In vitro assessment for primary stability of self-drilling orthodontic mini-implants: Pull-out testing at different insertion angles

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Title	In vitro assessment for primary stability of self-drilling orthodontic mini-implants: Pull-out testing at different insertion angles
Authors	Poulomi Roy¹, Riddhi Chawla², Ashish Kumar^3,*, Harshit Pandya⁴, Shikha Rastogi Gupta⁴ & Kashyap Shah⁵
Affiliation	¹Department of Orthodontics and dentofacial orthopaedics, Burdwan Dental College and Hospital, Burdwan, West Bengal, India; ²Department of Dentistry, School of Dentistry, Central Asian University, Uzbekistan; ³Department of Orthodontics and Dentofacial Orthopaedics, NIMS Dental College & Hospital, NIMS University, Rajasthan, Jaipur, India; ⁴Department of Orthodontics and Dentofacial Orthopaedics, Geetanjali Dental College, Udaipur, India; ⁵Department of Orthodontics and Dentofacial Orthopedics, Goenka Research Institute of Dental Science, Pethapur, Gandhinagar, Gujarat, India; *Corresponding author
Email	Poulomi Roy - E-mail: drpoulomi.r@gmail.com Riddhi Chawla - E-mail: r.chawla@centralasian.uz Ashish Kumar - E-mail: drashish055@gmail.com Harshit Pandya - E-mail: pandya1988@gmail.com Shikha Rastogi Gupta - E-mail: drshikharastogi@gmail.com Kashyap Shah - E-mail: drkashyapshah@gmail.com
Article Type	Research Article
Date	Received May 1, 2026; Revised May 31, 2026; Accepted May 31, 2026, Published May 31, 2026
Abstract	Achieving optimal primary stability of orthodontic mini-implants remains a clinical challenge because the ideal insertion angle for self-drilling mini-implants has not been clearly established. Therefore, it is of interest to evaluate and compare the primary stability of self-drilling orthodontic mini-implants inserted into artificial bone blocks at four different angles (30°, 45°, 60° and 90°) using pull-out resistance testing. Eighty titanium alloy mini-implants (1.6 mm diameter, 8 mm length) were randomly allocated into four groups (n=20 each) and inserted into standardized synthetic bone blocks simulating D2 bone density with a custom angular guide, followed by pull-out testing in a universal testing machine at a crosshead speed of 1 mm/min. Mini-implants placed at 60° showed the highest mean pull-out force (324.67 ą 28.43 N), followed by 45° (298.52 ą 31.76 N), 90° (267.38 ą 25.91 N) and 30° (231.14 ą 33.82 N), with statistically significant differences between the groups. Thus, insertion at 60° to the bone surface provided the high primary stability. It may be considered the biomechanically most favorable angulation for self-drilling orthodontic mini-implants.
Keywords	Orthodontic mini-implant, primary stability, insertion angle, pull-out test, temporary anchorage device (TAD)
Citation	Roy et al. Bioinformation 22(5): 2792-2798 (2026)
Edited by	Hiroj Bagde
ISSN	0973-2063
Publisher	Biomedical Informatics
License	This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. This is distributed under the terms of the Creative Commons Attribution License.