Your SlideShare is downloading. ×
Enamel
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Enamel

5,519

Published on

0 Comments
4 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
5,519
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
296
Comments
0
Likes
4
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Enamel
  • 2. 1-enamel is ectodermal in origins2-it is derived from inner enamel epithelium of enamel organ.3-mature enamel is completelynon cellularAmeloblasts are derived from outer enamel epithelium)Mature enamel is completely acellular (True or false )
  • 3. Physical characters 1-Thickness 2-Color 3- Hardness 4- Tensile strength 5-Permeability 6-Solubility
  • 4. thickness It is thick at the incisal edge and cusp tip of molars and premolars (2-2.5 mm) and ends cervically as knife edgeThe thickest part of the enamel is present in---------, and………….
  • 5. colorThick enamel---------------------- bluish white Decrease in thickness-----------------------yellow due to the underlying dentinHealthy thick enamel is -------- in color, while thin enamel is …………in color
  • 6. hardnessEnamel is the hardest calcified tissue in the bodyBecause of its high content of minerals.Enamel can withstand load of mastication andresist wear process.------- is the hardest calcified tissue in the body.Enamel is the hardest calcified tissue in the body (give a reason)
  • 7. Tensile strengthAlthough it is hard , enamel is extremelybrittle and depends on the strength ofthe underlying dentin.Tensile strength of enamel is greater than that of dentin ( true or false)
  • 8. permeabilityEnamel is selectively permeable,permitting partial or complete passageof ions due to the presence ofmicroscopic pores. Enamel is completely impermeable to ions (False or true)
  • 9. solubilityEnamel dissolves in acid media. Itssurface is less soluble than deepenamel.
  • 10. Chemical compositionMature enamel consists of: Mainly(96%) inorganic substance Small (3%) amount of organic substance & 1%) water
  • 11. Inorganic component Mainly calcium phosphate crystals (hydroxyapatite crystals)
  • 12. organic componentMainly non collagenous proteins: A- amelogenins B- non-amelogenins
  • 13. Microscopic structure1-Rods (prism).2- Rod sheath.3-Inter rodal cement substance
  • 14. Ground section Decalcified section the organic the inorganicsubstance is burnt substance is dissolvedand the inorganic and the organicsubstance remain substance remain
  • 15. Enamel rods1- Course.2- Number.3- Transverse striation.4- Direction.5- Gnarled enamel.
  • 16. Course: the enamel rod starts straightat dentino-enamel junction (D.E.J.)for about 30 µ then has a wavycourse till near the outer surface ofenamel where it become straightonce more.
  • 17. The number of the enamel rods varies from 5 millions in lower lateral incisor to 12 millions in the upper first perm.The number of the rods equals the number of the ameloblasts. anent molar. At the tooth surface there are about 20000- 30000 enamel rods in 1 mm2 The density of the rods is at the DEJ about 10% higher than at the enamel surface.The total number of enamel rods varies from------- to ---------
  • 18. transmission electron microscope
  • 19. Scanning electron microscope
  • 20. Transverse striation of rods
  • 21. Direction of rodspermanent tooth Deciduous tooth
  • 22. Gnarled enamel Twisted Gnarled course of enamel enamel rods DGnarled enamel is twisted and intertwined rodestructure associated with increase strength of theenamel ,Present mainly in the incisal edges and tipof the cusps. (enamel rods develop in planes oftension).Give short account on gnarled enamel
  • 23. Gnarled enamel
  • 24. Rod sheathL.M. distinct thin layer peripheral to the rods Different refractive index, darker and more acid resistant, and less calcified and more organic.E.M. not distinct layer, but organically rich inter- rod space devoid of crystals.
  • 25. Inter rod substanceL.M. distinct cement substance with higher refractive index.E.M.tail of the adjacent rod with different direction of the crystals
  • 26. INCREMENTAL LINES OF RETZIUS
  • 27. NEONATAL LINE Prenatal enamel Neonatal line Postnatal enamel
  • 28. PERIKYMATAThe external manifestation of theincremental lines of Retzius representedas transverse wave like grooves on thesurface of the enamel are known asperikymata.
  • 29. HUNTER SCHREGER BANDSThe dark bands (Diazones) absorb the •light where the light bands (Parazones)reflect the light.
  • 30. ENAMEL TUFTANDENAMEL LAMELLAE
  • 31. ENAMEL SPINDLEIt makes the area hypersensitive to painEnamel spindles are :A- odontoblastic processes cross the dentinoenamel junction.B- remnants of ameloblasts.C- enamel rods develop in planes of tension.
  • 32. Surface structureIt is relatively structure-less layer covers the cervical region of the teeth. 30um in thickness in 70% ofPeople, and it is hyper-mineralized.
  • 33. ENAMEL CUTICLEPrimary cuticle secondary cuticleIt is delicate membrane covers It is non cellular keratinized layer the crown of the newly formed by reduced enamelErupted tooth. It has epithelium after tooth eruption,the same Structure as After removal of the primary one basement membrane by wear and brushing
  • 34. ENAMEL pellicleIt is a glycoprotein of saliva that covers the tooth immediately after eruption. It reforms within hours after removal. ENAMEL plaqueWithin a day or two after the pellicle has formed itcolonized With microorganisms to form bacterialPlaque.

×