Flashcards in Enamel Tissue Deck (52)
T/F - Enamel is the hardest of the 4 mineralized tissues of the body
T/F - All 4 mineralized tissues of the body are connective tissue
False - Enamel is NOT a connective tissue
T/F - All mineralized tissues have a partially mineralized (immature) stage, and a fully mineralized (mature) stage
False - Enamel is the only mineralized tissue that goes through an immature stage....the other 3 go from unmineralized to mineralized (never partially mineralized)
T/F - Enamel formation is finite
True - Ameloblasts complete its enamel formative cycle once the thickness of enamel is reached at a site
What is the first appearing mineralized tissue in a developing tooth? What is second?
Dentin is first
Enamel is second
What is lacking in enamel?
Enclosed cells (acellular)
Blood vessels (avascular)
Lymph vessels (alymphatic)
What tissue in a tooth contains enclosed cells, nerves, blood vessels, and lymph vessels?
A composite biological mineral with apatite crystals oriented in a complex, three-dimensional pattern
Hardness of enamel
5 on Moh's scale - comparable to mild steel
Can withstand both shearing and impact forces well
Brittle without dentin support
Hue depends on location, surface condition of enamel, attraction to stain substances, and age changes
What is required for enamel to maintain its integrity?
A wet environement
Normal, slow wearing of tooth substances under the stress of mastication
Abnormal wearing of tooth substance from extraoral substances (toothpick)
Abnormal wearing of tooth substances from acid
Microporosity of enamel
The pathway for diffusion of small molecules such as water
Electrochemical effects on pore walls lead to carious lesions
Remineralization of enamel
Mineral is returned to the molecular structure of enamel by the way of saliva
When demineralization exceeds remineralization, cavitation occurs
Inorganic substances of enamel
96% of enamel by weight
Hydroxyapatite crystals - principle component is calcium hydroxyapatite
How do enamel crystals compare to other mineralized tissues?
Enamel crystals are larger and consist of more impurities (fluoride, carbide)
Organic substances of enamel
1% by weight
What are the types of proteins unique to enamel?
Amelogenin and non-amelogenin
What are some non-amelogenin proteins
What is the most prominent organic substance of enamel?
Amelogenin - a seed protein for normal mineralization
Enamel protein arrangement
Arranged in a lace-like patern throughout the volume of enamel and clsoesly associated with the surface of the crystals
Enamel is the only mineralized tissue that does not contain what?
Water in enamel
3% of weight
Distributed throughout the volume of enamel by the way of micropores between crystals and proteins
Most of the water forms a hydration shell around the crystals
What is the clinical importance of water to the enamel?
-Provides a route for fluoride ions, calcum, and phosphorous ions for remineralization
-Provides distribution for whitening substances, artificial, and natural substances
-Provides distribution for acidophilic microorganisms, age changes, etc
Age changes to enamel
Enamel wears slowly (attrition)
Composition of surface changes
Fluoride increases at the surface
Porosity is reduced
Less susceptible to caries
Subject to changes due to systemic age changes
What are the different CEJ relationships?
Cementum overlaps enamel (most common)
Cementum meets enamel
Cementum does not meet enamel (least common)
What is the clinical significance of CEJ relationship?
The CEJ relationships vary around the tooth and form tooth to tooth