Enamel Flashcards
Enamel
most calcified tissue in the body, semipermeable, NOT STATIC and non-vital
mostly hydroxyapatite crystals
What secretes the enamel matrix?
Tome’s process, 1 rod for 1 process
Is Tome’s process a true process?
NO
What is an enamel rod?
functional unit of enamel, aka prism
enamel made of millions of rods
enamel is what kind of product?
ectodermal/epithelium
Describe the makeup of enamel
from IEE of enamel organ, NO
collagen product, contains ameleogins (controls growth and organization of crystals)
Where is the enamel matrix first formed?
incisal/occlusal part of crown near DEJ, moves to future outer enamel surface
When does the enamel matrix mineralize to fully matured?
apposition and maturation stages of tooth development
mineralization continues after eruption of tooth due to deposition of minerals such as fluoride and calcium
Gubernacular canal
ameloblasts becomes part of REE and create this canal for enamel cusps tip to erupt through, then tissue disintegrates
Keyhole effect
each rod has head and tail end
Crystals in head
parallel
Crystals in tail
starts to diverge, increase masticatory strength
ameleoblasts and Tome’s process affect crystal pattern
Where are rods thickest?
near cusp or incisal
Hunter-Schreger Bands
curved rods due to movement of ameloblasts during enamel production, dark or light colored bands
Interprasmatic/Interrod
associated with Tome’s process, different crystalline orientation, rod sheath less mineralized
DEJ
scalloped, formed by basement membraned, concavity faces dentin, convexity faces enamel
Lines of Retizus
incremental lines, bands of enamel rods like growth rings of tree
raised=perikymata*
lost through tooth wear
Lamellae
uncalcified vertical sheets of organic material, entire width of enamel, eventually worn down, narrower and longer than tufts
Enamel spindles
defects at DEJ, more prone to caries, extension of odontoblasts process of dentin into enamel
Enamel tufts
defect of calcification, appear as bundles of small dark brushes, hypo calcification of enamel prisms
What does the prism arrangement do?
gives direction to path of penetration for dental caries
Smooth surface caries
straight line direction
Which type of fluoride can cause fluorosis, topical or systemic?
systemic (during mineralization phase)
Acid etching
structure of enamel allows acid to penetrate surface and leave a rough surface, allows bonding materials to adhere more easily
Cavity preparation
it is important that unsupported enamel prisms are not left when removing decay and prepping cavities
Tetracycline staining
if taken during mineralization phase, most notable stains in dentin, darkest near cervix
Pits and fissures
less calcified area, more susceptible to caries, ameloblast become crowded between cusps and die forming weak spots, cuts off nutritional source
