Tooth Microstructure and Dental Pulp Morphology Part I Flashcards
- Enamel - the highly mineralized tissue covering the anatomical crown of a tooth. It is the ____ tissue in the body.
- Inorganic salts ___%
- Organic matter _%
- Water ___%
- Enamel - the highly mineralized tissue covering the anatomical crown of a tooth. It is the hardest tissue in the body.
- Inorganic salts 95-97%
- Organic matter 1%
- Water 2-4%
Enamel – Chemistry
•Inorganic matrix is composed of ;
–___
___
–__ ___
–___ ___
–___ ___
The calcium and phosphate join to form ___ ____ which makes up the majority of the matrix. Note: this means that calcium and phosphate make up the greatest percentage of the inorganic matrix.
•Inorganic matrix is composed of ;
–Calcium
–Phosphate
–Calcium Carbonate
–Magnesium Phosphate
–Calcium Fluoride
The calcium and phosphate join to form Calcium Hydroxyapatite which makes up the majority of the matrix. Note: this means that calcium and phosphate make up the greatest percentage of the inorganic matrix.
Enamel – Formation
- Formation begins with the ____ secreting the ____ proteins in the embryonic tooth buds.
- Amelogenins form ____
–These 18-20 nanometer structures regulate the formation and organization of tooth enamel by controlling the crystalline growth
–Amelogenins also ___ ___ to form the ___ __ ____ within which the crystals of mineralization start to form
- Formation begins with the ameloblasts secreting the amelogenin proteins in the embryonic tooth buds.
- Amelogenins form Nanospheres
–These 18-20 nanometer structures regulate the formation and organization of tooth enamel by controlling the crystalline growth
–Amelogenins also self assemble to form the extra-cellular matrix within which the crystals of mineralization start to form
Enamel – Formation
–The crystals are __ ____arranged at ___ angles to the ____ of the tooth
–The crystals are hexagonal prisms arranged at right angles to the surface of the tooth
Enamel
- The hardness of enamel has been compared to that of a good ___ __ ___
- The hardness of enamel helps the tooth ___ ____
- Enamel’s hardness also makes it ____ resistant to decay than dentin or cementum.
- Compared to ___ and ___ ___ enamel ranks ___ on the hardness scale. When soft, one knows that enamel (or dentin) is ___
- The hardness of enamel has been compared to that of a good stainless steel alloy.
- The hardness of enamel helps the tooth resist wear.
- Enamel’s hardness also makes it more resistant to decay than dentin or cementum.
- Compared to diamond and tungsten carbide, enamel ranks eighth on the hardness scale. When soft, one knows that enamel (or dentin) is diseased.
Enamel - Solubility
- The presence of ___ and___ are known to affect the solubility.
- ___, ___, and ____ decrease solubility.
- ____, such as lemon juice and vinegar, ___ the solubility. Note - many soft drinks are acidic. Years ago, auto mechanics used Coca Cola to clean deposits off the car battery posts and clamps.
- Nature tries to saturate the saliva with ___, ___ and ___e ions to help protect the teeth.
- The presence of alkalis and acids are known to affect the solubility.
- Sodium, calcium, and phosphates decrease solubility.
- Acids, such as lemon juice and vinegar, increase the solubility. Note - many soft drinks are acidic. Years ago, auto mechanics used Coca Cola to clean deposits off the car battery posts and clamps.
- Nature tries to saturate the saliva with sodium, calcium, and phosphate ions to help protect the teeth.
Enamel
- As a general rule, enamel___ ___ repair itself.
- However, incipient caries of enamel can______ if the surface is not cavitated.
- The use of _____ varnishes, rinses, toothpastes and gels can be helpful if the patient has areas of enamel that are partially de-mineralized.
- Flouride ions enhance the precipitation o___ and ___e ions from the___ and make the re-mineralized enamel___ resistant to decay, i.e. ____ e as opposed to hydroxyapatite
- As a general rule, enamel does not repair itself.
- However, incipient caries of enamel can re-mineralize if the surface is not cavitated.
- The use of fluoride varnishes, rinses, toothpastes and gels can be helpful if the patient has areas of enamel that are partially de-mineralized.
