The multi-scale meso-mechanics model of viscoelastic dentin

Yusen Chen; Rui Wu; Lulu Shen; Yabin Yang; Guannan Wang; Bo Yang

doi:10.1016/j.jmbbm.2022.105525

The multi-scale meso-mechanics model of viscoelastic dentin

J Mech Behav Biomed Mater. 2022 Dec:136:105525. doi: 10.1016/j.jmbbm.2022.105525. Epub 2022 Oct 20.

Authors

Yusen Chen¹, Rui Wu², Lulu Shen¹, Yabin Yang³, Guannan Wang⁴, Bo Yang⁵

Affiliations

¹ Department of Civil Engineering, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
² Department of Civil Engineering, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China; Center for Balance Architecture, Zhejiang University, Hangzhou, 310007, China.
³ School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China.
⁴ Department of Civil Engineering, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China; Center for Balance Architecture, Zhejiang University, Hangzhou, 310007, China. Electronic address: guannanwang@zju.edu.cn.
⁵ Department of Civil Engineering, Zhejiang Sci-Tech University, Hangzhou, 310018, China. Electronic address: youngbo@zstu.edu.cn.

PMID: 36302275
DOI: 10.1016/j.jmbbm.2022.105525

Abstract

Human dentin is a hierarchical material with multi-level micro-/nano-structures, consisting of tubule, perti-tubular dentin (PTD) and intertubular dentin (ITD) as the major constituents at microscale; and the PTD and ITD are further composed of collagen and hydroxyapatite (HAp) crystals with different volume fractions at nanoscale. In most cases, the HAp is considered as elastic while the collagen as viscoelastic material. It is of great significance to study the hierarchical structure and viscoelasticity of human dentin to understand the mechanical properties of dentin for further development of restorative materials. Based on this, this paper focuses on multiscale modeling of the elastic properties and dynamic viscoelastic response of dentin and establishes a bottom-up micromechanics model from nano-to macro-scale. In order to study the nanostructural effect on the viscoelastic behavior of hierarchical structures, the homogenization theories of random platelets composites (HTRPC) and the locally-exact homogenization theory (LEHT) are introduced for the homogenization of heterogeneous materials of microstructures at different levels. The HTRPC, based on Eshelby Inclusion theory, is used to predict the effective modulus of PTD and ITD. The LEHT is a method for homogenizing multiphase dentin characterized by repeated unit cells (RUCs). The resulting predictions are in very good agreement with several experimental data from the literature. In addition, the results of nanostructrual effect on dentin show that the viscoelasticity of dentin is majorly contributed by collagen and the HAp greatly provide the strength and hardness of dentin. Furthermore, the ageing effect on dentin's viscoelasticity is considered from the proposed multiscale micromechanics model. It is demonstrated that the ageing effect is much more influential in affecting the loss moduli of dentin than the storage.

Keywords: Dentin; Dynamic viscoelasticity; Hierarchical structure; Micromechanics and homogenization; Storage and loss moduli.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Collagen* / analysis
Dentin* / chemistry
Hardness
Humans

Substances

Collagen