Enamel

    Cards (10)

    • Enamel Lamellae:
      • Thin leaf-like structures in enamel that extend from varying depths from the surface of enamel towards DEJ
      • Visible in ground sections of tooth, better in cross-section
      • Seen in carefully demineralized/ decalcified sections of human enamel due to higher organic content
      • Defects formed during enamel development, filled with organic material
    • Classification of enamel lamellae:
      • Type A: Group of poorly calcified enamel rods
      • Type B: Filled with odontogenic degenerated cells
      • Type C: Cracks filled with organic matter
      • Develop in lines of stress where calcification may be incomplete, becoming a site of weakness in enamel for bacterial entry
    • Formation of enamel lamellae:
      • Develop in lines of stress where calcification may be incomplete
    • Clinical significance of enamel lamellae:
      • Form a route for bacterial entry due to weakness in enamel
    • Differentiation between type C enamel lamellae and crack:
      • Use careful demineralization, crack disappears while lamella is retained due to higher organic content
    • Dentino-enamel junction (DEJ):
      • Junction between dentin and enamel, established during formation of dentin and enamel
      • Scalloped appearance, revealed as a series of ridges under scanning electron microscope
      • Ridging more pronounced in coronal region to prevent shearing of enamel during function
    • Enamel spindle:
      • Spindle-shaped structures seen in enamel at DEJ
      • Formed by developing odontoblast processes extending into ameloblasts layer before enamel formation
      • Demonstrated in ground sections, surrounded by interrod enamel
      • More spindles in incisal and cuspal regions, appear dark in transmitted light and lighter in reflected light
    • Formation of enamel spindles:
      • Developing odontoblast processes extend into ameloblasts layer before enamel formation
    • Gnarled enamel:
      • Structure seen at incisal edge or cusp tips, formed by intertwining of enamel rods
      • Arrangement withstands masticatory forces, formed due to irregular movement of ameloblasts during enamel deposition
    • Formation of gnarled enamel:
      • Irregular movement of ameloblasts during enamel deposition due to overcrowding
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