• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/61

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

61 Cards in this Set

  • Front
  • Back
When does odontogenesis begin?
Between the 5th and 6th week of in utero development.
What are the two major events involved in this process?
Morphodifferentiation (determines the shape of the crown of the tooth) and cytodifferentiation that differentiates the special groups of cells required for the formation of dental tissues.
Name the phases of morphogenesis.
Bud, cap and bell stages.
What two specific cell populations are involved in morphogenesis?
Oral epithelial cells (that give rise to the enamel organ) and neural crest mesodermal cells that I nduce the oral cells to proliferate as well as form the dental papilla.
What cells would have to be absent for odontogenesis not to occur?
Neural crest mesoderm cells.
What are the 2 laminae formed by proliferation of the oral ectoderm cells?
The vestibular and dental laminae.
What does the vestibular lamina form?
The vestibule (the space between the lip and gingiva).
What two layers are exhibited in the cap stage?
Outer and inner dental epithelium.
Further differentiation of the cap results in the formation of what structure?
The enamel knot
From which structure does the bud of the permanent tooth arise?
The dental lamina of the primary tooth.
are the two components of the bell stage of tooth development?
The epithelial component and the mesenchymal component.
Name the four distinct layers of the epithelial component as well as the organ they form.
1. inner dental epithelium (forms the enamel); 2. stratum intermedium (controls passage of materials into and out of the future ameloblasts); 3. stellate reticulum (forms a fluid-filled space into which the enamel layer can grow); 4. outer dental epithelium (fuses and is eventually shed).
What are the two components of the mesenchymal aspect?
The dental papilla and the dental sac (follicle).
In what stage does the cervical loop become prominent?
The bell stage.
What is the cervical loop?
The downward growing edge of the cap from which new inner and outer dental epithelial cells form.
What continued downgrowth of the cervical loop form?
The anatomical crown of the tooth.
What is the function of the stratum intermedium?
This layer of cells is found behind the ameloblast layer and controls what passes between these cells and the capillaries that indent the ODE.
What is the function of the stratum intermedium?
It provides a fluid-filled space into which the enamel layer can grow to give the tooth its anatomical shape for the crown.
What do the cells of the IDE eventually become?
Ameloblasts (enamel forming cells).
What eventually happens to the cells of the ODE?
They fuse with the ameloblasts and stratum intermedium to become the reduced enamel epitheloium that is shed either during eruption or functional occlusion.
What are epithelial (Serre’s) pearls?
The remnants of the epithelial cells that formed the dental lamina as it begins to break down.
Why are epithelial pearls clinically important?
Persistent islands of epithelium can become focal points for the formation for certain oral pathologies.
What are the 3 regions (features) of the tooth germ?
The dental organ, dental papilla and dental sac (follicle).
What does each region of the tooth germ give rise to in the adult tooth?
The dental organ = enamel; dental papilla = dental pulp and dentin layers; dental sac = cementum, PDL and alveolar bone socket.
do the first series of cellular interactions in odontogenesis result in?
Morphodifferentiation (interaction between the oral ectoderm epithelial cells and the neural crest mesenchymal cells).
What do the second series of cellular interactions in odontogenesis result in?
The initiation of cytodifferentiation (differentiation of the cell types responsible for the formation of dentin and enamel).
What causes the cells of the peripheral region of the dental papilla to differentiate into odontoblasts?
The development of the cells of the IDE into preameloblasts which secrete compounds into the underlying basal lamina that causes the peripheral pulp cells to become odontoblasts.
What causes the preameloblasts of the IDE layer to begin secreting enamel (amelogenin)?
Temporary contact odontoblast cell processes plus the initiation of dentin secretion.
What is the membrana perforata?
The old basal lamina under the IDE layer that breaks done to allow the odontoblast processes to contact the overlying preameloblasts.
In what region of the tooth does cytodifferentiation first occur?
The incisal aspect of the cusp.
To which region does it sequentially extend?
It extends down to the cervix (future enamel-cementum jucntion).
What are the 5 functional stages in cytodifferentiation and what occurs in each?
1. Morphogenic (initiation) stage: dental pulp cells proliferate and IDE cells ready for transformation into preameloblasts. 2. Organizing stage: dental pulp cells round up into odontoblasts and the IDE cells organize their cytoplasmic components for the transformation into prealmeloblasts. 3. Formative (secretory) stage: odontoblasts begin dentin secretion (odontogeneisis) and the overlying pre-ameloblasts become secretory ameloblasts and begin secreting amelogen. 4. Maturation stage: transformation of immature enamel into mature enamel. Ameloblasts stop secreting enamel (loose their Tome’s process) and exhibit a ruffled border. Prismless enamel is formed at the end of this phase., 5. Protective stage: The ruffled border secretes a cuticle for the maturative ameloblasts to anchor to. These cells plus the overlying stratum intermedium and ODE cells all form the reduced enamel epithelium.
