DENTAL ANATOMY & HISTOLOGY

Physical Properties

• The enamel is the outermost layer of the tooth.
• Origin of the enamel cells is from the ectoderm and the cells producing enamel are known as ameloblasts.
• After the final steps of enamel formation the ameloblasts form a layer over the completed enamel surface. It is known as Nasmyth’s membrane or the Primary enamel cuticle.
• Thickness of the enamel at the incisal edges of anteriors is 2 mm.
• Thickness of the enamel at the cusps of the premolars is 2.3 – 2.5mm.
• Thickness of the enamel at the cusps of the molars is 2.5 – 3 mm.
• The outermost layer of the enamel is structureless and is 30 µm thick.
• The enamel is semitranslucent and the colour is actually that of the underlying dentin.
• It turns white when dried because of the loss of surface bound water.
• The enamel has high modulus of elasticity but very low tensile strength. This is the reason for its brittleness.
• Enamel surface shows grooves and fissures as a result of developmental fusion of the various lobes.
• Grooves are formed by the proper coalescence of the developmental lobes.
• Faulty coalescence produces fissures.
• The solubility of the enamel in acids increases from the surface towards the dentinoenamel junction.

Chemical Composition

• The enamel contains about 95 – 98% of inorganic matter by weight.
• The organic component constitutes about 1 – 2 % by weight.
• The water content of the enamel is about 4 % by weight.
• The enamel is basically comprised of hydroxyapatite crystals.