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37 Cards in this Set

  • Front
  • Back
Enamel
Acellular and Avascular
96% inorganic 4% water
Thin near junction and Root
hard and brittle
most highly mineralized tissue in body
Cells of the inner enamel epithelium differentiate into
ameloblasts
Tomes process
-Shovel shaped
-responsible for the orientation of the enamel rod
What shape are ameloblasts in a cross-section?
Hexagonal
Formation of enamel?
Amelogenesis
2 Stages of Amelogenesis?
1 Secretory
2 Resorbing
Secretory Stage
deposition of enamel matrix that contains both organic and inorganic material
Resorbing stage
Removal by ameloblasts of most of the water and the organic matter
Enamel rods
Interlocking rods that help resist masticatory forces to prevent fracture between rods
Rod Sheath
Formed by a change in the angulation of the crystals formed by the ameloblasts as they move
*Outline around the periphery of the rod, especially noticable in the head region of the rod
Rod Sheath resists______more than Rod core.
demineralization
Enamel rods extend from the DEJ to ?
outer enamel surface-appear wavy due to the path of ameloblasts as they migrate
Enamel rods are _____shape?
keyhole
One rod is formed by?
4 different ameloblasts
hunter-schreger bands
alternating light and dark bands in the enamel due to configuration of the enamel rods
Rodless enamel
found on all deciduous teeth and 70% of the permanent teeth
-found at the cervical area of enamel
-less frequently found over the cusp tips
-structureless layer of enamel about 30 microns thick
gnarled enamel
*formed by enamel rods that have bent in exaggerated ways

*found near the dej over areas of the cusp tips
Enamel is unable to
remodel or repair
amelogenesis occurs during which stage of tooth development?
Late Bell Stage
incremental lines
a result of rhythmic deposition of enamel
3 types of incremental lines?
1 cross striations
2 striae retzius
3 neonatal line
Perikymata
small ridges on the tooth surface
cross striations
daily apposition lines
striae of retzius
more prominent growth lines may reflect major interruptions in deposition of enamel
neonatal
a significant striae of retzius
distinguishes prenatal enamel from postnatal enamel
Enamel spindle
single extension of dentinal tubules into the enamel
*shorter than tufts*
Enamel tufts
hypomineralized inner ends of some enamel rods
*defect in enamel*Bigger than spindle
Enamel lamellae
cracks in the surface of the enamel visible to the eye
*extend from the DEJ to the surface of the enamel
*possible pathway for dental caries to spread
no greater chance for fracture/ is greater risk for caries
Tetracycline Stain
Appear as dark bands through the enamel especially near the cervix of the tooth
*Does not affect enamel
*Binds to dentin and bone
*cannot bleach/caused by dentin
*Darkend dentin that shows through translucent enamel, giving tooth a darker appearance
2 functions of cementum
1Seals the tubules of root dentin
2 serves as attachment for periodontal fibers to suspend tooth in the socket
Cementum is
*less mineralized than enamel and dentin
*continues to grow throughout life
*thinnest near the cervix
*thickest at the apex
*no nerves
*not sensitive
_______is SHiny; _______is not shiny
Enamel; cementum
Bone
Vascular
nerves
lacunae cells
canaliculi
incremental lines
Cementum
avascular
no nerves
lacunae cells
canaliculi
incremental lines
more resistant to resorption and demineralization than bone
Hertwigs epithelial root sheath is formed by______
joining of OEE and IEE
Hertwigs epithelial root sheath degenerates and the remnants are called?
epithelial rests of mallasez
Cells from the _____________differentiate into cementoblasts?
dental follicle