Histological evaluation of the effects of initially light and gradually increasing force on orthodontic tooth movement

Ryo Tomizuka, Yoshinaka Shimizu, Hiroyasu Kanetaka, Akihiro Suzuki, Sachiko Urayama, Masayoshi Kikuchi, Hideo Mitani, Kaoru Igarashi

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)

Abstract

Objective: To investigate histologically the effect of initially light and gradually increasing force on tooth movement in the rat. Materials and Methods: Cuboids made of neodymium-iron-boron magnets (experimental groups) or titanium (control group) were bonded to the lingual surface of the right and left maxillary first molars of 18-week-old male Wistar rats. The initial distances between materials were 1.0 mm generating 4.96 gf (experimental group 1) and 1.5 mm generating 2.26 gf (experimental group 2). In three groups, rats were killed 1, 3, 7, 10, or 14 days after treatment. Histological sections were prepared and stained with hematoxylin and eosin or for tartrate-resistant acid phosphatase (TRAP) activity. The number of TRAP-positive osteoclasts was counted, and the relative hyalinized area was measured on the pressure side of periodontal ligament. Results: There were significant differences in the number of osteoclasts among the three groups (P < .05). On days 1 and 3, the numbers of osteoclasts in experimental group 2 were greater than in experimental group 1. There were significant differences in the relative hyalinized area between the control group and experimental group 1 (P < .01) and between experimental groups 1 and 2 (P < .01). On days 1 and 3, the hyalinized area in experimental group 1 was larger than in experimental group 2. Conclusion: Initially light and gradually increasing force induced tooth movement without the lag phase and showed smooth recruitment of osteoclasts and inhibition of hyalinization.

Original languageEnglish
Pages (from-to)410-416
Number of pages7
JournalAngle Orthodontist
Volume77
Issue number3
DOIs
Publication statusPublished - 2007 May

Keywords

  • Gradually increasing force
  • Hyalinization
  • Initially light force
  • Osteoclasts
  • Rat
  • Tooth movement

ASJC Scopus subject areas

  • Orthodontics

Fingerprint Dive into the research topics of 'Histological evaluation of the effects of initially light and gradually increasing force on orthodontic tooth movement'. Together they form a unique fingerprint.

Cite this