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32 Cards in this Set
- Front
- Back
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Describe enamel |
Hard tissue covering of the tooth crown and hardest of all the biological tissues |
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Enamel is derived from ________? |
Ectoderm |
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Enamel is made up of? |
Enamel is highly mineralised (inorganic) content - made up of hydroxyapatite (calcium + phosphate) crystal units (prisms and rods) |
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What is the specialised enamel-making cells? |
Ameoloblasts |
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What is calcium hydroxyapatite and what is its unit cell formula? |
It is a carbonated biological apatite (impure) Unit cell formula: Ca10 (PO4)6 (OH)2 |
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Ground section of enamel and dentine |
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What is the origin of the enamel protein? |
Ectodermal |
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What is amelogenin and what does it do? |
Major protein constituent of the developing enamel matrix. Needed for rods. |
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What is ameloblastin and what does it do? |
A minor protein of the enamel matrix. It is for attachment to dentine. |
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What are enamelins and their function? |
It is a enamel-specific proteins, which have high affinity for binding hydroxyapatite crystals. |
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Enamel matrix is formed from___? Dentine originates from the ________ ________? |
Enamel matrix = enamel organ Dentine = dental papilla |
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What develops from dental follicle? |
Cementum and periodontal ligament |
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Identify what stage |
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Identify what stage |
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Identify the different types of cells develop in enamel organ |
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What are the four components of enamel organ? |
1. Outer enamel epithelium (OEE) 2. Stellate reticulum (SR) 3. Inner enamel epithelium (IEE) 4. Stratum Intermedium (SI) |
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Describe stellate reticulum |
Centre of the enamel organ - rich in glycosaminoglycans (hydrophilic) |
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Describe OEE |
cuboidal cells on the periphery of the enamel organ |
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Describe IEE |
short columnar cells that will eventually become ameloblasts |
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Describe Stratum Intermedium |
derived from SR and IEE - rich in the enzyme alkaline phosphate |
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Identify what stage |
Bell stage |
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Enumerate the enamel production |
1. Morphogenic ("preparatory") 2. Histodifferentiation 3. Initial secretory (no Tomes) 4. Secretory (+ Tomes) 5. Ruffled-ended ameloblast 6. Smooth-ended ameloblast 7. Protective stage ("end of life") |
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Types of enamel forms: |
First-formed enamel - prismless Bulk of tissue with prisms Last-formed enamel - prismless |
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What are the enzymes involve in extracellular processing and degradation of enamel proteins? |
Enamelysin Kallikrein4 (KLK4) |
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What are the enzymes involve in bone resorption (bone remodeling)? |
MMP-9 and cyteine proteases |
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What are the enamel-related disorders? |
1. Amelogenesis imperfecta - cause: malfunctioning enamel matrix proteins 2. Fluorosis 3. Molar incisor hypomineralisation (MIH) - cause: trauma? |
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What is the composition of mature human enamel? |
Inorganic (mineral) - weight: 95%, volume: 86% Organic (protein) - weight: 1%, volume: 2% Water - weight: 4%, volume: 12% |
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What is the shape of calcium hydroxyapatite in enamel? |
Hexagonal crystals |
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What are rods? |
Millions of carbonated hydroxyapatite are arranged in long, thin structures called rods. |
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What are inter rod? |
Area between the rods. PS: same crystal composition, different crystal orientation |
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Describe appositional stage for enamel |
1. Fomration of dental hard tissues 2. Transition from the synthesis of soft tissue to hard tissue formation (enamel matrix formed form the enamel organ [IEE + SI + SR + OEE]) (dentine originates from dental papilla) |
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Name 6 other structures that can be found in the enamel.
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Striae of Retzius - enamel “growth rings” Cross striations – cross-bands every 4 mm - circadian pattern of rod formation Hunter-Schreger bands – optical phenomena Enamel tufts – directional changes in rod groups Enamel lamella – cracks in the enamel Enamel spindles – “invasion” by odontoblasts |
