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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 94
PROCEEDINGS OF THE SEVENTH INTERNATIONAL CONFERENCE ON ENGINEERING COMPUTATIONAL TECHNOLOGY
Edited by:
Paper 152

On the Influence of Cortical Bone and Geometric Parameters in the Maxillofacial Micro-Screws used in Orthodontics

J. Marcé-Nogué1, A. Walter2, L. Gil1 and A. Puigdollers2

1Department of Strength of Materials and Structural Engineering, Universitat Politecnica de Catalunya, Terrassa, Spain
2Faculty of Dentistry, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain

Full Bibliographic Reference for this paper
, "On the Influence of Cortical Bone and Geometric Parameters in the Maxillofacial Micro-Screws used in Orthodontics", in , (Editors), "Proceedings of the Seventh International Conference on Engineering Computational Technology", Civil-Comp Press, Stirlingshire, UK, Paper 152, 2010. doi:10.4203/ccp.94.152
Keywords: orthodontics, micro-screws, cortical bone, finite element method.

Summary
The usage of titanium maxillofacial micro-screws in orthodontics requires good stability and good failure resistance. It is suggested that this stability is related to the quality and quantity of cortical bone [1], the geometric design of the micro-screw [2] or the value of the forces applied in it [3].

The basic purpose of this paper is to compare the performance of different commercial and existing orthodontic micro-screws using finite element analysis with a new point of view of the analysis: firstly, the angle of incidence of the traction force will be considered as an statistic analysis due to its random variation and secondly, the influence of geometrical parameters such as the thickness of the cortical bone and the drilling distance of the micro-screw into the bone will be studied, but, the place where the results are compared will be specially selected considering different observations of the results. Values will be recorded in places without artificial noise in which a convergence can be applied to improve the mesh.

Therefore, a series of computational simulations are done using the finite elements method package ANSYSR 12.0 to evaluate the stress state and the deformation of the micro-screws when they are loaded by a perpendicular traction force of 1 N. The obtained data helps optimal clinical decision before surgery.

Considering only the results obtained in this computational simulations, we can conclude that the results of stress and deformation can be understood as a fact that the shape and geometry of the micro-screw is of higher important in its behaviour and has an influence for each model studied. The influence of the cortical bone geometric parameters is important for the general behaviour of the micro-screws but hasn't different influence for each model studied.

Unlike previous studies, the random variability of the angle of incidence has been considered and the record of the maximum stresses close to geometrical singularities (as an artificial noise) has been avoided.

References
1
M. Motoyoshi, T. Yoshida, A. Ono, N. Shimizu, "Effect of cortical bone thickness and implant placement torque on stability of orthodontic mini-implant", Int J Oral Maxillofac Impl, 22, 779-784, 2007.
2
E.P. Holmgren, R.J. Seckinger, L.M. Kilgren, F. Mante, "Evaluating parameters of osseointegrated dental implants using finite element analysis-a two-dimensional comparative study examining the effects of implant diameter, implant shape, and load direction", J Oral Implantol, 24, 80-88, 1998. doi:10.1563/1548-1336(1998)024<0080:EPOODI>2.3.CO;2
3
S. Miyawaki, I. Koyama, M. Inoue, K. Mishima, T. Sugawara, T. Yamamoto, "Factors associated with the stability of titanium screws placed in the posterior region for orthodontic anchorage", Amer J Orthod Dentofac Orthop, 124, 373-378, 2003. doi:10.1016/S0889-5406(03)00565-1

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