Term
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Definition
| Mineralized substance - hydroxyapatite |
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Term
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Definition
| organic material and water |
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Term
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Definition
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Term
| T/F Enamel is impermeable to water, ions, and some molecules? |
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Definition
| F. Enamel is permeable to water, ions and other moelcules |
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Term
| Color of enamel of newly erupted teeth? |
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Definition
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Term
| T/F The more translucent enamel is, the harder it is? |
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Definition
| True. Yellow hue is from dentiin, thus yellow teeth are strong |
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Term
| What manufactures enamel? |
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Definition
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Term
| What organic protein is used as the foundation for enamel? |
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Definition
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Term
| Collagen is present in enamel? |
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Definition
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Term
| Amelogenin is a collagen-like protein? |
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Definition
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Term
| Enamel is a vast bundle of these parallel units. |
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Definition
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Term
| Enamel rods are formed in units called? |
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Definition
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Term
| Structure of an enamel rod? |
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Definition
| Head, which makes enamel, and tail, which makes interrod enamel |
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Term
| In relation to one another, how are enamel rods spaced within the crown? |
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Definition
| Enamel rods are parallel to one another varying by as much as 10 degrees, but on avg 2 |
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Term
| Why is it important that enamel rods twist and turn from the DEJ to tooth surface? |
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Definition
| Prvent formation of cleavage planes. Reduces chance of fracture |
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Term
| An enamel rod resembles what shape? |
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Definition
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Term
| What happens to ameloblasts when they finish making enamel? |
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Definition
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Term
| Enamel can be renewed like dentin? |
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Definition
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Term
| How many ameloblasts comprise the head of an enamel rod? |
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Definition
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Term
| How many ameloblasts comprise the tail of an enamel rod? |
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Definition
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Term
| How man tails does each enamel head touch? |
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Definition
| The head touches 3 enamel tails -- 2 necks and one base |
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Term
| THe size of an enamel hydroxyapatite crystal? |
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Definition
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Term
| How are crystals arranged in the center of the enamel rod head and tail as well as the periphery ? |
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Definition
Head = parallel to long axis of rod
Tail = perpendicular to long axis of rod
Periphery - arranged in an oblique manner around long axis of rod |
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Term
| What are daily imbrication lines? |
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Definition
| Daily imbrication lines represent the diurnal rhythm of amelogenesis -- the amount of enamel deposited in one day. |
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Term
| What is the neonatal line? |
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Definition
Striae of retzius that forms during birth on crowns that are being developed at the time of birth.
It is more pronounced than common striae |
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Term
| T/F Neonatal line is a more pronounced striae of retzius? |
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Definition
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Term
| What exists between daily imbrication lines? |
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Definition
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Term
| What covers each enamel rod? |
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Definition
| Enamelin; insures organic portion is evenly distributed |
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Term
| What are striae of retizus? |
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Definition
| developmental disturbances recored in enamel. Areas of hypocalcified or normal enamel rods |
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Term
| When striae of retizus terminate at the tooth surface, what is formed? |
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Definition
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Term
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Definition
| shallow depressions on the tooth surface that are the result of striae of retizus terminating. |
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Term
| What are imbrication lines of pikerill? |
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Definition
| Elevations caused by perikymata |
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Term
| Why do striae of retzius appear to cross enamel rods? |
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Definition
| Because enamel rods are at different lenghts along the crown when trauma occurs |
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Term
| Why is the DEJ scalloped? |
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Definition
| Allow the convexity of enamel to fit into the concavity of dentin. Bring two different surfaces together |
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Term
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Definition
| hypocalcifed enamel rods that look like tufts of grass and extend 1/3 of the way into enamel from the DEJ |
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Term
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Definition
| Hypocalcifed or poorly calcifed enamel rods. Lamella does not pass through the DEJ |
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Term
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Definition
| Dentinal tubules stuck in enamel |
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Term
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Definition
| Cracks that penetrate the enamel and dentin. Passes through DEJ |
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Term
| Why is gnarled enamel important? |
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Definition
| Gives cusps more strength |
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Term
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Definition
| Enamel rods that twist around eachother from the DEJ to CUSP tip. |
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