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117 Cards in this Set
- Front
- Back
Enamel (general characteristics)
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Hardest, most durable tissue. 96% inorganic, 1% organic, 3% water. Calcified hydroxyapatite makes up 65% inorganic, rest is carbonate, magnesium, potassium, sodium, fluoride.
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Enamel (general)
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avascular, no living cells. No additional enamel formed. REE adheres and forms cuticle (Nasmyth’s Membrane), which can be calcified and cause intrinsic staining.
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Enamel color
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variety of shades of bluish white (translucent). Most clear at incisal edge. Deciduous teeth are more opaque white
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Tome’s processes
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form enamel matrix at incisal edge and progress cervically.
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Enamel apposition
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at formation, mostly organic, then as tome’s processes secrete matrix, rest of ameloblast pumps hydroxyapatite into forming enamel, which begins mineralization.
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Enamel mineralization
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occurs from the inside-out, mineralized first by DEJ. Ameloblasts continue to pump calcium hydroxyapatite as it withdraws from organic matrix. When ameloblasts done with enamel, they lay down cuticle and become part of REE.
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Enamel rods
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structural units. Extend entire length from DEJ to surface. Roughly perpendicular to DEJ, but some curvature. Key-hole shaped (interlocking adds strength)
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Interprismatic region (interrod)
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forms outer portion of enamel rod, between individual enamel rods. Matrix is less mineralized and different crystal orientation
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DEJ is scalloped
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(concave toward enamel) for strength.
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Lines of Retzius
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growth lines. Appear as cross striations (like concentric tree rings). Help form perikymata and imbrication lines. Caused by alteration in enamel formation (trauma, disease, high fever)
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Neonatal line
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formed by traumatic event of birth.
Primary teeth and 1st perm. Molars |
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Enamel spindles
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projections of dentinal tubules that cross DEJ before mineralized (usually cusps or incisal edge)
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Enamel tufts
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brush-like formed by abnormal crystallized enamel. By DEJ
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Enamel Lamallae
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partially calcified vertical faults from DEJ to surface (usually cervical enamel)
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Caries progress more rapidly in ___
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enamel tufts and enamel lamella because less mineralized
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Gnarled enamel
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very tough, wave-like.
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Enamel destroyed by __
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odontoclasts (shedding teeth). Not destroyed under normal processes. Enamel repair only through remineralization.
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Enamel etching
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interrod is partially dissolved, so dental materials bond better (sealant, composite)
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Changes to enamel with age (normal)
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attrition (can force formation of secondary dentin), decreased permeability,
increased fluoride content (less permeable and more fluoride mean stronger). |
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More decay on __ area in older patients
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cervical (Class V)
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Caries penetration of enamel
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once through enamel, caries spread laterally into dentin. Enamel can break because dentin support is lost.
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Fluoride
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systemic (fluorosis ); topical
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Dentin (general characteristics)
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second hardest tissue. 70% inorganic (20% organic, 10% water).
Dentin covered by enamel or cementum. Makes up bulk of tooth. Contains NO cells, but does have cellular extensions of odontoblasts |
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Dentin color
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yellowish. Gives teeth color.
Can be stained if exposed. Very porous (smokers, coffee, etc) |
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Odontoblastic processes
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cellular extensions of odontoblasts up the dentin toward CEJ
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Exposure of dentin in oral cavity
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abnormal
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Deninogenisis
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process of predentin formation. Continues through life as long as odontoblasts are vital
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Predentin
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laid down by odontoblasts (outer cells of dental papilla). Layer of non-mineralized dentin remains and lines outer pupal wall
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Maturation of dentin
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Primary: crystals form globules in collagen fibers. Secondary: strengthens crystal
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Globular dentin
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primary & secondary mineralization, complete fusion
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Interglobular dentin
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only primary mineralization has occurred, and not fuse completely. Slightly less mineralized. Near DEJ
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Dentinal tubules
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“holes” in the dentin; extend from pulp wall to DEJ/DCJ. Contain odontoblastic processes and afferent sensory axon (PAIN only stimulus). New teeth: process extends all the way. With age, it draws closer to pulp (decreased sensitivity, caries progression down tubule)
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Hydrodynamic hypersensitivity theory
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plug holes in dentin so fluid doesn’t move = no pain
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Types of dentin (by mineralization)
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peritubular: walls of dentin tublues. Most mineralized. Intertubular: between tubules, less mineralized.
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Types of dentin (by location)
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Mantle: outer layer; 1st formed. More mineralized. Circumpupal: bulk of dentin, less mineralized. Pre-dentin: unmineralized found in new teeth next to pulp
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Types of dentin (by chronology)
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Primary: formed before apical foramen closes. Secondary: formed after apical foramen closes (made throughout life). Tertiary: reparative; rapid resonse to injury; from pulp outward, more irregular tubules. Sclerotic: when odontoblastic processes withdraw, tubules fill with calcium salts (complete mineralization, sealed)
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Lines of Von Ebner
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imbrication lines. incremental growth lines. run perpendiular to dentinal dubules seen under high magnification.