What is a maturative ameloblast?
One whose Tome’s process has resorbed and exhibits a ruffled border . This cell membrane will then become the basal aspect again and anchor via hemidesmosomes to the newly secreted cuticle.
How does it differ from a secretory ameloblast?
It lacks an active enamel-secreting face or Tome’s process.
What is a Tome’s process?
A shovel-shaped slanted apical cell membrane that secretes amelogens into the surrounding environment that will mature into enamel.
What is a ruffled border?
A resorbed Tome’s process that secretes prismless enamel to “smooth off” the secretory surface.
What is involved in enamel maturation?
The water and organic component of the newly secreted amelogens (enamelins) are replaced with calcium and phosphate ions.
List the similarities between dentin and enamel formation?
Similarities: secretory ends of odontoblasts and ameloblasts face the shared basal lamina; they both move away from the basal lamina as secretion begins; both layers communicate between cells via gap junctions.
What are the major differences between them?
Differences: odontoblasts produce CT-like material, ameloblasts produce no collagen; odontoblasts leave a long process in their matrix, ameloblasts do not; dentin initially (as in predentin) contains no HA salts, enamel matrix contains some as soon as it is deposited.
Where does root formation start?
After crown formation is complete and eruption begins.
what is the epithelial diaphragm?
The continuation of the cervical loop down into the root. It points inward (and grows inward as well as downward) to define the eventual apical foramen as well as form the root sheath over each root defined by the inward growth of the epithelial diaphragm.
What does its downward growth leave behind and what does it form?
The epithelial root sheath (of Hertwig). This forms the overal shape (morphology) of the root.
What must be initiated before root formation can begin? Why?
Eruption. To make room within the bony crypt the tooth has developed in.
The cells of the IDE induce the pulp to differentiate into what cell type?
Odontoblasts
these resulting cells stimulate the overlying IDE to become ameloblasts?
Yes
How is cementum formation initiated?
The epithelial root sheath breaks down allowing the surrounding CT cells to contact the dentin layer. Cementoblasts form and start to secrete cementum to cover the dentin.
What is an epithelial rest?
A remnant “island” of epithelial root sheath following its dissolution.
What cells are responsible for forming cementum?
Cementoblasts.
What process is responsible for the formation of a multi-rooted tooth?
The inward growth of a projection from the epithelial diaphragm.
What is a bony compartment as opposed to a bony crypt?
A bony compartment is the space within the alveolar bone process in which the primary tooth develops. The term bony crypt refers to a similar space but contains the secondary tooth.
What are the three phases of eruption?
1. Pre-eruptive phase; 2. Prefunctional eruptive phase; 3. Functional eruptive phase.
What occurs in the first phase to the bony compartment or crypt? The ameloblasts?
Marked bone remodelling of the bony compartment/crypt occurs. The ameloblasts of the reduced enamel epithelium become squamous-like at the cuspal areas.
List the 4 major events that occur during the pre-functional eruptive phase.
1. Root formation begins; 2. The tooth moves toward the oral cavity within the compartment/crypt to make room for the developing root; 3. The tip of the crown of the tooth penetrates the fused epithelial layers entering the oral cavity; 4. The tooth continues to erupt until it contacts the opposing crown (intraoral occlusion).
What is the eruptive pathway?
An inverted triangle of tissue from the oral cavity to the eruptive location of the bony compartment/crypt. The blood and nerve supply degenerates in this region that will become the pathway for the erupting tooth.
What must be broken down for this pathway to enlarge?
The roof of the bony compartment/crypt must be eroded by osteoclasts. Macrophages release hydrolytic enzymes breaking down overlying tissue in the eruptive pathway.
What tow epithelial membranes fuse prior to eruption?
The reduced enamel epithelium covering the crown of the erupting tooth and the overlying oral epithelium.
From where does the periodontal membrane grow?
The PDL develops from a membrane of collagen fibers that begin to form at a growth center lateral to the lower end of the developing root.
Are the initial fibers contained within it oriented?
Fibers within the periodontal membrane are not initially oriented.
What is eventually formed by these fibers in this region?
The principal fiber groups of the periodontal ligament.
What is the alveolar bone septum?
The thin bony septum that separates the bony compartment of the primary tooth from the bony crypt of the secondary tooth.
During which phase is it formed?
During the prefunctional eruptive phase.