Journal Article

Stability of connected mini-implants and miniplates for skeletal anchorage in orthodontics

Michael T. C. Leung, A. Bakr M. Rabie and Ricky W. K. Wong

in The European Journal of Orthodontics

Published on behalf of European Orthodontics Society

Volume 30, issue 5, pages 483-489
Published in print October 2008 | ISSN: 0141-5387
Published online May 2008 | e-ISSN: 1460-2210 | DOI:
Stability of connected mini-implants and miniplates for skeletal anchorage in orthodontics

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The aim of this study was to examine the primary stability of connected mini-implants and miniplates. Three different skeletal anchorage systems were investigated: (1) two 1.5 mm diameter cylindrical mini-implants connected with a 0.021 × 0.025 inch stainless steel (SS) wire, (2) two 1.6 mm diameter tapered mini-implants connected with a 0.021 × 0.025 inch SS wire, and (3) two 2.0 mm diameter cylindrical mini-implants connected by a titanium locking miniplate. Fifteen standardized bovine bone specimens were prepared, five specimens for each experimental group. The connected mini-implants were fixed on the bone specimens. The systems underwent uniaxial pull-out tests at the midpoint of the connecting wire or miniplate using a mechanical testing machine. One-way analysis of variance was used to determine the difference of the pull-out test results between the groups.

Both the titanium miniplate and SS wire connection systems showed severe deformation at the screw head, which broke before the mini-implants failed. The 2.0 mm miniplate system showed the highest pull-out force (529 N) compared with the other two wire connection systems (P < 0.001). The 2.0 mm system was also stiffer than the 1.6 and 1.5 mm systems (P < 0.001). The yield force of the 2.0 mm miniplate (153 N) was significantly higher than the 1.5 mm (88 N) and 1.6 mm (76 N) systems (P < 0.001).

This in vitro study demonstrated that the connection of two mini-implants with a miniplate resulted in higher pull-out force, stiffness, and yield force to resist pulling force and deformation. Such a set-up could thus provide a stable system for orthodontic skeletal anchorage.

Journal Article.  3158 words.  Illustrated.

Subjects: Restorative Dentistry and Orthodontics

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