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contour lines of Owen
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disturbances in formation of dentin. formed when Von Ebner form very close together. seen under lower magnification.
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Neonatal line
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pronounced contour line from trauma of birth
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Tome's Granular layer
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small, unmineralized areas of dentin, forms a band just under cementum ONLY on root surfaces. If exposed, it's sensitive to hot, cold, sweets
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dental pulp (general)
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only NON-mineralized tissue in tooth, contains odontoblasts in outer layer, rest is made up of CT and fibers (fibroblasts). Blood, nerves, and lymph enter through apical foramen.
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Functions of pulp
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formative: by odontoblasts. sensory: any stimulation is felt as PAIN. other sensations due to PDL. Nutritive: nutrition to odontoblasts, which extend to dentin. Defensive: WBCs used as inflammatory response. Only place to swell is at apical foramen. production of secondary, reparative, and sclerotic dentin.
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Odontoblasts
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found next to dentin. CANNOT reproduce after differentiation.
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Fibroblasts
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Form collagen fibers; most numerous cells in pulp. With age, number decreases while the number of fibers increase.
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Undifferentiated mesenchymal cells
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Differentiate into different kinds of cells depending on demand.
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Defensive cells
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rid body of dead bacterial cells. Macrophages engulf particles and destroy them. B-lymphocytes (purpose unknown).
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Also present in pulp
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Blood and lymphatic (number decreases with age). Nerves (enter through apical foramen) form a dense network; nerve cell bodies in odontoblast cell layer interspersed between cells
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odontoblastic layer (cell zones/layers)
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outermost layer next to dentin. Cell bodies of afferent axons are located between odontoblasts.
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cell free layer (cell zones/layers)
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appears empty, however contains numerous nerves and blood vessels
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cell rich layer (cell zones/layers)
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extensive vascular system with many cells. primary cell is fibroblast.
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pulpal core (cell zones/layers)
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except for location, very similar to cell-rich zone.
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accessory canals
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extra openings on sides of root that connect pulp to PDL. May contain blood, nerves, lymph. More common in molars.
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pulp stones (denticles)
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calcified masses of dentin found in pulp; usually irregular; can be seen on x-rays. Grow larger with age, can form around blood clots, dead cells, collagen. Defense mechanism. If large, can interfere with RC treatment.
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Pulp Changes with Age
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number of cells decreases, number of blood and lymph decreases, pulp size decreases, number of fibers INCREASES (becomes fibrotic)
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Dentin Changes with Age
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tubules narrow, odontoblastic processes retract (less sensitivity)
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Periodontium
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Supporting soft and hard tissues that maintain teeth in a functional state. Made up of cementum, alveolar bone, periodontal ligament, gingiva.
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Cementum (general characteristics)
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covers anatomical root (tome's granular layer dentin). attachment point to fibers of PDL make surface rough (bacteria/calculus attach well, same susceptibility to decay as dentin
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Cementum (general)
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similar hardness to bone; 65% inorganic, 25% organic, 12% water. pale yellow (lighter than dentin). Avascular, no innervation. thinner cervically; thicker apically
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acellular cementum
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no cells w/in it, no embedded cementocytes. Cementocytes that form it are found in PDL (forms slowly). Cervical 2/3 of root, very thin layer covers entire root (first layer deposited)
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Cellular cementum
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contains cells, cementocytes within, apical 1/3 of root and interradicular. Layers can be added over time
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Development of cementum
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develops from dental sac (mesenchyme) after Hertwigs root sheath disintegrates.
Cementogenisis: Cementoblasts lay down cementoid. Matrix is calcified, trapped cementoblasts become cementocytes. |
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Surface of cementum
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projections on surface will attach to PDL fibers (Sharpey’s fibers while they are in cementum). Only in cellular cementum, also extensions of canaliculi that connect to PDL.
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CEJ relationship between Cementum, Enamel
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overlapping (60%)
end to end (30%) gap (10%) |
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Cementum repair
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less readily absorbed than bone. Do not continuously repair, only as result of trauma
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Acellular cementum
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primary cementum. First layer deposited on DCJ on entire root. NO embedded cementocytes. Near CEJ, cervical 1/3
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Cellular cementum
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mainly apical 1/3 and in between roots (interradicular). Form faster, so cementocytes become trapped (surrounded by lacunae).
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Lacunae
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cementocytes surrounded by it (similar to bone)
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Canaliculi
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canals radiating from lacunae. Most radiate towards PDL. Nutrient canals to receive nutrients and take waste.
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Cementocytes location
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randomly in cellular cementum, but increase closest to PDL.
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Cementoblasts
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located in adjacent PDL, which makes repair (cementogenesis) possible
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Clinical importance cementum
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can be formed continuously, and can be repaired. ONLY remodeled when damaged.
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Hypercementosis
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(cemental dysplasia) excessive formation in apical 1/3. Caused by trauma. Tooth difficult to extract.
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Ankylosis
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excessive cementum fills PDL, fuses tooth to bone. Very rare, extraction very hard.
