enamel structure Flashcards
inorganic & organic percentages of enamel
96% inorganic mineral crystals
4% organic enamel proteins & water
NO COLLAGEN
how do rod crystals run in the enamel
perpendicular to the ADJ
throughout the full length of the enamel
where are interrods
surrounding each rod
what are enamel spindles
narrow tubules in enamel
extend up to 25mm
where do enamel spindles originate
from odontoblast processes embedded within enamel during development
role of enamel spindles?
may increase adherence between dentine and enamel
may have role in sensitivity - pain receptors?
what are enamel tufts
projections from ADJ
1/4 through enamel thickness
at regular intervals
thought to occur due to abrupt changes in rod direction
faults in enamel synthesiswhat are enamel lamellae
narrow long
run through entire thickness of enamel
clinical significance of enamel lamellae
increased caries risk
rich in organic material
gap in enamel layer - no enamel rod formed
what are incremental lines in enamel
changes in enamel secretory rhythm
what are cross striations
type of incremental line
daily lines
thinner - less enamel deposited
what are striae of retzius
type of incremental line
weekly rhythm
formed as a result of temporary constriction of tomes processes
create perikymata grooves at enamel surface
what are striae of retzius
type of incremental line
weekly rhythm
formed as a result of temporary constriction of tomes processes
create perikymata grooves at enamel surface
what are neonatal lines
enlarged striae of retzius
reflect physiological changes occuring at birth
present in all deciduous teeth and first premanent molars
what are hunter schreger bands
opitcal phenomenon- lighting
alternating bands of rods cut longitudinally and transversely
as ameloblasts deposit enamel in a sinusoudal patter
complex pattern makes enamel resistant to fracture
