Dentinogenesis/Amelogenesis (Gonzales 1) Flashcards
Origin of dentin
Dental papilla
Origin of enamel
The enamel organ
What happens to the outer enamel epithelium?
Degenerates
What happens to the inner enamel epithelium?
Forms enamel
What happens to the stellate reticulum?
Allows room for growth
What happens to the stratum intermedium?
Nutrition of the inner enamel epithelium
Formation of the DEJ occurs during the _____ stage.
Bell
Formation of the DEJ forms by reciprocal interaction (induction between the _____ and _____).
- Epithelium
- Ectomesenchyme
Steps of DEJ formation:
- Formation of the _________.
- Differentiation of cells in the dental papilla into _______.
- Secretion of ______ by the odontoblasts.
- Differentiation of the inner enamel epithelium into ________.
- Secretion of the initial layer of enamel by ________.
- Inner enamel epithelium
- Odontoblasts
- Mantle dentin
- Ameloblasts
- Ameloblasts
Odontoblast differentiation: ______ derived from ectomesenchyme of neural crest origin lie next to the basement membrane of inner enamel epithelium.
Squamous cells
Odontoblast differentiation: Squamous cells become _____ and develop ______ which extend toward the future DEJ. Contact with ________ initiates molecular signals that cause the cell to differentiate.
- Columnar
- Cell processes
- Basement membrane
Odontoblast differentiation: the ________ represents the location of the future dentino-enamel junction.
Basement membrane
Odontoblast differentiation: During polarization, the nucleus _____ away from the cell process (and basement membrane) and takes on _______ of a protein secreting cell with well developed RER and golgi apparatus.
- Migrates
- Organization
Mantel dentin is a narrow band of dentin that is formed under the __________ of the inner enamel epithelium.
Basement membrane
Formation of Mantle Dentin: thickness ranges between ______ and is a ______ step process.
- 10 to 50 micrometers
- Two
Formation of Mantle Dentin: Secretion of the unmineralized organic matrix (pre-dentin) contains _______ and _______ then mineralization (inorganic matrix).
- Glycosaminoglycans
- Dentin specific proteins
Differentiating odontoblasts secrete _________ between developing cell processes.
Organic matrix (pre-dentin)
Predentin is composed of _______, many of which are involved in the formation of hydroxyapatite crystals and _______, thick bundles of collagen fibers oriented perpendicular to the future DEJ. This induces formation of ________.
- Numerous proteins
- Korff fibers (alpha fibers)
- Ameloblasts
______ bud off cell processes of odontoblasts. These contain ________ needed for calcification of extracellular matrix.
- Matrix vesicles
- Alkaline phosphatase and other enzymes
Hydroxyapatite crystals outgrow from the ________.
Matrix vesicles
Hydroxyapatite forms spheres, called _______, on the collagen fibers, which fuse to form ________.
- Calcospherites
- Mineralized dentin
Dentinal tubules are potential spaces in the dentinal matrix that contain _______, ________, and _______.
- Odontoblastic cell process
- Nerve endings
- Extracellular fluid
_______ represents all dentin formed after the initial formation of mantle dentin.
Circumpulpal dentin
Formation of Circumpulpal Dentin: Retreating odontoblasts secrete small caliber collagen fibers called ________.
Beta fibers
Formation of Circumpulpal Dentin: Mineralization occurs directly on the _______ in a linear fashion, called the __________.
- Collagen fibers
- Mineralization front
Formation of Circumpulpal Dentin: There is always a layer of _______ separating the odontoblast cell bodies from the mineralized dentin.
Pre-dentin
Mantle Dentin:
- ______ micrometers next to DEJ
- Contain ______ fibers
- Mineralization by ______
- Induces formation of ________
- 10 to 50
- Alpha or Korff’s (thick)
- Matrix vesicle
- Ameloblasts
Circumpulpal Dentin:
- _____ of the dentin surrounding the pulp
- Contains _______ fibers
- Mineralization occurs on ________ and is mediated by _________.
- Most
- Beta or thin collagen
- Collagen fibers
- Dentinal proteins
Enamel rods (prisms) made of ________, which are the area between ______ (horizontal striations).
- Rod segments
- Daily growth lines
The rod is separated by ______ that holds rods together. We now know that this is _______.
- Interrod (interprismic) substance
- Interprismic enamel aka interrod enamel
The enamel rod or prism is:
- The structural unit of _______.
- Composed of numerous _______.
- Runs from the ______ to the ______.
- Shaped like _______.
