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59 Cards in this Set
- Front
- Back
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Function of the Periodontium
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Support and attachment of teeth in alveolar bone
Eruption and adaptation of teeth to changes in occlusion Proprioception of occlusal forces Biological seal |
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Which wear are teeth constantly migrating?
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They are migrating mesially to compensate for inadequate contact points
Also constantly erupting to compensate for occlusal wear |
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Components of Periodontium
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Cementum
PDL Alveolar bone Gingiva |
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What is the order of development of periodontium
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CPAG
Cementum PDL Alveolar bone Gingiva (epithelium, CT) |
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What is considered the CT attachment?
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They are the attachment apparatus
Cementum PDL Alveolar bone |
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What induces formation of the periodontium
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Odontogenesis
Gingiva cannot form without tooth formation inducing it |
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What are the clinical features of healthy periodontium
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Salmon pink mucosa
Keratinized epithelium for abrasive protection Gingival margin follows CEJ Biologic seal is in tact alveolar mucosa is very thin, red, un-keratinized w/ lots of BV’s |
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What are clinical features of Periodontitis
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slightly cyanotic color
supuration (oozing of pus) w/ applied pressure biological seal has been broken bacterial byproducts causes initiation of the host inflammatory response loss of teeth |
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What happens if the biological seal has been broken
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Allows bacteria to penetrate
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Supuration
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Oozing of pus
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Induction
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Idea that something signals the cells to become committed to their own path of development under the appropriate environment
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What are some inductive factors
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Soluble factors
Cell-to-cell contract Interactions with the components of Extracellular matrix seems to be the most important inductive factor |
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What is the most important inductive factor
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Interactions with the components of the extra-cellular matrix
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What is necessary to get development
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You have to have factors which act on a pluripotent cell population
Induces cellular commitment Have the right environment for those cells to execute their genetic programs |
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Ectomesenchyme
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Mesenchyme of the face
Derived from neural cress cells |
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Epithelial-mesenchymal interactions
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Necessary for formation of band, dental lamina, bud, cap, and bell stages
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What induces the oral epithelium to thicken
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Ectomesenchyme induces to thicken and invaginate down into the CT to become the dental lamina
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How is the dental lamina formed?
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ectomesenchyme induces the oral epithelium to thicken and invaginate down into the CT becoming the dental lamina
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What does dental lamina induce?
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Induces ectomesenchyme cells below to condense and become dental papilla & dental follicle
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What does IEE induce?
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induces dental papilla to become odontoblasts and secrete dentin
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What does dentin induce?
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induces IEE cells to become ameloblasts and secrete enamel
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Enamel organ
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becomes enamel, junctional epithelium, Rests of Malassez
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Dental papilla
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becomes pulp, dentin
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dental follicle
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becomes cementum, PDL, alveolar bone
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What was used to label the extracted tooth buds used to study dental follicle?
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Radioactive thymidine
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Function of HERS
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determines root morphology & anatomy
induces dental papilla cells in the root region to differentiate into odontoblasts inner layer of the HERS makes Intermediate Cementum remnants of the HERS that broke away form the Rests of Malassez |
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What does HERS induce?
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induces dental papilla cells in the root region to differentiate into odontoblasts
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What does the inner layer of HERS make
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Intermediate Cementum
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Which layer of HERS is more biosynthetically active
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Inner cell layer
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What induces the inner layer of HERS to form Intermediate Cementum
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odontogenesis
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What causes differentiation of acellular cementoblasts
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When some HERS cells undergo apoptosis
Causes layer of intermediate cementum of lift away Allows cells of dental follicle to touch intermediate cementum and differentiate into cementoblasts to create acellular cementum |
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What induces cementogensis
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amelogenin proteins seem to induce acellular cementum formation
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Emdogain
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extracted enamel matrix from fetal pigs
major inductive factor used in perio therapies paint the root surface w/ Emdogain Induces pluripotential stem cell population in the PDL to form acellular cementum |
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Epithelial Rests of Malassez
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cells that have been left over from the HERS
arranged in little “islands” on the tooth side of the PDL no known function maybe these cells are important in periodontal regeneration |
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What is the 1st type of cementum formed
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Acellular cementum
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Where do you find acellular cementum
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apical 2/3 of the tooth
It is the first to form |
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Which way are cementocyte cell processes directed?
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directed towards the PDL, the sole source of vascularity
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Extrinsic Fibers
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insert and get “trapped” into cementum
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Intrinsic Fibers
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go around the tooth, but never extend into the PDL
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Sharpey’s Fibers
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insert into alveolar bone
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PDL
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polarized
heterogenenous highly metabolic tissue contains fibroblasts for the remodeling & formation of new PDL fibers contains neurovascular bundles contains osteoblasts w/ Sharpey’s Fibers inserting into periosteum |
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Which way do fiber bundles run in PDL
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run from a coronal to apical direction
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Intermediate Plexus
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cementum & bone fibers exist separately and then meet in the middle of the PDL
**does not exist in humans |
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How does alveolar bone form
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by mesenchymal condensation within the dental follicle
Woven bone initially forms It is remodeled by the action of “cutting cones” into mature lamellar (Haversian) bone |
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What occurs in the absence of odontogenesis
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alveolar bone fails to develop
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What occurs if you put the whole entire intact tooth bud w/ its dental papilla & follicle still intact in the anterior chamber of mice
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you’ll get a whole tooth + PDL + bone forming in the eye
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What occurs if you combine only the enamel organ & dental papillae WITHOUT the follicle
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no bone formation in the mice eye
Therefore, cells that form alveolar bone reside in outer layer of dental follicle |
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Where do the cells that form alveolar bone reside?
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Outer layer of dental follicle
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what if you recombine mouse molar papillae w/ chicken epithelium and put it into the eye?
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you get a primitive tooth w/ a single cusp
That means chickens have amelogenin gene too It is just not expressed because birds cannot fly if they have dense tissues like enamel |
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Epithelial cuff
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Eruption of the tooth causes the oral epithelium to fuse with the REE creating the cuff that the crown will erupt through
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What is oral epithelium continuous with?
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Sulcular epithelium
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Primary Attachment
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inner layer of the REE (reduced ameloblasts) will attach to the surface of the tooth like a BM via hemidesmosomes
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Secondary Attachment
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REE cells degenerate and give rise to successive generations of Junctional Epithelium + Oral Epithelium
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Biologic Seal
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Secondary Attachment
Two Basement Membranes of Junctional Epithelium and gingival fibers - one attached to the tooth surface - another attached to the underlying CT 2mm in width |
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gingival fibers
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CT attachment
holds the gingiva securely around the neck of the tooth 1.5mm long |
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Junctional Epithelium length
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0.5mm
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Gingiva fibers length
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1.5mm
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Biologic Width
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The distance established by the junctional epithelium and CT attachment to the root surface of a tooth
2.0mm (it’s the JE + gingival fibers) establishes the biologic seal |
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Passive Eruption
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the progressive apical migration of the junctional epithelium with age in the absence of perio disease
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