An analysis of force between attractive magnets used in orthodontics

J Coll Physicians Surg Pak. 2005 Oct;15(10):634-7.


Objective: To compare the results of hard and soft attractive magnet combinations to the gold standard Neodymium Iron Boron Magnets used for extrusion of impacted maxillary canines.

Design: Experimental and comparative study.

Place and duration of study: Eastman Dental Institute and Hospital, London, UK in collaboration with Department of Physics and Astronomy University College of London (UCL) during 1996-1998.

Material and methods: In vitro experiments with combinations of hard and soft magnets of different morphologies. Load Cell Transducer was used to record the force levels in grams with magnets placed in different vertical, horizontal and angular offsets.

Results: Three-dimensional mesh plots were created to visualize force level decay with increasing distance. The results were compared with previous study on hard magnet combinations only and observed for "edge effect". The present study force levels were very low albeit the edge effect was negligible.

Conclusion: Although the edge effect phenomenon present with powerful hard magnets was minimal or nearly absent with the hard and soft magnet combination--the overall force levels were too low to be of any use in clinical scenario for extrusion of deep impacted canines.

MeSH terms

  • Equipment Design
  • Humans
  • Magnetic Field Therapy*
  • Tooth, Impacted / therapy*