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connective tissue structure with its stratified squamous epith.
Periodontium
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attaches the teeth to the maxilla and mandible.
Periodontium
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provides a continually adapting structure for the support of the teeth during functions.
Periodontium
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2 mineralized CT of Periodontium
Cementum and alveolar bone, Fibrous Connective Tissue, perfodontal ligament and lamina propia.
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Periodontium forms a specialized fibrous joint called
Gomphosis
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Periodontium DIVIDED INTO 2 based on function
Gingival Unit, Attachment Apparatus
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consisting of free gingiva and alveolar mucosa
Gingival Unit
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4 tissues of periodontium
Cementum, PDL, Alveolar bone, gingiva
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cementum, periodontal ligament and alveolar process
attachment apparatus
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the tooth root is attached to the alveolus (bony socket) by periodontal ligament.
attachment apparatus
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-hard tissue with a calcified intercellular substance covering the anatomical roots of Teeth
cementum
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this ligament is a complex, soft CT containing numerous cell, blood vessel, nerve fibers and ground substance.
PDL
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-Thin of compact bone with many openings. -part of the maxilla and mandible - Supports the sockets
alveolar process
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inner wall of bony socket. consists of thin lamella of bone that surround the root of the tooth and gives attachment to Sharpey's Fibers.
alveolar bone proper
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Which surrounds the alveolar bone proper and support the socket.
supporting alveolar bone
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is a hard avascular connective tissue that covers the roots of teeth
cementum
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thin layer of hard dental tissue covering the anatomic roots of teeth formed by cells known as cementoblasts, which develop from undifferentiated mesen-chymal cells in the connective tissue of the dental follicle.
cementum
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light yellow and slightly lighter in color than dentin. avascular highest fluoride content of all mineralized tissues
cementum
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formed continuously throughout life because as the superficial layer of cementum ages, a new layer of cementum is deposited to keep the attachment intact.
cementum
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dull surface more permeable than other dental tissues softness and the thinness at the cervical portion
cementum
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thickest in the apex and inter-radicular areas of multirooted teeth
cementum
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cementum 10 to 15 um in the
cervical areas
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cementum 50 to 200 um (can exceed > 600um)
apically
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organic matter + water percentage cementum collagen polysaccharides
50-55%
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inorganic or mineral content hyddroxyapatite crystals cementum percentage
45-50%
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cells in the cementum
cementocytes
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Cells of cementum that are embedded in the calcified matrix within cementum doesnt have the capbility to form cementum
cementocytes
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formative cells of cementum in the surface of cementum
cementoblast
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cementocytes shrink and stay in
lacunae
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process of forming cementum happends during root development stage of tooth
cementogenesis
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2 steps in forming cementum
matrix formation, mineralization
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Embryonically, cells are derived from the dental sac or follicle (from ectomesenchyme)
cementoblast
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UMC from PDL may Differentiate into
cementoblasts
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(Extension of the inner and outer dental Epithelium) forms and grows apically
Hertwig's epithelial root sheath (HERS)
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sends inductive signal to ectomesen-chymal pulp cells to secrete predentin by differentiating into odontoblasts. Root dentin forms.
HERS
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Hyaline layer of Hopewell-Smith also known as
intermediate cementum
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not formed by cementoblast, but he rtwigs epithelial rooth sheath
Hyaline layer of Hopewell-Smith (Intermediate Cementum)
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cementoblast came from
dental sac or dental follicle
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uncalcified matrix of cementum lined by cementoblast is called
cementoid
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Connective tissue fibers from the PDL are embedded in the cementum and serve to attach tooth to surrounding bone (Bone bundle) arwe called
sharpeys fibers
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collagenous principal fibers of the periodontal ligament embedded in both cementum and alveolar bone to attach the tooth to alveolus.
sharpeys fibers
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Organic portion of cementum composed of
collagen, matrix
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When thin layer of cementoid is formed, mineral salts from the tissue fluid of PDL is deposited as HA crystals along the collagen fibers.
Organic portion of cementum composed of
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Proteins - Ground substance - Water - Non-collagenous proteins Produced by cementoblasts or fibroblasts
matrix formation
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incremental lines of salter are
hypermineralized
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cementum They are hypermineralized area with less collagen fibers and more ground substance
Incremental Lines Of Salter
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roles of cementum 4
covers and protects the root dentin (covers the opening of dentinal tubules), provides attachment of the periodontal fibers, reverses tooth resorption, Compensates for tooth attrition
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living tissue that does not incorporate cells into its structure and usually predominates on the coronal half of the root
Acellular layer of cementum
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contains cementoblasts (inside the lacuna) and is often formed on the apical half.
Acellular layer of cementum
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(primary cementum)
acellular
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(secondary cementum)
Cellular Cementum
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Represents cementum that is formed before the tooth is established in occlusiom
Primary Cementum
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Represents all the cementum that is formed after the tooth comes in occlusion. • Continuously forms all through out life.
