1. Mineral Content (Hydroxyapatite) - 96% 2. Enamel Matrix 1% 3. Water 3%
1. Prisms (Rods) 2. Sheath
Enamel Prisms (Rods)
Mineralized crystalline structure of enamel. Extends width of enamel from DEJ to outer surface. Perpendicular to DEJ. "Keyhole shape", largest mass
Water and Matrix present. Formed by ameloblasts. Interprismatic or Interrod region covers rod/prism.
How many ameloblasts does it take to make a complete rod and sheath?
It takes 4 ameloblasts
How many cells does it take to make the head?
How many cells does it take to make the tail?
Ameloblasts must have
Tome's process present to lay down enamel and form prism
Proteins found in developing enamel. Form bulk of matrix
Proteins found in mature enamel
Enamel development stages
1. Formative 2. Calcification 2. Maturation
There are two groups of matrix proteins (Amelogenins and Enamelins). Ameloblasts lay matrix but then break it down to allow room for hydroxyapatite
Crystals are deposited
Crystals enlarge (more amelogenins are removed to allow for growth of crystals)
Enamel Protective Stage
Enamel complete so enamel organ is now reduced enamel epithelium. Reduced enamel epithelium covers and protects new enamel prior to eruption. Ameloblasts secrete basal lamina to cover enamel (important in establishment of DGJ).
Newest enamel is located
Close to CEJ
Junctional epithelium is located
Directly above Connective Tissue
Sealants are placed on
Permanent teeth that have been in the oral cavity for about 1 year
Taking enamel and cutting it cross-sectional and longitudinal and laying those 2 cuts next to each other. Band appearance
Enamel prisms that are twisted around each other at cusps or incisal edges.
Runs from DEJ to very outside. Fracture line. Only seen microscopically. Sensitivity because tubules are open to outer environment.
How many different ways may Lamellae form?
3 different ways
Found from DEJ to inner 1/3 of enamel. May be calcified or not. Resembles bundles of grass. Bigger than spindles.
Develop when odontoblastic processes are not withdrawn quickly. Tiny. Non-calcified enamel. Located next to DEJ.
Length of rods and tubules are irregular. Scalloped ridge increases adherence and strength. Prismless area.
Outer surface of enamel
Is prismless on a newly erupted tooth
Fluoride uptake requires
Enamel mineral content
Dentin mineral content
Bone and Cementum mineral content
40 - 45%
Which is a larger crystal, fluorapatite or hydroxyapatite?
Pre-Eruptive Calcification Stage
Fluoride is deposited during formation of Enamel crystals and incorporated as fluorapatite. Benefit from systemic fluoride.
Pre-Eruptive Maturation Stage
Fluoride Deposition continues after calcification. Benefit from systemic fluoride.
After eruption and throughout life of teeth. Topical uptake and rapid uptake during 1st years after eruption.