La stabilité d'un implant dépend des propriétés biomécaniques de l'os à son contact. L'objectif de cette étude est de déterminer les propriétés biomécaniques de l'os néoformé pour différents temps de cicatrisation. Un modèle animal permettant de suivre la néoformation osseuse à l'interface a été développé. Des mesures par nanoindentation ont été réalisées dans des échantillons d'os cortical néoformé (4 et 7 semaines) et dans l'os mature en parallèle d'études histologiques. Le module d'Young moyen obtenu pour un temps de cicatrisation de 4 et 7 semaines est égal à 14.8 GPa et 16.1 GPa

ANAGNOSTOU, Fani

BARTHEL, Etienne

HAIAT, Guillaume

MATHIEU, Vincent

SOFFER, Emmanuel

VAYRON, Romain

I-Revues

20ème Congrès Français de Mécanique                                                                  Besançon, 29 août au 2 septembre 2011 
  1 
Variation des propriétés biomécanique de l’os néoformé 
déterminées par nanoindentation en fonction du temps de 
cicatrisation  
Romain VAYRONa, Etienne BARTHELb, Vincent MATHIEUc, Emmanuel SOFFERc, Fani ANAGNOSTOUc, 
Guillaume HAIATa 
aUniversité Paris-Est, Modélisation et Simulation Multi Echelle, MSME UMR CNRS 8208, 61, avenue du 
Général de Gaulle, 94010 Créteil, Cedex, France 
bCNRS, Laboratoire Saint Gobain, Surface du Verre et Interfaces, SVI UMR 125 CNRS/Saint-Gobain, 39, 
quai Lucien Lefranc, 93303 Aubervilliers, Cedex, FRANCE 
cCNRS, Laboratoire de Recherches Orthopédiques, Université Paris 7, B2OA UMR CNRS 7052, 10, avenue 
de Verdun, 75010 Paris, France 
Résumé :  
Les implants en Titane sont utilisés de manière quotidienne en implantologie clinique et leur développement 
a permis des progrès en chirurgie dentaire et orthopédique. Après une intervention chirurgicale, un 
phénomène de remodelage osseux se produit naturellement conduisant à la formation d’os néo formé afin 
d’assimiler l’implant. Les propriétés mécaniques du tissu osseux situé à 100-200 µm de la surface de 
l’implant, sont déterminantes pour la qualité de l’ostéointégration et de la stabilité de la prothèse. 
 
La stabilité d’un implant dépend des propriétés biomécaniques de l’os à son contact. L’objectif de cette 
étude est de déterminer les propriétés biomécaniques de l'os néoformé à différents temps de cicatrisation. Un 
modèle animal (tibia de lapin) permettant de distinguer l’os néoformé de l’os mature a été développé. Des 
mesures par nanoindentation ont été réalisées dans des échantillons d’os cortical néoformé (4 et 7 semaines) 
et dans l’os mature en parallèle d’études histologiques. Le module d’Young moyen obtenu pour un temps de 
cicatrisation de 4 et 7 semaines est égal à 14.80 GPa et 16.08 GPa et tend à retrouver les propriétés 
mécaniques de l’os mature (20.42 GPa). 
Abstract : 
Titanium implants are now routinely used clinically and their development have allowed considerable 
progresses in dental and orthopedic surgery. After a surgical intervention, remodeling phenomena normally 
occur, leading to the creation of newly formed bone tissue in order to accommodate the implant. The 
mechanical properties of bone tissue located at approximately 100-200 μm from the implant surface are 
determinant for the quality of osseointegration and the implant stability. 
 
The aim of this study is to determine the biomechanical properties of the newly formed bone tissue at 
different healing time. A rabbit tibia model to distinguish the new formed bone tissue from mature bone 
tissue was developed. Nanoindentation measurements were performed in samples of cortical newly formed 
bone tissue (4 and 7 weeks) and mature bone tissue in parallel histological studies. The obtained Young's 
modulus average for a healing time of 4 and 7 weeks is equal to 14.80 GPa and 16.08 Gpa and tend toward 
mature bone properties (20.42 GPa). 
Mots clefs : Bone ; Implant ; Osseointegration ; Nanoindentation Measurements; Mechanical 
Proper ties 
20ème Congrès Français de Mécanique                                                                  Besançon, 29 août au 2 septembre 2011 
  2 
1 Introduction  
Titanium implants are now routinely used clinically and their development have allowed considerable 
progresses in dental and orthopedic surgery. After a surgical intervention, remodeling phenomena normally 
occur, leading to the creation of newly formed bone tissue in order to accommodate the implant. The 
mechanical properties of bone tissue located at approximately 100-200 μm from the implant surface are 
determinant for the quality of osseointegration [1, 2]. A better understanding and characterization of the 
evolution of biomechanical properties of bone tissue at the microscopic scale may lead to more accurate 
prediction of implant osseointegration [3]. Such microscopic measurements can be done using different 
techniques. Scanning Acoustic Microscopy (SAM) has been used to assess bone acoustical properties in vitro 
with a resolution of around 30-60 μm [4]. More recently, a study published by our group [5] used a micro-
Brillouin scattering technique to characterize the elastic properties of newly formed bone tissue. 
Nanoindentation is also likely to be used to retrieve hardness and Young’s modulus at the microscopic scale. 
The aim of this paper is to investigate the biomechanical properties of newly formed bone in the vicinity of 
an implant using nanoindentation. 
2 Mater ial et methods 
2.1 Implant 
Two Titanium coin-shaped implants (5 mm ± 0.05 mm in diameter and 3 mm ± 0.05 mm in height) were 
used as described in details in [5]. These cylinders are made of medical grade titanium alloy (Ti-6Al-4V) and 
have their surfaces blasted with titanium dioxide (TiO2) particles, leading to an average Ra value of 1.9 μm 
for the implant surface roughness. Polytetrafluoroethylene (PTFE) caps were placed around the implant in 
order to create a gap of 200 µm in height between cortical bone surface and the implant (see Fig. 1), 200 µm 
corresponding approximately to typical values obtained in vivo [6]. The gap of 200 µm allows bone 
formation to occur in a cylindrical volume (bone chamber 200 µm thick, 4.2 mm of diameter) and enables a 
clear separation between mature and newly formed bone tissue, which can be seen in histological analysis 
(see Figure 1). The implants were placed in vivo on rabbit tibia levelled cortical bone surface.Sous-sous-
section (comme section) 
 
