HISTOLOGY OF ENAMEL

Presented by: N. Robinson(CRRI)

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INTRODUCTION Enamel is a higly mineralised structure covering the anatomic crown of tooth. It is the only tissue that is totally acellular.PHYSICAL PROPERTIES: Colour:- appears bluish white or greyish at the thick opaque areas & yellow-white at the thin areas reflecting underlying dentin.

ENAMEL

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Hardness:- hardest structure of the body i.e.5 to 8khn.Permeability:- selectively permeable.Density:- decreases from the surface of enamel to the dentino-enamel junction.Thickness:- thickness over the cusps of the molars where it measures 2.5 mm & incisal edges of incisors where it is 2.0 mm.

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CHEMICAL PROPERTIESEnamel is composed of organic & inorganic substancesOrganic --------> 4%Inorganic--------> 96%Water

Enamel rods(prisms)Rod shealthsCementing inter-rod substance.STRUCTURE OF ENAMEL

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Enamel Rod Longitudinal section

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Wavy course of enamel rod Enamel rods followsa wavy course thefull thickness ofenamel A more spiral courseis noted at cusps &incisal areas Gnarled enamel

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Enamel Rod: Basic Structural Unit

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Cross section of enamel

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Microscopic picture of EnamelBrown striae ofRetzius

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DEJ, E tufts, E spindles

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Enamel lamellae & Cracks

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Perikymata (imbrication lines) Are external manifestationsof Retzius striae

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Development of Tooth

Tooth and Associated Structures

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