Structural Components of Teeth Flashcards
What is enamel formed by?
a. What is this process called?
Ameloblast
a. Amelogenesis
What part of the tooth does enamel protect?
Anatomical crown
What part of the enamel is the hardest?
a. The density of enamel increases from?
b. What part of the occlusal surface is the enamel the thickest?
Peripheral
a. DEJ to surface
b. Cusp tips
What color is enamel?
a. What is enamel called when it can be different colors?
Semi-translucent
a. Polychromatic (thinner = yellowish white, thicker = blue-grayish white)
Does enamel have high compressibility?
a. Tensile strength?
b. Shear strength?
Yes
a. Low
b. Low
What is enamel supported by?
Underlying dentin
What dissolved enamel?
a. What reduces the solubility and increases the hardness?
Acid (demineralization)
a. Fluoride
Is surface or deep enamel more soluble?
Deep
Is enamel permeable? How does water and ions pass through enamel?
Yes (selective), Osmosis
What is the chemical composition of enamel?
a. What is the inorganic content of enamel?
b. What does fluoride do to the inorganic component and what does it do?
Inorganic = 96%, organic = 1%, Water 3-4%
a. Hydroxyapatite
b. Fluoride with calcium (replace –OH) → fluoroapatite (harder)
What does what do to the enamel?
Hydrated shell or covering around apatite crystal
What is the fundamental unit of enamel?
a. What are their shapes?
b. Permanent enamel rods radiate in a __________________ to _______________? Towards what surface?
c. Primary rods are ____________________ to __________________?
- Enamel prisms (rods)
a. Keyhole, interlocking
b. Perpendicular form surface, DEJ
c. Perpendicular, DEJ
What are Lines of Retzius?
a. Wave-like surface characterization called?
Incremental growth lines (Enamel), concentric series, brown lines, arc-like, wave-like
a. Perikymata
Alternating light and dark bands of enamel rods (artifact of specimen sectioning)?
a. Dark bands?
b. Light Bands?
Hunter-schreger bands
a. Diazones
b. Parazones
What is the main component of teeth?
a. What is this formed by?
b. What is this process called?
Dentin
a. Odontoblast
b. Dentinogenesis
What microscopic tubules radiate outward from the pulp?
a. Are they thicker or thinner towards the pulp?
b. What are the extensions called?
c. What are they made of?
Dentin tubules
a. Thicker towards the pulp
b. Odontoblast processes
c. Odontoblast cells
What is the color of dentin?
Yellowish white
Is dentin permeable?
a. What happens with age?
Highly
a. Decreases
What property of dentin supports the brittle enamel?
Elastic
What is the chemical composition of dentin?
Inorganic = 75%, Organic = 20%, Water 5%
What inorganic composition of dentin acts as hydroxylapatite?
Calcium phosphate
Fluoride is how many times more prominent in dentin than enamel?
a. Is fluoride higher in primary or permanent teeth?
b. Is fluoride more concentrated towards pulp or surface enamel?
c. What happens in concentration of fluoride with age?
2-3 times
a. permanent
b. pulp
c. increase with age
What is the organic composition of dentin made of?
mostly collagen and some lipids (cholesterol)
Dentinal matrix
a. Peritubular dentin?
b. Intertubular dentin?
a. more mineralized
b. mainly collagenous fibers crisscrossing between tubules
Incremental lines of growth similar to Lines of Retzius (dentin)?
Lines of Owen (imbrication lines)
Demarcation between prenatal and postnatal dentin(in primary teeth and permanent first molars)?
Neonatal Lines
What is Primary dentin?
a. Secondary dentin?
b. Tertiary dentin?
c. Tubules obliterated by minerals?
d. Tubules with dead odontoblast processes?
Initial formation of tooth
a. Next to pulp, lifelong (Physiological secondary dentin)
b. Reaction to caries (Reparative secondary dentin)
c. Sclerotic dentin
d. Dead tracts
What is cementum made from?
a. What is this process called?
Cementoblasts
a. Cementogenesis
What is the color of cementum?
Light yellow
What is the chemical composition of cementum?
Inorganic = 50% (hydroxyapatite), Organic = 50%
What are the types of cementum?
Acellular = 2/3 cervical root (mainly calcified), cellular = apical 1/3 (mainly cementocytes, secondary cementum → result of trauma)
What is used to remove microscopic amounts of enamel hydroxyapatite in bonding?
Acid etching
____________________ flows into roughed crevices and bonds __________________
Resin, Mechanically
Is bonding to dentin simple or complex?
a. Why?
Complex because of collagen matrix (etching removes mineral components and a resin/collagen hybrid layer is formed into the dentinal tubules)
