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Enamel hypocalcification is a defect of tooth enamel in which normal amounts of enamel are produced but are hypomineralized. [ 1 ] [ 2 ] In this defect the enamel is softer than normal. Some areas in enamel are hypocalcified: enamel spindles, enamel tufts, and enamel lamellae.
Lamellae are linear enamel defects that extend from the surface of the enamel towards the DEJ, or vice versa. Enamel tufts are "small, branching defects that are found only at the DEJ, protruding into the enamel towards the enamel surface. Enamel spindles however, are in fact odontoblast processes that extend into the enamel. [1] [2]
Enamel tufts are small branching defects that are found only at the DEJ, and so differ from lamellae which can be facing either direction and are strictly linear. Enamel spindles are also linear defects, but they too can be found only at the DEJ, because they are formed by entrapment of odontoblast processes between ameloblasts prior to and ...
Hypomineralization or hypocalcification, as opposed to hypoplasia, refers to a decrease in the mineral content of the enamel, not the total amount present. It can vary in its presentation, and teeth may appear visually normal or highly translucent. Affected enamel is softer and more susceptible to acid, wear and decay.
Enamel tufts should also not be confused with the similar enamel spindles. Enamel spindles are also linear defects, similar to lamellae, but they too can be found only at the dentinoenamel junction, similar to enamel tufts. This is because they are formed by entrapment of odontoblast processes between ameloblasts prior to and during amelogenesis.
In primates enamel spindles were observed where the odontoblast process reaches until the border between dentin and enamel. With the discovery of TRPC5 as cold transducer the odontoblast transduction theory has become a likely explanation of dentinal hypersensivity [ 6 ]
Cutting speed may be defined as the rate at the workpiece surface, irrespective of the machining operation used. A cutting speed for mild steel of 100 ft/min is the same whether it is the speed of the cutter passing over the workpiece, such as in a turning operation, or the speed of the cutter moving past a workpiece, such as in a milling operation.
Tomes's processes (also called Tomes processes) are a histologic landmark identified on an ameloblast, cells involved in the production of tooth enamel. During the synthesis of enamel, the ameloblast moves away from the enamel , forming a projection surrounded by the developing enamel.