Hardness and Wear Resistance of Dental Biomedical Nanomaterials in a Humid Environment with Non-Stationary Temperatures.

Daniel Pieniak,Krzysztof Przystupa,Mariusz Walczak,Agata Walczak,Agata M Niewczas

doi:10.3390/ma13051255

Abstract

This study discusses a quantitative fatigue evaluation of polymer–ceramic composites for dental restorations, i.e., commercial material (Filtek Z550) and experimental materials Ex-nano (G), Ex-flow (G). Their evaluation is based on the following descriptors: microhardness, scratch resistance, and sliding wear. In order to reflect factors of environmental degradation conditions, thermal fatigue was simulated with a special computer-controlled device performing algorithms of thermocycling. Specimens intended for the surface strength and wear tests underwent 104 hydrothermal fatigue cycles. Thermocycling was preceded by aging, which meant immersing the specimens in artificial saliva at 37 °C for 30 days. Microhardness tests were performed with the Vickers hardness test method. The scratch test was done with a Rockwell diamond cone indenter. Sliding ball-on-disc friction tests were performed against an alumina ball in the presence of artificial saliva. A direct positive correlation was found between thermocycling fatigue and microhardness. The dominant mechanism of the wear of the experimental composites after thermocycling is the removal of fragments of the materials in the form of flakes from the friction surface (spalling). Hydrothermal fatigue is synergistic with mechanical fatigue.

Highlights

Dental restorative materials are classified as resin-based composites (RBCs) [1]
Hardness assessment is widely used by RBCs researchers
The microhardness test allows for the assessment of the mechanical properties of the composite surface

Summary

Introduction

Dental restorative materials are classified as resin-based composites (RBCs) [1]. In the literature, they are often listed as light-cured polymer matrix ceramic composites (LC PMCCs). Because long-term degradation processes such as fatigue, wear, and caries often create a need to repair human teeth [2]. LC PMCCs are characterized by good performance. On the basis of the work [3], the failure of restorative composites may occur, among others, due to poor wear resistance. The inorganic phase is of key importance for the performance of resin composites. Its contribution to the structure of the composite, and its shape, type, and size are significant [4]

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