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23 Cards in this Set
- Front
- Back
Exfoliation
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Progressive and discontinuous resorption of the deciduous roots by odontoclasts in the absence of inflammation
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Why is exfoliation necessary?
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Because adults cannot effectively masticate with tiny baby teeth, therefore they must be shed to allow for larger teeth to come it
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What dictates the pattern of root resorption?
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Dictated by pressure exerted by the erupting sucedaneous totth
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What is exfoliation characterized by?
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Alternating cycles of resorption and healing, leading to a net loss of root structure
Odontoclasts resorb way more tissue than needed to relieve the pressure Immature Cellular cementoid is deposited with patchy spots of mineralization |
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What is the pattern of root resorption in anterior teeth?
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Resorption begins at the lingual edge of the primary root
Some root structure remains at the time of exfoliation Resorption never reaches CEJ Only cementum and dentin are resorbed Odontoclasts DO NOT migrate into pulp cavity Pulp and dentin are left un-touched |
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Where does resorption begin in anterior teeth?
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Lingual edge of the primary root
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How far does resorption reach in anterior teeth?
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Never reaches CEJ
Only cementum and dentin are resorbed Enamel is left un-touched Does not migrate into pulp cavity therefore pulp and dentin left un-touched |
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What are patterns of root resorption in posterior teeth?
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Resorption begins on primary lingual root so secondary tooth can move underneath in between the roots during pre-eruptive phase
Second phase is when resorption occurs on inner edges of all roots No root structure remains at time of exfoliation Resorption can reach past the CEJ, resorbing cementum, dentin and some enamel Odontoclasts often migrate into pulp cavity to eat tooth from inside out, leaving shell of enamel at time of exfoliation |
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How far does resorption reach in posterior teeth?
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Reaches past the CEJ resorbing cementum, dentin and some enamel
Odontoclasts also migrate into pulp cavity to eat tooth away from the inside out |
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Where does resorption begin in posterior teeth?
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First on lingual root of primary tooth to allow for secondary tooth to move underneath
Then resorption on inner edges of all roots to adjust for the secondary crown |
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What is the pattern of root resorption during excessive masticatory forces?
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Masticatory forces are too much for retained primary tooth
Pressure on the roots of primary tooth causes resorption of its roots Leads to exfoliation |
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What are some resorption trends
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Mandibular teeth exfoliate before maxillary teeth
Girls exfoliate before boys Dentin resorbs the fastest because it has tubules increasing surface area Enamel resorbs the slowest because it's comprised mainly of minerals taking the longest to dissolve |
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Which tissue is fastest to resorb?
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Dentin resorbs the fastest
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Which arch exfoliates first?
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Mandibular exfoliates before maxillary teeth
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Which tissue is slowest to resorb?
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Enamel because it's comprised mainly of minerals taking the longest to dissolve
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What are some clinical abnormalities during exfoliation?
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Retained primary teeth because of absence of secondary tooth underneath
Retained roots doe to piece of primary root that never experience resorptive pressures. This leads to ankylosis in alveolar bone |
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What are the molecular signals that induce clast activity?
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Pressure on root/bone stimulate dental follicle cells to secrete Epidermal Growth Factor (EGF) which affects Stellate Reticulum to upregulate production of IL-1a and TGF-B1
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TGF-B1
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Stellate Reticulum is stimulated by EGF to produce TGF-B1
It upregulates production of IL-1a It upregulates dental follcle cells' expression of IL-1a receptors It recruits monocytes into the area through chemotactic factorsr |
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IL-1a
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Stellate Retciulum is stimulated by EGF to produce IL-1a
It stimulates the dental follicle cells to produce Colony Stimulating Factor-1 to make even more CSF-1 (autocrine function) and recruit macrophages to clump and form osteoclasts/odontoclasts (paracrine function) |
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What is the function of Colony Stimulating Factor-1
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It is produced by the dental follicle by stimulation from IL-1a
It has a paracrine function to recruit macrophages to clump and form osteoclasts and odontoclasts Also has a autocrine function to make even more CSF-1 |
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What is the function of Epidermal Growth Factor?
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It is secreted by dental follicle cells in response to pressure on the root
It directly affects IL-1a production by stimulating Stellate Reticulum to produce more It indirectly affects IL-1a by stimulating stellate reticulum to upregulate production of TGF-B1, which also upregulates production IL-1a |
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Characteristics of Clast Cells
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Huge
Multi-nucleated Phagocytic Comprised of 50+ fused Macrophages Ruffled border and apical cisterna increaes resorptive capacity Tons of lysozomes in acidic cytoplasm |
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What is the sequence of Clastic Resorption?
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1. Clast begins resorption by creating Howship's Lacunae sealing off acidic environment
2. Lysozomes release protons and acid phosphatase to dissolve inorganic crystals first 3. Demineralization exposes the protein scaffold that HAP gets deposited on 4. Lysozomes release proteases/collagenases to break protein components 5. Clast cell phagocytizes bits of collagen to complete collagen break down 6. HAP crystals get dissolved, but are not phagocytized |