Evolution of bone biomechanical properties at the micrometer scale around titanium implant as a function of healing time

Abstract

The characterization of the biomechanical properties of newly formed bone tissue around implants is important to understand the osseointegration process. The objective of this study is to investigate the evolution of elastic properties of newly formed bone tissue as a function of healing time. To do so, nanoindentation and micro-Brillouin scattering techniques are coupled following a multimodality approach using histological analysis. Coin-shaped implants were placed in vivo at a distance of 200 µm from the cortical bone surface, leading to an initially empty cavity. Two rabbits were sacrificed after 7 and 13 weeks of healing time. The histological analyses allow us to distinguish mature and newly formed bone tissue. The bone mechanical properties were measured in mature and newly formed bone tissue. Analysis of variance and Tukey-Kramer tests reveals a significant effect of healing time on the indentation modulus and ultrasonic velocities of bone tissue. The results show that bone mass density increases by 12.2% (2.2% respectively) between newly formed bone at 7 weeks (13 weeks respectively) and mature bone. The dependence of bone properties on healing time may be explained by the evolution of bone microstructure and mineralization.

Reflection of an ultrasonic wave on the bone−implant interface: Effect of the roughness parameters

“…However, some discrepancies could explain the differences between experimental results and numerical predictions. First, the present study does not consider the changes of the bone material properties, which are known to occur during healing (Mathieu et al, 2011b;Vayron et al, 2012b;Vayron et al, 2014b) and which induce a concurrent increase of the reflection coefficient as a function of healing time (Vayron et al, 2016). Second, in the experimental configuration, the ultrasonic wave is not fully planar due to the use of a focused immersed transducer, which has not been considered in the present study.…”

“…Therefore, fullybonded interfaces are not likely to occur in vivo. Moreover, bone properties are known to vary during osseointegration (Mathieu et al, 2011b;Vayron et al, 2012b;Vayron et al, 2014b), which was not taken into account. Fourth, bone tissue was modeled as an elastic, homogeneous and isotropic material, similarly to what was done in some previous studies (Haïat et al, 2009;Mathieu et al, 2011a;Vayron et al, 2015;, whereas real bone tissue is known to be a strongly dispersive medium (Naili et al, 2008;Haiat and Naili, 2011).…”

“…Various techniques such as impact methods (Schulte et al, 1983;Van Scotter and Wilson, 1991 ;Mathieu et al, 2013;Michel et al, 2016) or resonance frequency analysis (Meredith et al, 1996;Georgiou and Cunningham, 2001;Pastrav et al, 2009) have been applied to investigate the BII properties. In an ex vivo study using a coin-shaped implant model (Vayron et al (2012a), the reflection coefficient of a 15 MHz ultrasonic wave interacting with the BII significantly decreases as a function of healing time, which may be explained by a decrease of the gap of acoustical properties at the BII related to a combined increase of i) the bone-implant contact (BIC) ratio, ii) the bone Young's modulus (Vayron et al, 2012a) and iii) bone mass density (Mathieu et al, 2011b;Vayron et al, 2014b). These results open new paths in the development of quantitative ultrasound (QUS) methods that had been previously suggested to assess dental implant stability (de Almeida et al (2007).…”

Stochastic multiscale modelling of cortical bone elasticity based on high-resolution imaging

“…Spatial variations of HP and TMD in the femoral hip region induce heterogeneity of cortical bone at the organ scale (Bensamoun et al 2004a, b;Yamato et al 2006;Sasso et al 2007Sasso et al , 2008Mathieu et al 2013). This heterogeneity strongly affects the mechanical response of bone as it was widely documented by studies on ultrasonic wave propagation (Haiat et al 2009(Haiat et al , 2011Naili et al 2010;Grimal et al 2014) and nanoindentation (Yao et al 2011;Vayron et al 2012Vayron et al , 2014.…”

Biomechanical behaviours of the bone–implant interface: a review

“…However, it was difficult to clearly distinguish between mature and newly formed bone tissue because both types of tissue were interconnected and difficult to clearly distinguish. In order to overcome the aforementioned limitation, we have implemented the implant model described in figure 5 in order to create a 200 µm thick bone chamber between mature bone and the implant surface [136][137][138]. The bone chamber was designed using PTFE layers, as shown in figure 5.…”