force and moment levels applied to the teeth and since the occurrence of root resorption is a commom therapeutic side effect, it would seem important to know the actual magnitudes of the components of the active orthodontic force systems. The aim of the present study was therefore to measure initial force systems produced by different leveling archwires in a complete multibracket appliance and to assess whether force and moment levels can be regarded as biologically acceptable or not. MATERIAL AND METHODS: The actual bracket position in 42 patients was transferred onto a measurement model. Forces and moments produced by a superelastic nickel-titanium (NiTi) archwire, a 6-strand stainless steel archwire, and a 7-strand superelastic NiTi archwire were determined experimentally on different teeth. RESULTS: Average forces and moments produced by the superelastic NiTi archwires were found to be the highest. In spite if their larger diameter, the stranded archwires' average force and moment levels were lower, especially that of the stranded superelastic archwire. Nevertheless, maximum force levels sometimes exceeded recommended values in the literature and must be considered as too high. CONCLUSIONS: The measured archwires' initial force systems differed significantly depending on the type of archwire and its material structure. Stranded archwires produced lower force and moment levels, and we recommend their use in the initial phase of orthodontic treatment.

Published 31 January 2006 in J Orofac Orthop, 67(1): 6-18.
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