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Updated: Jul 19, 2026
3D Imaging of PDL Collagen Fibers during Orthodontic Tooth Movement in Mandibular Murine Model
Published on: April 15, 2021
Inactivated periods of constant orthodontic forces related to desirable tooth movement in rats
T Kameyama1, Y Matsumoto, H Warita
1Science Department of Orofacial Development and Function, Tokyo Medical and Dental University, Japan. kame.orts@tmd.ac.jp
Aim:
To examine the effects of inactive periods of force on the amount of tooth displacement and root resorption during experimental tooth movement in rats.
Sample:
Sixty 11-week-old male Sprague-Dawley rats.
Method:
The maxillary first molar (M1) was moved mesially using a removable titanium-nickel alloy closed coil spring for 14 days. The rats were divided into four groups with, 0, 1, 4, and 9 hours of inactivation per day.
Results:
Tooth displacement in the 0- and 1-hour groups was significantly greater than that in the 9-hour group. The area of root resorption in the 4- and 9-hour groups was significantly less than that in the 0- and 1-hour groups. There was no significant difference in root resorption between 0- and 1-hour groups, and also between 4- and 9-hour groups.
Conclusion:
The distance of tooth displacement gradually decreased as the inactive period increased, whereas root resorption suddenly decreased between 1 and 4 hours of inactive orthodontic force.