- Flouride ions enhance the precipitation of calcium and phosphate ions from the saliva and make the re-mineralized enamel more resistant to decay, i.e. fluorapatite as opposed to hydroxyapatite
Enamel - Arrested Lesions
- Arrested lesions can be observed clinically as ___t, but ____ spots.
- These spots are usually___ or ____. The change in color is believed due to trapped, ____ debris and/or ___ ions within the enamel.
- These arrested lesions are _____d and are ____ to subsequent caries.
- Arrested lesions occur mainly in ___ and ____. They may be restored for esthetic reasons.
Enamel
- Tensile strength - causes enamel to be___ and require ____ support.
- Restorative preparations must be extended to areas of dentinal support. This means leaving little____ ____ .
- Reduced salivary flow may lead to tooth____ problems due to lack of natural cleansing and lack of available calcium and phosphate ions for ____
- Tensile strength - causes enamel to be brittle and require dentinal support.
- Restorative preparations must be extended to areas of dentinal support. This means leaving little unsupported enamel.
- Reduced salivary flow may lead to tooth decay problems due to lack of natural cleansing and lack of available calcium and phosphate ions for re-mineralization.
Enamel
- Enamel is generally a ___ ___e, but at times appears yellowish due to the reflection of the color of the underlying ____
- The smooth enamel surface is very helpful in the ___ of ___. This smoothness makes enamel somewhat ___ ___ and helps prevent food from ___ to its surface.
- Enamel is generally a translucent white, but at times appears yellowish due to the reflection of the color of the underlying dentin.
- The smooth enamel surface is very helpful in the flow of food. This smoothness makes enamel somewhat self-cleansing and helps prevent food from sticking to its surface.
Enamel -Translucency
- Translucency - the ability of ___ to)___ ____ an object.
- The reproduction of the “enamel” can be very important when making esthetic restorations.
- Dentists sometimes wait to take the__ ___ for a crown until___ the preparation is finished.
- Translucency - the ability of light to pass through an object.
- The reproduction of the “enamel” can be very important when making esthetic restorations.
- Dentists sometimes wait to take the dentin shade for a crown until after the preparation is finished.
Enamel
•The enamel is thickest on the___ and ___ surfaces of the permanent teeth.
•The enamel is thickest on the incisal and occlusal surfaces of the permanent teeth.
Dentin - Physical Properties
•Dentin is significantly ___ than enamel, but it is harder than ___ or ___.
Dentin becomes ___ with increasing age.
- The hardness of dentin averages about __ ___that of enamel.
- Inorganic salts ___%
- Organic matter ___%
- Water __%
- Dentin is significantly softer than enamel, but it is harder than cementum or bone. Dentin becomes harder with increasing age.
- The hardness of dentin averages about one fifth that of enamel.
- Inorganic salts 65-75%
- Organic matter 20-30%
- Water 5%
Dentin
- Dentin - the hard tissue which forms the ___ __ of the tooth. It surrounds the ___ ___.
- It is covered by the enamel in the ___ crown and by cementum in th -___ root.
- Dentin ___ repair itself.
- Dentin - the hard tissue which forms the main body of the tooth. It surrounds the pulp cavity.
- It is covered by the enamel in the anatomical crown and by cementum in the anatomical root.
- Dentin may repair itself.
Functions of Dentin
- Supports the ____ - loss of underlying dentin requires special consideration in preparation design.
- Poor t___ ____y - reduces trauma from normal thermal stimuli. Dentin provides a fairly thick wall of____n around the pulp.
- Note - excessive heat from dental procedures has killed many teeth.
- Transmits -__ ____ n - the fibers within the__ ___s are responsible for the conduction of stimuli.
- Supports the enamel - loss of underlying dentin requires special consideration in preparation design.
- Poor thermal conductivity - reduces trauma from normal thermal stimuli. Dentin provides a fairly thick wall of insulation around the pulp.
- Note - excessive heat from dental procedures has killed many teeth.
- Transmits sensory information - the fibers within the dentinal tubules are responsible for the conduction of stimuli.