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28 Cards in this Set
- Front
- Back
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Cementum
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poorly calcified tissue that lines the root surface
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Functions of the periodontium
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Support/attachment of dentition
Eruption Proprioception Biological Seal |
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How does periodontium attach dentition?
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via a gomphosis type of joint
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primary cementum
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formed before eruption and occlusal function
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secondary cementum
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formed after eruption on the apical 2/3 of the root in response to occlusal function
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radicular cementum
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formed on the root, therefore will always be fibrillar too
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Coronoal cementum
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formed on the crown, therefore will always be non-fibrillar too
Seen on cervical third of pedo teeth as well as molars of cows |
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acellular cementum
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lacks cementocytes
the 1st true cementum formed on the root when this type is present on the root, the cementum will have fibers When present on the crown, will NOT have fibers |
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Will fibers be present if acellular cementum is present on roots?
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Yes
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Will fibers be present if acellular cementum is present on crown?
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No
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Cellular Cementum
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contains cementocytes
found exclusively on the root, 100% of the time contains extrinsic Sharpey’s Fibers from the PDL this type is formed throughout life, especially in the apical 1/3 of the root |
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What type of cementum is formed throughout life
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Cellular
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fibrillar Cementum
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has extrinsic fibers from the PDL
found only in root cementum |
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afibrillar Cementum
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Lacks extrinsic fibers from the PDL
found only in coronal cementum |
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Function of HERS
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induces odontoblast differentiation in root
determines root morphology inner layer of HERS makes Intermediate Cementum remnants of outer HERS form the Rests of Malassez |
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intermediate cementum
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found between dentin and acellular cementum
product of epithelial cells of inner HERS NOT a product of ectomesenchyme Therefore not a true cementum Has Type IV Collagen and Amelogenin proteins to induce acellular cementum |
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acellular fibrillar cementum
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1st true cementum
Gets laid down on root surface in response to Amelogenin-related proteins in Intermediate Cementum |
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cellular fibrillar cementum
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cementocytes trapped in matrix w/ their processes oriented towards the PDL for vascular supply
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affected cementum
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very porous type of cementum (the least mineralized)
contaminated by bacterial products |
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Protein Component of Cementum
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Type-I and III collagen
extrinsic fibers come from PDL and insert into cementum |
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Resorption of cementum
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by multi-nucleated giant cells (MNGC’s) called Cementoclasts derived from monocytes
resoprtion in teeth that have become necrotic resorb cementum in the following sequence 1.Acidification 2. Demineralization 3. Neutralization 4. MMPs break down protein components |
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What is the sequence of cementum resorbtion
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1. acidification
2. demineralization 3. neutralization 4. matrix metalloproteinases (MMP’s) break down the protein components |
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Orthodontic Movement
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On bone side, PDL fibroblasts sense pressure and secrete PGE-2
Causes monocytes to differentiate into osteoclasts for bone resorption On cementum side, cementoblasts don't sense pressure so no resorption |
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CEJ variations
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60% of population have cementum overlapping enamel at CEJ
30% of population has butt joint 10% of population has gap |
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Enamel Projections
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Results from failure of ameloblasts to stop amelogenesis
Most common site is lingual surface of Maxillary lateral incisors Second most common site is furcations of Maxillary molars There is increased risk for localized attachment loss because epithelial cells cannot resist inflammation |
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Enamel Pearls
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Enlarged areas of enamel formation occurring on root surface near CEJ
Due to localized failure of HERS to form so cementogenesis can proceed |
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Cementicles
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result from the reactivation of cell Rests of Malassez that secrete Amelogenin.
Results in ectopic acellular cementum formation. |
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hypercementosis
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excessive deposition of cellular cementum in the apical 1/3 of roots.
seen in the elderly and in Paget’s Disease. teeth remain vital. |
