Abstract
A literature review points out a large discrepancy in the results of the mechanical tests on dentin that can be explained by stress and strain assessment during the tests. Errors in these assessments during mechanical tests can lead to inaccurate estimation of the mechanical properties of the tested material. On top of that, using the beam theory to analyze the bending test for thick specimens will increase these experimental errors. After summarizing the results of mechanical tests on dentin in the literature, we focus on bending tests and compare the stress assessment obtained by finite element analysis (FEA) and by beam theory application. We show that the difference between the two methods can be quite large in some cases, leading us to prefer the use of FEA to assess stresses. We then propose a new method based on coupling finite element analysis and digital image correlation (DIC) to more accurately evaluate stress distributions, strain distributions and elastic modulus in the case of a three-point bending test. To illustrate and prove the feasibility of the method, it is applied on a dentinal sample so that mean elastic modulus and maximum tensile stress are obtained (11.9 GPa and 143.9 MPa). Note that the main purpose of this study is to focus on the method itself, and not to provide new mechanical values for dentin. When used in standard mechanical testing of dentin, this kind of method should help to narrow the range of obtained mechanical properties values.
Highlights
Dentin is the main mineralized biological tissue of the tooth
With the maximum boundary load of 65 N found in the experiment, the stress distribution map is obtained by Finite Element Analysis (FEA) with beam dimensions corresponding to our dentin sample
Errors in stress and strain assessment during mechanical tests can possibly lead to a misevaluation of the mechanical properties
Summary
Dentin is the main mineralized biological tissue of the tooth It is located between the enamel and the pulp cavity and shows a hierarchical and complex structure at different scales. At the nanoscale, it consists of a carbonated nanocrystalline apatite mineral phase (approximately 50% by volume), a grid work of type I collagen fibrils (approximately 30% by volume) and fluids (approximately 20% by volume) [1]. Dentin can be seen as a continuous fiber-reinforced composite with peritubular cuffs as reinforcement and a matrix of intertubular dentin. At the macroscale, it can be seen as a bulk material with effective properties resulting from its complex structure. Dentin mechanical properties assessment is important in order to improve its restoration and to realize more biomimetic restorative materials
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