Related Experiment Video
Updated: Aug 8, 2025
04:11
Author Spotlight: Insights into an Efficient Murine Maxillary Orthodontic Model Protocol
Published on: October 27, 2023
807
Difference in apical resorption activity during rat molar root formation in response to mechanical force
Yixin Lou1,2, Yoshiro Matsumoto1, Sachiko Iseki2
1Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
European Journal of Orthodontics
|February 27, 2023
Summary
Mechanical force applied to developing rat molars influenced root resorption. Force delayed root sheath development, inhibiting external apical root resorption (EARR) and odontoclast differentiation.
Area of Science:
- Dental research
- Orthodontics
- Developmental biology
Background:
- Root development involves complex biological processes.
- Mechanical forces are used in orthodontics to move teeth.
- Understanding root resorption during tooth movement is crucial.
Purpose of the Study:
- To investigate differences in apical root resorption activity during root development in response to mechanical force in vivo.
- To analyze the impact of mechanical force on root morphology and odontoclastogenesis.
Main Methods:
- Maxillary first molars from rats at postnatal day (PN) 21 (developing) and PN35 (completing) were used.
- A 3 cN mechanical force was applied, and samples were collected at PN28 and PN42.
- Micro-focus X-ray computed tomography, immunohistochemistry, and qPCR were employed to assess root morphology and resorption activity.
Main Results:
- Force application on developing roots (PN28) showed intact histology but no apical resorption; lateral resorption was observed.
- External apical root resorption (EARR) occurred in later stages (PN42) and on mesiobuccal roots.
- Osteopontin expression changed, while osteoprotegerin and RANKL expression showed no significant change in early stages.
Conclusions:
- Force application delayed Hertwig's epithelial root sheath (HERS) dissociation on the compression side.
- This delay inhibited cementogenesis, leading to reduced odontoclast differentiation and prevention of EARR.
- The findings suggest a mechanism by which mechanical force can modulate root resorption during development.
