Related Experiment Video
Updated: Jun 13, 2026
11:51
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
Summary
Mini-implant stability was assessed using placement and removal torques. Placement torque correlates with age and bone thickness, indicating factors influencing initial stability.
Area of Science:
- Orthodontics
- Dental Implantology
- Biomaterials Engineering
Background:
- Mini-implants are crucial for orthodontic anchorage.
- Evaluating mini-implant stability is essential for successful treatment outcomes.
- Torque measurements provide an objective index of implant stability.
Purpose of the Study:
- To evaluate mini-implants' placement and removal torques.
- To identify factors influencing initial and long-term mini-implant stability.
- To determine the correlation between torque values and clinical parameters.
Main Methods:
- 134 machine-surfaced mini-implants (1.6x8 mm) were placed in posterior alveolar bone.
- Placement and removal torques were measured using a torque screwdriver.
- Relationships between torques, placement period, age, sex, and cortical bone thickness were analyzed.
Main Results:
- Average placement torque was ~8 N cm; average removal torque was ~4 N cm.
- A removal torque of 4 N cm suggests adequate anchorage.
- Placement torque significantly correlated with patient age and maxillary cortical bone thickness.
Conclusions:
- Mini-implant stability is influenced by age and bone thickness at placement.
- Removal torque did not significantly correlate with placement duration, age, sex, or bone thickness.
- A removal torque of 4 N cm indicates sufficient anchorage for orthodontic applications.
