Journal List > Korean J Orthod > v.38(4) > 1043553

Korean J Orthod. 2008 Aug;38(4):228-239. Korean.
Published online August 30, 2008.
Copyright © 2008 Korean Association of Orthodontists
Cortical bone strain during the placement of orthodontic microimplant studied by 3D finite element analysis
Okhyun Nam, DDS, MSD,a Wonjae Yu, DDS, MSD, PhD,b and Hee-Moon Kyung, DDS, MSD, PhDc
aGraduate student, Department of Orthodontics, School of Dentistry, Kyungpook National University, Korea.
bAssistant professor, Department of Orthodontics, School of Dentistry, Kyungpook National University, Korea.
cProfessosr, Department of Orthodontics, School of Dentistry, Kyungpook National University, Korea.

Corresponding author: Wonjae Yu. Department of Orthodontics, School of Dentistry, Kyungpook National Universisty, 188-1, Samdeok-dong 2-ga, Jung-gu, Daegu 700-412, Korea. +82 53 420 4991, Email:
Received February 01, 2008; Revised June 05, 2008; Accepted June 08, 2008.



The aim of this study was to evaluate the strain induced in the cortical bone surrounding an orthodontic microimplant during insertion.


A 3D finite element method was used to model the insertion of a microimplant (AbsoAnchor SH1312-7, Dentos Co., Daegu, Korea) into 1 mm thick cortical bone with a pre-drilled hole of 0.9 mm in diameter. A total of 1,800 analysis steps was used to simulate the 10 turns and 5 mm advancement of the microimplant. A series of remesh in the cortical bone was allowed to accommodate the change in the geometry accompanied by the implant insertion.


Bone strains of well higher than 4,000 microstrain, the reported upper limit for normal bone remodeling, was observed in the bone along the whole length of the microimplant. At the bone in the vicinity of the screw tip, strains of higher than 100% was recorded. The insertion torque was calculated at approximately 1.2 Ncm which was slightly lower than those measured from the animal experiment using rabbit tibias.


The insertion process of a microimplant was successfully simulated using the 3D finite element method which showed that bone strains from a microimplant insertion might have a negative impact on physiological remodeling of bone.

Keywords: Microimplant; Strain during insertion; 3D finite element method; Rabbit experiment


