Enamel and Amelogenesis Flashcards
What is enamel made up of? What is special about it?
96% Hydroxyapatite. 4% Organics and water. Hardes substance in the body.
What are enamel rods?
Tightly packed hydroxyapatite crystals that are perpendicular to the DEJ.
What are the crystal orientations in the Enamel Rod head and tail?
Rod head=Oriented with long axis
Rod tail=Cross axis
What are lines of Retzius?
Enamel striae that grow pointed incisally from the DEJ.
What is Perikymata?
Grooves on surface of the tooth where Lines of Retzius terminate.
What are Hunter-Shreger bands?
Bands in enamel from the different orientations of the rods.
What are enamel tufts?
Groups of hypomineralized enamel rods.
WHat are enamel Lamellae?
Hypocalcified enamel cracks.
What is aprismatic enamel?
Enamel crystals on outermost tooth. Lack rods.
What is Gnarled Enamel?
Enamel rods over cusps that are twisted and intertwined.
Where do ameloblast first lay down enamel?
Starts at crown down to the CEJ.
What differentiate to become Ameloblasts?
Inner enamel epithelium.
Describe the stages of Ameloblast life cycle?
- Morphogenic: IEE to ameloblast
- Histodifferentiation: Organelles form and increase
- Pre-Secretory: Organelles make vesicle matrix
- Secretory: Secretes the vesicles with crystals.
- Maturative phase: Ruffle and Smooth, Death
- Protective: Secretes final primary cuticle
What are Tomes’ Fiber? Tomes’ Process?
Fiber: Odontoblast Process
Process: Process on Ameloblast.
The distal and proximal Tomes process make what?
Distal=Rod enamel
Proximal=Interrod enamel.
What is the role of the stratum intermedium?
Nourish ameloblasts.
What do ruffle-ended and smooth-ended ameloblasts do?
Ruffle:Things transported out to up mineral content
Smooth: Things transported in (like water) to up mineral content.
What are Amelogenin, Enamelin, and Ameloglastin? What do they do?
Enamel Proteins
- Amelogenin: 90%, helps form enamel
- Enamelin: Helps crystal formation
- Ameloblastin: Helps ameloblast to adhere to enamel.
What occurs during the Protective or end phase of ameloblasts?
Secrete the primary cuticle and attach by hemidesmosomes.
What forms the papillary layer of enamel?
Stratum Intermedium, Stellate reticulum, outer enamel epithelium.
What forms the Reduces enamel epithelium? Where is it?
Papillary layer and Ameloblasts. Layer over tooth as it erupts.