Secondary Cementum
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Cementum is more resistant to resorption: Important in permitting orthodontic tooth movement
true
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3 classification of cementum
Presence or absence of cells, Origin of collagenous fibers of the matrix, Prefunctional and functional
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cementum Collagen fibers of Organic matrix is derived form 2 sources:
Periodontal ligament (Sharpey's fibers), Cementoblasts
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derived from PDL. same direction of the PDL principal fibers i.e. perpendicular or oblique to the root surface
Extrinsic fibers
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derived from cementoblasts. Run parallel to the root surface and at right angles to the extrinsic fibers
Intrinsic fibers
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The area where both extrinsic and intrinsic fibers is called
mixed fiber cementum
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• First cementum • Primary cementum • Acellular • Before PDL forms • Cementoblasts • 15-20um
Primary acellular intrinsic fiber
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Located in cervical half of the root and constitutes the bulk of cementum
Acellular Extrinsic Fiber Cementum (AEFC-Primary Cementum)
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• Covers 2/3rds of root corresponding with the distribution of primary acellular cementum • Principal tissue of attachment • Function in anchoring of tooth • Fibers are well mineralized
Acellular Extrinsic Fiber Cementum (AEFC-Primary Cementum)
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cervical enamel • Forms the coronal cementum
Acellular afibrillar
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extrinsic fibers coming from
sharpeys fibers
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Cementum that normally fills the resorption lacunae • Contains cementoblasts and collagen fbers produced by cementoblasts.
Cellular Intrinsic fiber cementum
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Cementum that is found at the apical third of the root, apices and furcation areas of multi-rooted teeth.
Cellular Mixed fiber cementum
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It contains cellular components and collagen fibers derived from cementoblasts and PDL
Cellular Mixed fiber cementum
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Cementum overlaps enamel
60%
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Cementum just meets enamel
30%
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Small gap between cementum and enamel
10%
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4 signs of aging cementum
Smooth surface becomes irregular due to calcification of ligament fiber bundles, Continues deposition of cementum occurs with age in the apical area., Cementum resorption. reversal lines, Resorption of root dentin occurs with aging which is covered by cemental repair
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Calcified ovoid or round nodule found in the PDL • Single or multiple near the cemental surface • Free in ligament; attached or embedded in cementum • Aging and at sites of trauma
cementicles
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occurs at or apical to the CEJ.
roor caries
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soft, progressive lesion that is found anywhere on the root surface that has lost its connective tissue attachment and is exposed to the environment.
root caries
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Demineralisation is approximately twice as rapid on root surfaces as on enamel
root caries
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most common reasons for root caries occurrence is
gingival recession
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apical migration of marginal gingiva
gingival recession
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FORMATION AND PROGRESSION OF DENTAL CARIES increased risk for root caries among individuals with 3 reasons
exposed root surfaces, gingival attachment loss, deep pocket probing depths.
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Soft, specialized connective tissue situated between cementum and the alveolar bone lining the socket.
PDL
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bacterial organism that cause dental caries in ENAMEL
strepto mutans
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bacterial organism that cause dental caries in DENTIN
lactobacilli
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bacterial organism that cause dental caries in ROOT
actinomyces
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It is a hard avascular connective tissue that covers the roots of teeth
PDL
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5 FUNCTIONS OF PDL
Supports teeth in their sockets at the same time permitting them to withstand considerable forces of mastication., formative, nutritive, sensory, regulation of pdl width
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resorptive cells of pdl
osteoplasts
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intercellular substances of pdl
fibers, ground substances, blood vessels nerves and lymphatics
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one component of PDL you dont see in other structure
epithelial cells
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epithelial cells of pdl
remnants of the epithelial root sheath of Hertwig
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2 kinds of PDL fibers
Gingival fibers, Alveolodental fibers
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PDL help attached gingiva tp the tooth
Gingival ligaments
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attached to the cementum to the lamina propria
dentogingival fibers
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originate from the tip of alveolar bone to the lamina propria
alveologingival group
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fibers that goes around the tooth on the cervical region forms a band help bind gingiva to prevent from getting freeid out of tooth
circular group
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originate from cementum pass beyond tip of alveolar bone to insert into periostium of alevolar bone
Dentoperiosteal group
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only type of fiber attached from one tooth to another tooth in the gingival region attached to two teeth
transseptal fibers
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one end attached to the bone and one to cementum
alveolodental ligament
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From cementum goes downward Attached to the tip of alveolar bone neck region
alveolar crest group
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Perpendicular or at right angle of the long axis of tooth
horizontal group
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Main and most numerous alveolodental ligament Attachment on the bone is higher than to other tooth Mana support during mastication
Oblique group
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Fan shape orientation of fibers at the tip of the root radiate on the apical region of root
apical group