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68 Cards in this Set
- Front
- Back
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When do primary teeth begin forming
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6-8 weeks in utero
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When do successional permanent teeth begin forming
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Between 20 weeks in utero and 10 months postnatal
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When do non-successional permanent teeth begin forming
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Between 20 weeks in utero and 5 years postnatal
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What causes the increase in size and number of teeth
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The increase in jaw size
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What are the CT components of the tooth
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dental papillae & dental follicle
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What is the epithelial component of the tooth
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The enamel organ
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Enamel Organ
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Derived from the epithelium of Maxillary and Mandibular Processes from Branchial Arch 1
determines the shape of the crown initiates development of the root assists in eruption of the tooth |
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What are the stages of tooth development
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dental lamina = initiation of development
- bud stage = proliferation of cells - cap stage = proliferation of cells - bell stage = morphodifferentiation (change in shape) & histodifferentiation (change in tissues) - crown stage = apposition of calcified tissues |
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Dental Lamina
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Initial stage of tooth development
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Bud stage
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Stage of tooth development where there is proliferation of cells
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Cap stage
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Stage of tooth development after bud stage where there is further proliferation of cells
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Bell stage
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Stage of tooth development after cap stage where there is morphodifferentiation and histodifferentiation
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Morphodifferentiation
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Change in shape
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Histodifferentiation
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Change in tissue
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Crown stage
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Stage of tooth development after bell stage where there is apposition of calcified tissues
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What is the first enamel organ to develop
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Anterior mandible
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When does the 2nd permanent molar start development
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1st year postnatal
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When does the 3rd permanent molar start development
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5 year postnatal
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What occurs if the dental lamina fails to degenerate
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You result in supernumerary teeth
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Epidermal Growth Factor
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EGF
Inhibits mesenchyme and stimulates epithelial proliferation that leads to formation of dental lamina retinoids & Vitamin-A are suspected to be involved in the embryo, EGF is made by osteogenic, chondrogenic, odontogenic cells in the embryo, EGF is made by osteogenic, chondrogenic, odontogenic cells |
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Vit A deficiency in fetus
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May adversely affect formation of enamel and dentin tissues and cells due to it's involvement with Epidermal Growth Factor in the formation of dental lamina
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Which tissue is dominant before bud stage?
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Epithelium
Therefore, Odontogenic epithelium initially induces the differentiation of ectomesenchyme |
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Which tissue is dominate after bud stage
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Ectomesenchyme
Therefore, ectomesenchym reciprocates and determines the fate of the epithelium |
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What occurs if you put odontogenic epithelium into mesenchyme of some other area (like arm) early in tooth development
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You'll get a tooth forming in the arm because the epithelium is what dictated tooth formation at that point in time
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What would happen if you took away the odontogenic epithelium from the stomadeum and leave only mesenchyme later in the tooth development
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Tooth would still form in the mouth because the ectomesenchyme is what dictated tooth formation at that time
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Inner Enamel Epithelium
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Later becomes ameloblasts that will form enamel
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Cervical Loop
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Gives rise to HERS and Diaphragm which gives rise to root formation
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Hertwigs Epithelial Root Sheath
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Gives rise to root formation
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Dental Papilla
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Derived from neural crest ectomesenchyme
Cells closets to IEE gives rise to Odontoblasts Cells in the middle gives rise to fibroblasts of pulp |
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Dental Follicle/Sac
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Gives rise to fibroblasts of PDL
Gives rise to cementoblasts that will form cementum of root Gives rise to osteoblasts that will form supporting alveolar bone |
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Permanent Tooth Anlage
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Development of the second dental lamina forming the successional tooth bud
Forms lingual to the primary tooth |
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What causes establishment of the crown shape?
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Initially primary and secondary enamel knots
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What do permanemt molars arise from
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They don't arise from anlage because they are not successional
They form from distal extension of dental lamina called lateral lamina |
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Stratum Intermedium
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Demonstrates alkaline phosphatase activity
Indication of mineralization |
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Stellate Reticulum
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Secretes GAGs to attrack water into the enamel organ to push cells apart
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When does bud stage end
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When dentinogenesis begins
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Membrana Preformative
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Thickened basement membrane between inner enamel epithelium and dental papilla prior to dentinogenesisi
Induces the dental papilla to differentiate into odontoblasts |
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What induces the dental papilla to differentiate into odontoblasts?
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Membrana Preformativa
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What are the stages of ameloblastic life?
