Experimental Investigations of the Dental Filling Materials: Establishing Elastic Moduli and Poisson’s Ratios

Abstract

The mechanical properties of the dental filling material (DFMs) strongly influence the lifetime and durability of the tooth reparation performed. Among the most significant mechanical characteristics, one has to mention the Poisson’s ratio and the elastic modulus (Young’s modulus). They, during the cyclic mastication load, can prevent or aid in the prevention of secondary dental decays by provoking micro-cracks, the de-bonding of the filling material from the natural dental tissue, as well as fatigue at the level of their interface. The authors performed a scoping analysis of the nowadays-involved experimental methods, together with a critical review, putting in evidence of their advantages and limits. Based on the developments, they propose a new approach in this sense by involving the electronic speckle pattern interferometry (ESPI)/shearography high-accuracy optical method. They illustrate the advantages of this method in establishment of the elastic modulus, but they also propose a high-accuracy methodology in the estimation of Poisson’s ratio. Based on the briefly-illustrated experimental results, one can conclude that ESPI/shearography can become a very useful tool for research, even though it is not a common (nowadays widely applied) method, such as three-point bending or strain gauge methods.

Highly Reinforced Acrylic Resins for Hard Tissue Engineering and Their Suitability to Be Additively Manufactured through Nozzle-Based Photo-Printing

“…Regarding tangent modulus values ( Figure 4 ), although the bilinear stress vs. strain behavior in compression of highly filled dental composites is largely documented [ 39 , 41 , 52 , 53 ] and consistent with the observed behavior (see Supplementary Files ), little attention has been given to the values of the tangent modulus occurring in the second linear stage of the stress vs. strain curves in compression. The tangent modulus value is of paramount importance for defining the elastic constitutive equation of the highly filled composite material to be used in finite element analysis simulations of a restored tooth or a medical device such as scaffolds and prostheses for mineralized tissue.…”

“…Stress vs. strain curves can be found in the Supplementary Files . The use of inorganic nanoparticles for increasing mechanical properties of restorative resins has gained great attention in the last decade, and compressive properties are of paramount importance because highly mineralized tissues in the oral cavity (i.e., dentin and bone) mainly undergo a compressive state of stress during mastication; crack initiation at restorative sites causes secondary caries [ 26 , 39 , 40 , 41 ].…”

“…In fact, if the compressive strain is evaluated through the cross-head displacement of the dynamometer [ 39 , 40 ], significantly lower Young’s modulus values are assessed. Instead, if the strain is measured through local deformation sensors [ 41 ], then higher Young’s modulus values are estimated [ 42 , 51 ]. In other words, the compliance of the dynamometric instrument has a large influence on the computation of the Young’s modulus.…”