Tribological characterization of dental restorative materials

Abstract

Human teeth are exposed to a considerable amount of wear on a daily basis due to chemical and mechanical actions. To overcome the damage seen on natural teeth, the dental restorations have been widely used. Like teeth, the restorations are also submitted to shear stresses and, therefore, the evaluation of their tribological behaviour is essential. The aim of this study was to compare the wear behaviour of the main types of dental restorative materials used (polymers, composites and ceramics) under the same conditions. Among them was included a polychromatic feldspathic porcelain material which was selected to find out if the opacity or translucency influences the tribological behaviour of the material. The wear tests were performed in a reciprocating ball-on-plate tribometer under 37 °C using artificial saliva to mimic oral conditions as well as alumina balls as antagonists. Friction coefficient (COF) and specific wear rate values were determined, and SEM/EDS examinations were made to identify the dominant wear mechanisms. Results showed that zirconia exhibited the highest wear resistance, with an average value of specific wear rate of k = 1.63E-07 mm3N−1m−1, and this result was significantly different from that of other materials. Composite material presented the lowest wear resistance (k = 1.24E-05 mm3N−1m−1). The results indicated that the wear behaviour of ceramics can be affected by their optical properties, possibly associated with the crystal structure modifications. Specific wear rate and hardness have a statistically significant linear relationship. Zirconia revealed to be a potential material for constructing high wear-resistant dental restorations.