44 research outputs found
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On the in vitro fatigue behavior of human dentin with implications for life prediction
Although human dentin is known to be susceptible to failure under repetitive cyclic fatigue loading, there are few reports in the literature that reliably quantify this phenomenon
Enamel-like apatite crown covering amorphous mineral in a crayfish mandible
Carbonated hydroxyapatite is the mineral found in vertebrate bones and teeth, whereas invertebrates utilize calcium carbonate in their mineralized organs. In particular, stable amorphous calcium carbonate is found in many crustaceans. Here we report on an unusual, crystalline enamel-like apatite layer found in the mandibles of the arthropod Cherax quadricarinatus (freshwater crayfish). Despite their very different thermodynamic stabilities, amorphous calcium carbonate, amorphous calcium phosphate, calcite and fluorapatite coexist in well-defined functional layers in close proximity within the mandible. The softer amorphous minerals are found primarily in the bulk of the mandible whereas apatite, the harder and less soluble mineral, forms a wear-resistant, enamel-like coating of the molar tooth. Our findings suggest a unique case of convergent evolution, where similar functional challenges of mastication led to independent developments of structurally and mechanically similar, apatite-based layers in the teeth of genetically remote phyla: vertebrates and crustaceans
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On the in vitro fracture toughness of human dentin
The in vitro fracture toughness of human dention has been reported to be of the order of 3 MPa sqrt m. This result, however is based on a single study for a single orientation, and furthermore involves notched, rather than fatigue precracked, test samples
Studio di leghe di piombo e stagno per il recupero e la conservazione di organi musicali
none5noneG.L.Garagnani; V.Imbeni; C.Martini; G.Poli; D.PrandstrallerGaragnani, Gian Luca; V., Imbeni; C., Martini; G., Poli; D., Prandstralle
Recommended from our members
On the in vitro fracture toughness of human dentin
The in vitro fracture toughness of human dention has been reported to be of the order of 3 MPa sqrt m. This result, however is based on a single study for a single orientation, and furthermore involves notched, rather than fatigue precracked, test samples