Effects of gradually increasing force generated by permanent rare earth magnets for orthodontic tooth movement

Ryo Tomizuka, Hiroyasu Kanetaka, Yoshinaka Shimizu, Akihiro Suzuki, Kaoru Igarashi, Hideo Mitani

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Objective: To examine the effects of gradually increasing force generated by permanent rare earth magnets for orthodontic tooth movement by using a novel experimental rat model and computer simulation. Materials and Methods: Fifty-five male rats (age 18 weeks) were used as animal experiments. Magnetic (experimental groups) or titanium (control group) cuboids (1.5 x 1.5 x 0.7 mm) were bonded to the lingual surface of the maxillary first molars. The initial distance between materials was 1.0 mm, generating 4.96 gf (experimental group I), or 1.5 mm, generating 2.26 gf (experimental group II). Tooth movement was measured and periodontal structures were observed with microfocus x-ray computed tomography radiographs. Results: The distance between the magnets decreased with time in experimental groups I and II (P < .001), whereas there was no tooth displacement in the control group. Experimental group I showed rapid tooth movement in the initial phase followed by slower tooth movement. Experimental group II showed gradual tooth movement. Horizontal sections on microfocus computed tomgraphy radiographs revealed no pathological changes, such as root resorption, on the compressed side in the experimental groups. Conclusions: The initial light force and gradual increasing force in magnetic attractive force induced effective tooth movement in rats without inducing any pathological changes.

Original languageEnglish
Pages (from-to)1004-1009
Number of pages6
JournalAngle Orthodontist
Volume76
Issue number6
DOIs
Publication statusPublished - 2006 Nov

Keywords

  • Attractive force
  • Gradually increasing force
  • Rare earth magnet
  • Rat
  • Tooth movement

ASJC Scopus subject areas

  • Orthodontics

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