Abstract
The extensive knowledge of root dentin’s mechanical properties is necessary for the prediction of microstructural alterations and the teeth’s deformations as well as their fracture behavior. Standardized microindentation tests were applied to apical, medial, and cervical root sections of a mandibular human first molar to determine the spatial distribution of the hard tissue’s properties (indentation modulus, indentation hardness, Martens hardness, indentation creep). Using an indentation mapping approach, the inhomogeneity of mechanical properties in longitudinal as well as in transversal directions were measured. As a result, the tooth showed strongly inhomogeneous material properties, which depended on the longitudinal and transversal positions. In the transversal cutting planes of the cervical, medial, apical sections, the properties showed a comparable distribution. A statistical evaluation revealed an indentation modulus between 12.2 GPa and 17.8 GPa, indentation hardness between 0.4 GPa and 0.64 GPa and an indentation creep between 8.6% and 10.7%. The established standardized method is a starting point for further investigations concerning the intensive description of the inhomogeneous mechanical properties of human dentin and other types of dentin.
Highlights
A human tooth consists mainly of dentin
Grzebieluch et al [2] modelled the mechanical properties of human dentin based on the concept of representative volume element (RVE) using the finite element method
The findings of the current study show that human root dentin has a highly inhomogeneous viscoelastic-plastic deformation behavior
Summary
A human tooth consists mainly of dentin. Extensive knowledge of the mechanical properties of dentin microstructure regarding dentin alterations (abrasive and erosive processes, sclerotic dentine) and the fracture behavior, as well as the interaction with bonding agents and restorative materials, is required. Kinney et al summarized the reliable ranges for the magnitudes of mechanical properties of human dentin, such as hardness, strength, fracture toughness, and fatigue, in a literature review [1]. For the modelling of the entire tooth, measurements of the mechanical properties are required. Grzebieluch et al [2] modelled the mechanical properties of human dentin based on the concept of representative volume element (RVE) using the finite element method. The authors used the elastic properties determined by Kinney et al [3] for the RVE modelling of dentin with a certain tubule orientation
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