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Cementicles
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small bodies of cementum found within PDL or surface of cementum. No clinical significance.
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Cemental spurs
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found at or near CEJ, not easily removed.
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Relationship of cementum to calculus
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when cementum is exposed, plaque and calculus attach to rough places fibers had inserted.
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Cementoossifying firbroma
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neoplasm, causes enlarged bony growths
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Alveolar bone
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(alveolar process or alveolar ridge) contains roots of teeth; divided by location (alveolar bone proper, supporting alveolar bone, combination)
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Alveolar bone proper
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(cribriform plate or lamina dura) lines tooth socket (compact bone) contains Volkmann’s canals. Sharpy’s fibers inset into this bone. Dense radiopaque line
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Alveolar crest
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most cervical rim. In health, 1-2 mm apical to CEJ
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Supporting alveolar bone
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cortical bone (compact bone on facial and lingual). BASE Trabecular bone: cancellous bone between alveolus and cortical plates. Spongy.
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Combination of alveolar and supporting
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interdental septum. Bone between adjacent teeth. Both compact bone and trabecular supporting bone
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Intraradicular septum
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bone between roots. Compact and trabecular supporting bone.
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Basal bone
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forms the body of the maxilla and mandible. More resistant to absorption.
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Development of jaw bones
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from first branchial arch. Begins as intramembranous ossification. Serves as a template. Fuses around nerves (forming canals)
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Clinical considerations Alveolar Bone
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pressure leads to resorption tension/pulling causes deposition
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Endentulous
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lose vertical dimension
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Implants
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osseous integration (fuses to bone). No PDL
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Bone Loss
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first becomes apparent in alveolar crest and interdental septum (looks fuzzy)
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Periodontal ligament (general)
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occupies space between teeth and bone. Support and maintain teeth. Prevent direct contact of tooth with bone. Shock absorber. Continuously remodel bone. X-rays radiolucent.
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Widened PDL
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abnormal increase in function
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Periodontal atrophy
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PDL not stimulated and shrinks
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Apical foramen
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blood and nerve supply enter the tooth. Carries nutrients.
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Sensory
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pain, pressure, temperature, proprioception, percussion
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Periodontal ligament developed from
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dental sac (also cementum and alveolar bone)
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Components of PDL
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fibers, ground substance, fluid, blood vessels/nerves, cells (fibroblasts, cementoblasts, osteocytes, osteoclasts, osteoblasts, donotoclasts, undifferentiated mesencymal, epithelial rests)
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Fibers of PDL
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formed by fibroblasts, made of collagen, called Sharpey’s fibers (when embedded in cementum and bone)
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Orientation of PDL fibers
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Functional tooth: fibers straight and arranged in groups. Non-functional (perio atrophy): fibers relaxed and wavy, and if placed in function again will be painful and sensitive until PDL and bone repair
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Alveodental ligament
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grouped based on orientation to tooth and related function. Resist rotational/twisting forces. When embedded in cementum or bone called Sharpey’s fibers.
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Alveolar crest group
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connect crest to cervical cementum. Resist tilting, rotation, intrusive/extrusive
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Horizontal group
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root to bone horizontally, apical to alveolar crest group. Small group. Resist tilting/rotational
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Oblique group
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diagonal. Apically from bone to cementum. Most numerous. Cover apical 2/3. Resist intrusive. Without them, constant pressure would cause resorption.
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Apical group
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located around apex. Resist extrusive
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Interradicular group
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ONLY between multi-rooted teeth. Cementum of root to cementum of other root (NO bone contact). Resist intrusive/extrusive and tilting forces.
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Interdental ligament
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(transseptal ligament) connects adjacent teeth. Coronal to alveolar crest (cementum to cementum). Maintain proximal contact, resist rotation
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Gingival fiber group
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(dentogingival ligament) supports gingiva. Circular, dentogingival, alveolar, dentoperiosteal, periosteal
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Circular fiber
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encircle tooth. DON’T touch tooth, like rubberband. Inflammation causes them to be loosened
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Dentogingival group
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connects marginal gingiva to coronal cementum. Keeps tissue close to tooth
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Alveolargingival fibers
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alveolar crest to marginal gingiva. Keeps gingiva attached to bone
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Dentoperiostal fibers
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cementum to alveolar crest. Protect PDL. attach tooth to bone
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Periosteal gingiva
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facial of alveolar crest toward gingiva. Help stippling
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Components of PDL
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many blood vessels in loose CT.
3 main sources: bottom of alveolar socket, alveolar crest, cribriform plate. Vessels from network around root with anastomes (connections) |
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Epithelial rests of Malassez
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remnants of epithelial root sheath
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Cementicles
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very small spherical calcified bodies of stray cementoblasts in PDL
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Clinical considerations PDL
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occlusal trauma causes widening of PDL (seen on x-ray between lamina dura and cementum)
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Periodontal disease targets
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soft CT fiber groups. Can’t be regenerated. Requires surgery
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Lack of use
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PDL atrophies, narrows PDL space
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