Dental enamel Flashcards
Where is visible enamel?
crown of tooth= “clinical” crown
what is enamel?
White, hard that covers outside of tooth
what is the anatomical crown?
part of tooth completely covered in enamel
what are enamel features?
brittle
rely on dentine for strength
what happens to enamel with age?
thinner so more yellow dentine shows through more
what is the pure organic mineral in enamel?
Hydroxyapatite
what is organic material in enamel?
non collagenous proteins
where is enamel most thick?
incisal edge
What is spot process of caries?
white opaque spot> brown lesion stain> cavity
what does wedge shape cavity mean?
lesion reached dentine
why does lesion initially appear white?
sub surface enamel is porous
what is amelogenesis imperfecta?
enamel affected by genetic defects
what is HAP?
Ca10(P04)6(OH)2
How are HAP crystals arranged?
Prisms- from dentine to below tooth surface
how are prisms arranged in cross sec?
perpendicular to ADJ
What do prism have?
circadian rhythm for daily cross striations
what are imposed on daily cross striations of enamel?
Brown Striae of Retzius
What direction to prisms run from?
right to left
What is prism arrangement of Rat incisor ?
prism different to neighbour
What is prism arrangement in human enamel?
1) 2 groups run Longitudinal
2) Transverse- prism give key hole shape
What is type 1 enamel?
prisms= circular/hexagonal
what is type 3 enamel?
continuum between prisms and interprismatic enamel in row below so key hole shape
What is enamel structure at ADJ?
Tufts
spindles
lamellae
What is enamel structure not at ADJ?
hunter Schreger bands
gnarled enamel
perikymata
aprismatic enamel
