CSA histology of enamel and dentine caries Flashcards
What is enamel like?
- brittle so relies on dentine for resistance
What is enamel pure mineral like?
3% water, 1% protein (non-collagenous) and 96% HAP:
Where is enamel most thick?
incisal edge
What are HAP crystals ordered in ?
prism/rod runs from dentine (ADJ) to below tooth surface
-Approx. 5um in diameter
What are prisms like in longitudinal sections?
perp. to ADJ
What is enamel production like?
• Circadian rhythm in enamel production = , daily, cross-striations w/ 5um periodicity:
What are Striae of Retzius (brown incremental lines)
superimposed on 5um periodicity
o Towards cusp = irregularly spaced but more regular towards cervical margin
When are tuft proteins seen?
enamel crown = completely removed with acid (demineralised)
What is tuft protein ?
areas in between prisms where enamel proteins collected
When are tufts seen
transverse section
what are prisms in tufts like
- Prisms = change path at each level
- High protein content at prism boundaries = superimposed on each level
What are spindles?
odontoblast process crossing forming ADJ into developing enamel during crown development
Where do spindles originate ? ( cigar shape)
at ADJ into enamel
What are seen in longitudinal sections?
- Striae of Retzius
- Enamel Spindles (also see in thick transverse sections)
- Scalloped Nature of ADJ
- Gnarled Enamel
- Hunter-Schreger Bands
- Cross Striations of Enamel Prisms
What are striae of retzius?
Incremental growth lines = obliquely across prisms to
approach enamel surface
What are striae of retzius associated with at surface?
depressions called Perikymata
What does scalloping of ADJ do ?
aids retention of enamel to dentine + resists shearing forces (more irregular + incr. SA at point of contact between enamel/dentine)
What are enamel spindles?
- Continuous w/ dentinal tubules across ADJ
What are enamel spindles due to ?
odontoblast process crossing the forming ADJ into developing enamel during crown development which leaves a void
What is gnarled enamel ?
-Evolved to resist incr. loads and decr. shearing forces at cusps
What does gnarled enamel look like ?
- On sides of crown, prisms run in straight lines perp. (90 to ADJ)
- At cusp tip) prims = appear more disordered
What are cross striations?
Represent daily incremental growth lines + give prisms ladder appearance
What are HS bands?
Optical effects due to longitudinal sectioning of alternating paths of prisms
Where are HS bands only visible?
inner 2/3rds of enamel