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20 Cards in this Set

  • Front
  • Back
Why is enamel the hardest substance in the body?
because of the number and arrangement of hydroxyapatite crystals
How are fluorapatite crystals made?
Fluoride replaces OH of CaOH forming the more insoluble fluorapatite crystal
what is amelogenin secreted by?
ameloblasts, odontoblasts and cementoblasts
Appear as small nanospheres that control spacing of hydroxyapatite crystal
May determine how wide and thick each crystallite will become (keeps the crystals thin)
Amelogenin
Found in surface layers of enamel (rod sheath)
Control saturation of enamel fluid
Maintain the sheath space as an escape route of enamel proteins
Prevent growth of interrod (tail) crystals into rod (head)
Ameloblastin
Present only at the mineralization front directly beneath the secretory face of Tomes’ process
Involved in crystal elongation and shape
By binding to sides of crystallites, inhibits growth in thickness and width
Enamelin

also noteand another thing that may be important to know is that enamelin is associated with hypoplastic amelogenesis imprefecta and kallikrein with hypomaturation AI
What is the difference between interrod substance and the rod?
the orientation of the hydroxyapatite crystals
Hypomineralized sheath surrounding each enamel rod
Allows etching of teeth for sealants
Rod Sheath
twisted rods of enamel under the cuspal tips that provide greater strength against forces of mastication
gnarled enamel
Concentric dark bands that follow the contour of the tooth surface
Hypomineralized areas of rods resulting from several days of growth during physiological stress such as sickness (hypomineralized so they show up darker)
Striae of Retzius
Accentuated hypomineralized line associated with child birth (large Striae of Retzius due to child birth)
neonatal line
Where will the neonatal line be found?
All primary teeth and first molars of the secondary teeth (teeth being formed during child birth)
Viewed only with reflected light
Alternating light & dark bands
Results from the arrangement of hydroxyapatite crystals
Hunter-Schreger Bands
Fusion lines between 2 growth centers of cusps
Fissure
Area where 2 fissures cross
Pit
Clinical significance of pits and fissures?
Enamel over pits and fissures is thin & less protective
Horizontal grooves on the surface of the tooth
Surface manifestations of the striae of Retzius
Termination of striae of Retzius
Perikymata
Appear as dark lines extending from the DEJ to the surface
Hypomineralized
Weak area of resistance to organic acids
Represents cracks in the enamel due to stress
Enamel Lamellae
Appear like tufts of grass
Hypomineralized
These are also more resistant to organic acids
Represents optical effect caused by the movement of ameloblasts from the DEJ
enamel tufts
Odontoblast cell processes which have crossed the DEJ – odontoblast, so these are not from the enamel – these are from the dentin
Surrounded by enamel – this forms when dentin & enamel are forming – cannot form after formation is complete
Believed to be responsible for the sensitivity of the tooth near the DEJ
enamel spindles