Korean J Orthod.  2008 Oct;38(5):304-313. 10.4041/kjod.2008.38.5.304.

Factors influencing primary stability of miniplate anchorage: a three-dimensional finite element analysis

• Lee NK
• Choi DS
• Jang IS
• Cha BK

• KMID: 2273917
• DOI: http://doi.org/10.4041/kjod.2008.38.5.304

Abstract

OBJECTIVE
The purpose of this study was to evaluate the stress distribution in bone and displacement distribution of the miniscrew according to the length and number of the miniscrews used for the fixation of miniplate, and the direction of orthodontic force.
METHODS
Four types of finite element models were designed to show various lengths (6 mm, 4 mm) and number (3, 2) of 2 mm diameter miniscrew used for the fixation of six holes for a curvilinear miniplate. A traction force of 4 N was applied at 0degrees, 30degrees, 60degrees and 90degrees to an imaginary axis connecting the two most distal unfixed holes of the miniplate.
RESULTS
The smaller the number of the miniscrew and the shorter the length of the miniscrew, the more the maximum von Mises stress in the bone and maximum displacement of the miniscrew increased. Most von Mises stress in the bone was absorbed in the cortical portion rather than in the cancellous portion. The more the angle of the applied force to the imaginary axis increased, the more the maximum von Mises stress in the bone and maximum displacement of the miniscrew increased. The maximum von Mises stress in the bone and maximum displacement of the miniscrew were measured around the most distal screw-fixed area.
CONCLUSIONS
The results suggest that the miniplate system should be positioned in the rigid cortical bone with 3 miniscrews of 2 mm diameter and 6 mm length, and its imaginary axis placed as parallel as possible to the direction of orthodontic force to obtain good primary stability.

Keyword

Miniplate; Anchorage; Primary stability; Finite element analysis

MeSH Terms

Axis, Cervical Vertebra
Displacement (Psychology)
Finite Element Analysis
Traction