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Morphogenic
Differentiation/Organizing Crown/Secretory/Apposition/Formative Maturation Protective Desmolytic |
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Morphogenic State
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1st stage of Ameloblastic life
start making the shape of the tooth at the end of Cap Stage IEE cells are cuboidal w/ central nucleus & scattered mitochondria enamel organ & dental papilla form the Enamel Knot |
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Differentiation / Organizing Stage
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Second stage of Ameoblastic Life
IEE cells are elongating w/ organelles migrating basally ready to become ameloblasts to secrete proteins IEE cells induce its adjacent neighbors in the dental papilla to differentiate into odontoblasts |
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Crown Stage
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3rd Stage of Ameloblastic Life
REE forms dentinogenesis formation of early enamel matrix |
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Maturation Stage
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4th stage of Ameloblastic Life
immediate mineralization of the previous layer of enamel |
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Protective Stage
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5th stage of Ameloblastic Life
ameloblasts secrete an amorphous substance to make their own basement membrane they attach to the enamel surface via hemidesmosomes prevents the surrounding CT cells from becoming cementoblasts and depositing cementum onto the enamel surface |
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Desmolytic Stage
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6th and Final Stage of Ameloblastic Life
REE begins to proliferate REE induces atrophy of the surrounding CT REE secretes enzymes to digest its way through the CT for eruption REE will later contribute to the formation of the Junctional Epithelium |
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Crown Stage
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GAG's in Stellate Reticulum breaks down and can no longer bind to water therefore Stellate Reticulum begins to collapse
This allows IEE and OEE to start to approach each other Dentinogenesis induces amelogenesis Prepares for eruption |
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Mantle Dentin
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earliest dentin that gets laid down
located nearest the DEJ it is always Primary Dentin stains w/ silver contains large Korff’s Fibers |
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Circumpulpal Dentin
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gets laid down after Mantle Dentin
located nearest the pulp can be Primary Dentin if it was laid down before the tooth finished formation can be Secondary Dentin if it was laid down after the tooth finished formation does not stain silver |
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Primary Dentin
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laid down before the tooth finished formation
can be Mantle or Circumpulpal located in most of the crown and 2/3 of the root |
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Secondary Dentin
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laid down after the tooth finished formation
can never be Mantle Divides into secondary regular and irregular dentin |
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Secondary Regular Dentin
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laid down after the tooth finished formation
has a uniform distribution w/ parallel dentinal tubules |
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Secondary Irregular Dentin
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laid down after the tooth finished formation
has localized non-uniform distribution w/ un-parallel dentinal tubules AKA Tertiary Reparative Dentin |
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Which tissue has a lag phase between being laid down by the cells and mineralization?
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Dentin has a lag phase
Enamel does not (it immediately begins to resorb and mineralize) |
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Ruffled Cells
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Ameloblasts that still have their Tomes Processes
responsible for depositing Ca++ into the matrix have leaky proximal ends & tight distal ends |
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Which cells are responsible for removing proteins & water
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Smooth Ameloblast Cells
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Smooth Cells
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Ameloblasts that have lost their Tomes Processes
Responsible for removing proteins & water have tight proximal ends & leaky distal ends |
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Which cells are responsible for depositing Ca++ into the enamel matrix?
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Ruffled Cells
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Primary Phase of Enamel Mineralization
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First 30% of mineralization that takes place as soon as the early enamel matrix is laid down
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Secondary Phase of Enamel Mineralization
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Mineralization occurs in a surface to DEJ direction
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Tertiary Phase of Enamel Mineralization
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Mineralization occurs in a DEJ to surface direction
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Quaternary Phase of Enamel Mineralization
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Mineralization occurs very rapidly
Only at a thin layer near the surface that ends up becoming the most mineralized |
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Which is the most mineralized layer of enamel?
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Thin layer near the surface
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What can cause defects in enamel mineralization
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Fever
Tetracycline Fluorosis Amelogenesis Imperfecta |
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Amelogenin
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Protein of Early Enamel Matrix
control the size & shape of the HAP crystals hydrophobic Two forms - TRAP (tyrosine rich) and LRAP (leucine rich) constitutes 90% of the early enamel matrix Gene is on X-chromosome Regulated by Vit D |
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What protein constitutes 90% of the early enamel matrix?
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Amelogenin
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Enamelin
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Proteins of Early Enamel Matrix
associated w/ the earliest layer of hypermineralized enamel at the DEJ 1 st protein secreted in amelogenesis, therefore it is found at the DEJ hydrophilic Very acidic |
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Which Protein of Early Enamel Matrix is secreted first in amelogenesis?
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Enamelin
Therefore found at DEJ |
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Tuftelin
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Proteins of Early Enamel Matrix
similar to Enamelin, but associated w/ enamel tufts |
