β Scribed by S.D. Heintze; G. Zellweger; G. Zappini
No coin nor oath required. For personal study only.
A wear method was developed that mainly simulates attrition wear using a commercially available chewing simulator (Willytec, Germany). In this test, a standardized stylus made of pressable ceramic (Empress) hits flat specimens 120,000 times with a 5 kg weight, a descent speed of 60 mm/s and a lateral movement of 0.7 mm with a speed of 40 mm/s under constant exchange of water at different temperatures (325 Γ 5 β’ C/55 β’ C). The volume loss was measured on plaster replicas with the Laserscan 3D (Willytec) and the Match 3D software. Twenty-four experimental and commercial composites (n = 8) were tested with a volumetric wear range of between 5.5 and 147 Γ 10 -2 mm 3 . On standardized specimens made of the same composites, the Vickers hardness (H), elastic modulus (E) and fracture toughness (K 1c ) were measured. The mean particle size (d) and volume content (v f ) of the inorganic filler were evaluated. Furthermore, a differentiation was made between the main filler with the largest mean size (d 1 , v f,1 ) and the total filler content (v f,tot ). Results: The best linear regression curve fit with an adjusted R 2 of 0.908 was found for
Conclusions: The good mathematical fit of the formula may be an indication that the wear method is based on physical properties and that it provides a highly reproducible standard.
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