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Updated: Jun 13, 2026
An Improved Mechanical Testing Method to Assess Bone-implant Anchorage
Published on: February 10, 2014
Factors affecting the long-term stability of orthodontic mini-implants
Mitsuru Motoyoshi1, Miwa Uemura, Akiko Ono
1Department of Orthodontics, Division of Clinical Research, Dental Research Center, School of Dentistry, Nihon University, Tokyo, Japan. motoyoshi@dent.nihon-u.ac.jp
Introduction:
The placement and removal torques of mini-implants were evaluated as an index of implant stability. We examined factors affecting the initial and long-term stability of mini-implants.
Methods:
We measured the placement and removal torques of 134 mini-implants placed in buccal posterior alveolar bone and assessed the relationships among placement and removal torques, placement period, age, sex, and cortical bone thickness. The mini-implants were machine-surfaced, 1.6 mm in diameter and 8 mm long. A torque screwdriver was used to measure the peak torque values.
Results And Conclusions:
The placement and removal torques averaged approximately 8 and 4 N cm, respectively. A torque of 4 N cm suggests sufficient anchorage capability for mini-implants. No significant correlation between placement and removal torques was found. Placement torque was significantly related to age and cortical bone thickness in the maxilla, whereas removal torque was not significantly related to placement period, age, sex, or cortical bone thickness.
