Abstract
In this work two very simple apparatuses, namely the ball crater (or ball-on-plate) and the linear reciprocating (or pin-on-plate) tests, were used in order to investigate the wear mechanisms of TPH Spectrum® and Resilab Master® dental composite resins. Loads in the range of 100 g to 1 kg and a total number of up to 24000 cycles were employed. During some of these tests, aqueous aluminum oxide suspensions were used as abrasive agent either diluted or not in distilled water. In case of the ball-on-plate test wear is dominated by abrasive and/or adhesive mechanisms, and is characterized by scratches which are composed of wear defects comprising particle detachment, wear of the polymer matrix and ceramic particle abrasion. However, the relative contributions of the two wear mechanisms could not be determined separately. In case of the pin-on-plate test wear is governed by the fatigue mechanism, although abrasive and adhesive wear mechanism are also present. After a certain number of cycles fatigue wear dominates the wear behavior and results in severe material loss. This mechanism seems to be more important in case of more brittle materials and when higher loads are employed. Qualitative analysis of the results suggests that the combination of these two very simple methods under appropriate conditions can yield sound results which may be representative of a number of clinical situations.
Highlights
Wear in the oral cavity is a complex phenomenon which depends on numerous factors
The results show that under certain conditions the ball-on-plate (BoP) wear test can be very useful for the study of wear governed by abrasive and/or adhesive mechanisms, while the pin-on-plate (PoP) wear test can be successfully employed in the study of wear governed by the fatigue mechanism
The wear scars appear as brighter regions parallel to the sliding direction that result from the removal of the polymeric matrix and ceramic particles
Summary
From a strictly tribological point of view, the term wear applies to the loss of material that result from the mechanical contact and relative movement of two bodies in the presence or not of a third body or medium. There are several (tribological) wear mechanisms described in the literature: abrasive, adhesive, fatigue, impact, corrosive and so on[1,2]. Abrasive wear occurs when a hard surface slides over a softer surface and damage it by plastic deformation or fracture. Adhesive wear occurs between two materials when the surfaces adhere and the shear action results in detachment of fragments of one material and attachment to the other one. Fatigue wear results from the repeated sliding or rolling of one surface over the other. Impact wear takes place when two surfaces collide with each other while having large
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