- Enamel
- Rod segments
- DEJ to the tooth surface
- Keyhole
Life Cycle of Ameloblast:
- Morphogenic Stage: _____ of tooth
- Organizing Stage: _______ of cells
- Secretory Stage: Secretion of _______
- Maturation Stage: _______ and _______ of enamel proteins
- ______ and ______ Stage
- Shape
- Polarization
- Enamel proteins
- Mineralization and resorption
- Protective and Desmolytic
Regulation of Enamel Structure:
- Secretory Stage: build up of _______
- Maturation Stage: removal of _______
- Enamel layer
- Peptides
In the morphogenic stage, the interaction between _____ and _____ determines the shape of the tooth in the ___ stage.
- Ectomesenchyme and inner enamel epithelium
- Bell
In the organizing stage, ______ of the organelles away from the ________ to secrete proteins toward the future _____.
- Polarization
- Basement membrane
- DEJ
The formation of Tomes’ process occurs during the _______ Stage.
Secretory
Formation of Tomes’ Process:
1. A layer of ______, which will become the future _____, is laid next to the basement membrane.
- Aprismic enamel
- DEJ
Formation of Tomes’ Process:
2. Enamel protein is secreted in the intercellular spaces between cells forming the _________.
Interrod or interprismic enamel
Formation of Tomes’ Process:
3. Portion of the cell surrounded by _______ becomes the Tomes’ Process
Enamel
Formation of the Rod Space occurs during the ______ Stage.
Secretory
Formation of the Rod Space:
1. Cells retreat from DEJ while secreting additional _______ in the intercellular space contributing to the linear growth of the _______.
- Enamel proteins
- Interprismic enamel
Formation of the Rod Space:
2. A potential space (Rod Space) containing the Tomes’ process is located between the _______ of adjacent cells
Interprismic enamel
Formation of the Rod Segment occurs during the _______ Stage.
Secretory
Formation of the Rod Segment:
- Space becomes filled with _____.
- Results in ______ micrometer segment of enamel.
- Multiple layers of rod segments form the ______.
- Takes _____ to form a rod segment.
- Enamel
- 2 x 2
- Enamel rods
- 24 hours
______ are dark horizontal striations on the enamel rod that represent daily growth of rod segments.
Striations
Four ameloblasts make one enamel rod with keyhole shape due to ________.
Hexagonal shape of Tomes’ process
Formation of Dentino-Enamel Junction: The surface of the mantle dentin is ______.
Not smooth
Formation of Dentino-Enamel Junction: Odontoblast cell processes extend beyond the dentin’s surface, called _______.
Enamel spindles
Formation of Dentino-Enamel Junction: The _______ of inner enamel epithelium breaks down.
Basement membrane
Formation of Dentino-Enamel Junction: ________ secrete a layer of aprismic enamel.
Pre-ameloblasts
Formation of Dentino-Enamel Junction: Apical ends of odontoblast cells processes that become surrounded by enamel are called ______.
Enamel spindles
In the maturation stage of the life cycle of the ameloblast, _______ with hydroxyapatite occurs as well as resorption of _________ (alternating ruffled and smooth borders allow this).
- Mineralization
- Enamel proteins
Amelogenesis Imperfecta: List the three steps in the formation of enamel formation in which anomalies can occur
- Secretion
- Calcification
- Maturation
Amelogenesis Imperfecta: Secretion
Not enough enamel matrix is secreted
Amelogenesis Imperfecta: Calcification
Hypocalcification
Amelogenesis Imperfecta: Maturation
Crystal growth is limited
Hypoplastic Amelogenesis Imperfecta is a defect in ________, which is very thin and cannot be detected on radiograph. It results in a rough pitted surface, although enamel is hard and (+) calcification.
Amount of enamel secreted
Hypocalcified Amelogenesis Imperfecta is when ______ occurs. The matrix formation is of normal thickness, but enamel is soft (“swiss cheese”) and teeth are usually brown due to extrinsic stains.
No calcification
Hypomaturation Amelogenesis Imperfecta is a defect in _______ in which enamel is softer than unaffected enamel but stronger that hypocalcified AI. Results in mottled enamel with brown pigment and snow capped incisal/occlusal surface.
Mineralization
In the protective stage of the life cycle of the ameloblast, the _______ is formed, which consists of _______ and ________.
- Reduced enamel epithelium
- Post-ameloblasts and stratum intermedium
______, which can be associated with unerupted or partially erupted tooth, are lined with epithelial cells derived from the reduced enamel epithelium.
Dentigerous cysts
In the desmolytic stage of the life cycle of the ameloblast, release of _______ during eruption to ________ occurs.
- Hydrolytic enzymes
- Break down connective tissue