Fig. 1
Geometry of microimplant and cortical bone specimen together with axis system and important dimensions (implant: rigid, cortical bone: rigid-plastic, unit: mm). A, Geometry model; B, initial mesh of the cortical bone constructed of 30,706 tetrahedral element.
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Fig. 2
Material property of cortical bone used in the present study (cf. Table 1).
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Fig. 3
A-L, Effective strain distribution in the cortical bone at 12 separate stages of microimplant insertion.
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Fig. 4
A-J, Strain distribution in the cortical bone at 9 separate stages of microimplant insertion with strains cut off at 4000µ-strain.
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Fig. 5
Estimated insertion torque during microimplant placement of FEM model.
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Fig. 6
Insertion torque measured during microimplant placement into a rabbit tibia of 1.0 - 1.5 mm thickness. A, Upper part of tibia; B, lower part of tibia.
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Table 1
Mechanical properties (bone and implant materials)
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1. Maniatopoulos C, Pilliar RM, Smith DC. Threaded versus porous-surfaced designs for implant stabilization in bone-endodontic implant model. J Biomed Mater Res 1986;20:1309–1333.
2. Szmukler-Moncler S, Salama H, Reingewirtz Y, Dubruille JH. Timing of loading and effect of micromotion on bone-dental implant interface: review of experimental literature. J Biomed Mater Res 1998;43:192–203.
3. Pilliar RM, Lee JM, Maniatopoulos C. Observations on the effect of movement on bone ingrowth into porous-surfaced implants. Clin Orthop Relat Res 1986;208:108–113.
4. Frost HM. Wolff's law and bone's structural adaptation to mechanical usage: an overview for clinicians. Angle Orthod 1994;64:175–188.
5. Frost HM. Bone's mechanostat: a 2003 update. Anat Rec A Discov Mol Cell Evol Biol 2003;275:1081–1101.
6. Rubin CT, Lanyon LE. Regulation of bone mass by mechanical strain magnitude. Calcif Tissue Int 1985;37:411–417.
7. Duyck J, Ronold HJ, Van Oosterwyck H, Naert I, Vander Sorten J, Ellingsen JE. The influence of static and dynamic loading on marginal bone reactions around osseointegrated implants: an animal experimental study. Clin Oral Implants Res 2001;12:207–218.
8. Motoyoshi M, Yano S, Tsuruoka T, Shimizu N. Biomechanical effect of abutment on stability of orthodontic mini-implant. A finite element analysis. Clin Oral Implants Res 2005;16:480–485.
9. Meyer U, Vollmer D, Runte C, Bourauel C, Joos U. Bone loading pattern around implants in average and atrophic edentulous maxillae: a finite-element analysis. J Maxillofac Surg 2001;29:100–105.
10. Meyer U, Joos U, Mythili J, Stamm T, Hohoff A, Fillies T, et al. Ultrastructural characterization of the implant/bone interface of immediately loaded dental implants. Biomaterials 2004;25:1959–1967.
11. Tada S, Stegaroiu R, Kitamura E, Miyakawa O, Kusakari H. Influence of implant design and bone quality on stress/strain distribution in bone around implants: a 3-dimensional finite element analysis. Int J Oral Maxillofac Implants 2003;18:357–368.
12. Petrie CS, Williams JL. Comparative evaluation of implant designs: influence of diameter, length, and taper on strains in the alveolar crest. A three-dimensional finite-element analysis. Clin Oral Implants Res 2005;16:486–494.
13. Clelland NL, Gilat A. The effect of abutment angulation on stress transfer for an implant. J Prosthodont 1992;1:24–28.
14. Chun HJ, Shin HS, Han CH, Lee SH. Influence of implant abutment type on stress distribution in bone under various loading conditions using finite element analysis. Int J Oral Maxillofac Implants 2006;21:195–202.
15. Holmes DC, Loftus JT. Influence of bone quality on stress distribution for endosseous implants. J Oral Implantol 1997;23:104–111.
16. Kitagawa T, Tanimoto Y, Nemoto K, Aida M. Influence of cortical bone quality on stress distribution in bone around dental implant. Dent Mater J 2005;24:219–224.
17. Sevimay M, Turhan F, Kilicarslan MA, Eskitascioglu G. Three-dimensional finite element analysis of the effect of different bone quality on stress distribution in an implant-supported crown. J Prosthet Dent 2005;93:227–234.
18. Hansson S, Werke M. The implant thread as a retention element in cortical bone: the effect of thread size and thread profile: a finite element study. J Biomech 2003;36:1247–1258.
19. Isidor F. Loss of osseointegration caused by occlusal load of oral implants. A clinical and radiographic study in monkeys. Clin Oral Implants Res 1996;7:143–152.
20. Dalstra M, Cattaneo PM, Melson B. Load transfer of miniscrews for orthodontic anchorage. Orthod 2004;1:53–62.
21. De Smet E, Jaecques SV, Jansen JJ, Walboomers F, Vander Sloten J, Naert IE. Effect of constant strain rate, composed of varying amplitude and frequency, of early loading on peri-implant bone (re)modelling. J Clin Periodontol 2007;34:618–624.
22. Sugiura T, Horiuchi K, Sugimura M, Tsutsumi S. Evaluation of threshold stress for bone resorption around screws based on in vivo strain measurement of miniplate. J Musculoskelet Neuronal Interact 2000;1:165–170.
23. Yu WJ, Kyung HM. A quantitative evaluation of cortical bone stresses influenced by diameter of orthodontic micro-implant. J Korean Res Soc Dent Mater 2007;34:75–87.
24. Motoyoshi M, Hirabayashi M, Uemura M, Shimizu N. Recommended placement torque when tightening an orthodontic mini-implant. Clin Oral Implants Res 2006;17:109–114.
25. Cha JY, Yoon TM, Hwang CJ. Insertion and removal torques according to orthodontic mini-screw design. Korean J Orthod 2008;38:5–12.
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