FIG. 1 Schematic representation of the coin-shaped implant model 
2.2 Rabbit model 
Two female New Zealand white rabbits were used in this study. The first rabbit was euthanized at 4 weeks 
(rabbit #1) post implantation and the second was sacrificed at 7 weeks (rabbit #2). The implanted tibiae were 
removed, prepared for histological analysis and cut perpendicularly to the implant interface. The procedure 
described in details in [7] for non-decalcified histology was used (samples embedded in PMMA).  
2.3 Nanoindentation measurements 
20ème Congrès Français de Mécanique                                                                  Besançon, 29 août au 2 septembre 2011 
  3 
Nanoindentation was performed in mature and newly formed bone tissue using a nano indenter XP (MTS 
System Corp., Oak Ridge, TN) with a Berkovich tip and the continuous stiffness measurement (CSM) 
method [8]. The calibration of the nanoindenter geometry was performed with a fused silica sample. For 
each sample, indents were realized in mature and newly formed bone tissue. In rabbit #1, 132 (respectively 
106) indents were realized in mature (respectively newly formed) bone tissue. In rabbit #2, 70 (respectively 
64) indents were realized in mature (respectively newly formed) bone tissue. The locations where the indents 
(3 µm of maximal penetration) were realized are separated by a distance of 30 μm. 
2.4 Statistical analysis 
Statistical analysis (ANOVA test and Tuckey-Kramer analysis) were performed to investigate the difference 
of Young’s modulus and hardness between samples for the different healing times. Statistical tests were 
performed using the Matlab software. 
3 Results and discussion 
Table 1 shows the difference in the averaged biomechanical properties between i) 4 weeks old bone tissue, ii) 
7 weeks old bone tissue and iii) mature bone tissue.  
 Newly formed bone 4 weeks 
Newly formed 
bone 7 weeks Mature bone 
E_harm (GPa) 14,80 (±0.95) 16,08 (±0.85) 20,42 (±0.98) 
H_harm (GPa) 0,61 (±0.05) 0,67 (±0.06) 0,68 (±0.06) 
Table 1 Averaging results of the study 
ANOVA (p=5.61*10-46, F=145.71) test reveals a significant effect of healing time on the Young’s modulus 
of bone tissue. For hardness, the results are similar (p=3.04*10-2, F=3.54). A Tuckey-Kramer analysis 
revealed that the Young’s modulus and Hardness values of newly formed bone tissue (4 weeks) were 
significantly different from those of mature bone tissue.  
The results (Hardness, Young’s modulus) obtained in this study are within the order of magnitude of results 
obtained in the literature. The difference of coloration in histological slide reveals a difference of 
mineralization between mature and newly formed bone, which may explain the difference in mechanical 
properties [9]. At four weeks, bone is less mineralized than after seven weeks of healing time. Biomechanical 
properties evolve during mineralization and tend toward mature bone properties. 
4 Conclusions 
A nanoindentation device was used to measure the Young’s modulus and Hardness in mature and newly 
formed bone tissue, showing a significant effect of healing time. This study gives further insight on the 
evolution of biomechanical properties of newly formed bone tissue at the micrometer scale as a function of 
healing time. The results might lead to a better understanding of the clinical evolution of titanium implant. 
References 
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[2] Mathieu, V., et al., Ultrasonic evaluation of dental implant biomechanical stability: an in vitro study. 
Ultrasound in Med. & Biol, 2010. 37(2): p. 262–270.  
[3] Winter, W., et al. A time-dependent healing function for immediate loaded implants. Journal of 
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[4] Meunier, A., et al., A reflection scanning acoustic microscope for bone and bone-biomaterials interface 
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20ème Congrès Français de Mécanique                                                                  Besançon, 29 août au 2 septembre 2011 
  4 
[5] Mathieu, V., et al. Micro-Brillouin Scattering Measurements in Mature and Newly Formed Bone Tissue 
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[8] Soffer, E., et al., Effects of autologous platelet lysates on ceramic particle resorption and new bone 
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Variation des propriétés biomécaniques de l'os néoformé déterminées par nanoindentation en fonction du temps de cicatrisation

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Variation des propriétés biomécaniques de l'os néoformé déterminées par nanoindentation en fonction du temps de cicatrisation

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