Term
| Is cementum thicker apically or cervically? |
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Definition
Apically (also thick in interradicular areas) 10-15 microns cervically 50-200 microns apically |
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Term
| What is the definition of cementum? |
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Definition
| A hard avascular connective tissue covering roots of teeth; like bone but bone is vascular |
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Term
| What are 3 roles of cementum? |
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Definition
- Covering root dentin (covering dentinal tubules)
- Site of attachment for periodontal fibers
- Compensate for resorption (maintains height lost to resorption)
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Term
| T or F: cementum resportion is abnormal |
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Definition
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Term
| How is cementum similar to bone? |
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Definition
- Lacunae w/ cementocytes within
- Canaliculi
- Incremental lines (aka resting lines) produced from continuous phasic deposition of cementum - NOT EXACTLY REMODELING, BONE REMODELS, CEMENTUM DOES NOT
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Term
| How do bone and cementum differ? |
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Definition
- Not vascularized
- Minor ability to remodel
- Resist resorption (due to lack of vascularization)
- Lacks neural component thus no pain
- 70% bone is inorganic (cementum only 45-50%)
- 2 unique cementum molecules CAP (cementum attachment protein) and IGF
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Term
| Describe the steps in the development of cementum: |
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Definition
- HERS induces underlying ectomesenchymal cells of the pulp to differentiate into odontoblasts and secrete predentin
- HERS becomes interrupted
- Ectomesenchymal pulp cells come into contact with predentin and differentiate into cementoblasts
- Cementoblasts lay down cementum
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Term
| What are 3 theories of how cementoblasts are activated to lay down cementum? |
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Definition
- Dental follicle cells may receive reciprocal signal from HERS or dentin to differntiate into cementoblasts
- HERS cells differentiate directly into cementoblasts
- Possible role of epithelial cell rests of Malassez
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Term
| What is the most common type of collagen in cementum, dentin and bone |
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Definition
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Term
From where does intermediate cementum (hyaline layer of Hopewell-Smith) originate? Where is it located? It's function? It's composition? |
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Definition
- It originates from HERS before it disintegrates; functions to seal dentinal tubules;
- found between the granular dentin layer of Tomes and the secondary cementum (origin cementoblasts)
- Mineralized greater than adjacent dentin or secondary cementum
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Term
| List properties and chemical composition of cementum |
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Definition
Pale yellow More permeable than other dental tissues 45-50% hydroxyapetite (inorganic) [bone has higher inorganic content] 50-55% collagenous and non-collagenous organic matrix proteins |
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Term
| What are three methods of classifying cementum? |
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Definition
- Presence or absence of cells
- Prefunctional and functional
- Origin of collagenous fibers of the matrix
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Term
| Where are acellular and cellular cementum most likely found and why? |
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Definition
- Acellular (primary) - found along the majority of the root; does not require cells where cementum is thin because the fluid that bathes these cells keeps it viable
- Cellular (secondary) - near apex and interradicular; found where cementum is thicker to maintain viabilitiy cellular usually overlies acellular
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Term
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Definition
Young matrix that becomes secondarily mineralized Cementoid + hydroxyapetite = cementum |
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Term
| What are two major differences between cellular and acellular cementum? |
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Definition
- Cells and no cells
- Acellular has slow growth and incremental lines are relatively close together; cellular grows fast and lines are far apart
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Term
| What are the two origins of collagen fibers in the organic matrix of cementum? |
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Definition
| Sharpey's fibers (PDL) and cementoblasts |
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Term
| Differentiate between intrinsic, extrinic, and mixed collagen fibers of cementum: |
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Definition
- Extrinisc - derived from Sharpey's fibers (periodontal ligament); perp. or oblique to root surface
- Intrinsic - derived from cementoblasts - parallel to root surface and right angles to extrinsic fibers
- Mixed - area with both intrinsic and extrinsic
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Term
| Describe the distribution of types of cementum on the root: |
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Definition
Acellular afibrillar near CEJ Acellular extrinisic: cervix to nearly whole root; inc in thickness near apex Cellular: apical 1/3 and furcations |
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Term
| Describe the OMG rule at the CEJ |
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Definition
Cementum overlaps enamel 60% Cementum meets enamel 30% Gap between cementum and enamel 10% |
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Term
| What are some consequences of aging for cementum? |
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Definition
- Becomes irregular due to calcification of ligament bundles where they attach to calcium
- Continuous deposition of cementum in apical area (+ Maintains tooth height; - blocks apical foramen)
- Cementum resorption followed by deposition creating reversal lines
- Resorption of root dentin replaced through cemental repair
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Term
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Definition
Single or multiple calcified round or ovoid nodules found in the PDL; found free in the ligament and attached or embedded in cementum; due to injury or age |
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Term
| With a loss of cementum what else is lost? |
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Definition
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Term
| Cemental repair occurs when? |
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Definition
| After resorption of root dentin or cementum due to trauma; reparative cementum restores attachment |
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Term
| What happens to cementum and alveolar bone during orthodontic movement? |
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Definition
| Cementum resists resorption so is maintained which alveolar bone resorbs and remodels to move the teeth |
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Term
| If cementum has no innervation why may a patient experience sensitivity following a scaling and root planing? |
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Definition
| If cementum is removed the dentin is exposed and can be painful |
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Term
| When does the alveolar process start developing? |
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Definition
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Term
| What are the layers of bone in the alveolar process? |
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Definition
- Bundle bone (aka alveolar bone proper) - (closest to tooth lining alveolus)
- Central spongiosa - standard bone w/ volkman and haversian canals
- Outer cortical plate - lamellar w/ haversian systems
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Term
| Describe bundle bone (alveolar bone proper). |
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Definition
- May be perforated by Sharpey's fibers of the PDL or may be just compact bone
- Sharpey's fibers would be perpindicular or oblique to the bundle bone
- Appears more radiodense because of inc. mineral content around bundles - called lamina dura in xrays
- Perforated by foramina transmitting nerves and vessels
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Term
| Where is the alveolar crest found? |
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Definition
1.5-2 mm below level of the CEJ Slanting of the crest is indicative of perio disease and bone loss |
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Term
| What happens when a tooth doesn't have an antagonist? |
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Definition
| Osteopenia, resorption of the alveolar bone, because of inactivity of the tooth |
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Term
| What are some characteristics of the PDL? |
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Definition
Thinnest midroot Thickness from .15 to .38 mm Width decreases w/ age b/c of inc. production of cementum High turnover rate |
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Term
| When does the PDL form and from what? |
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Definition
| Forms from the dental follicle shortly after the root |
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Term
| Where is acellular afibrillar cementum located and what is its role? |
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Definition
Near the CEJ Lacks collagen so it has no role in attachment May be a developmental anomaly |
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Term
| Where is acellular extrinsic fiber cementum located, what is its function, and origin of fibers? |
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Definition
Located from cervical margin to apical third Functions in anchorage Fibers originate extrinsically Principal tissue of attachment |
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Term
| What is the origin, location, and function of cellular intrinsic fiber cementum? |
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Definition
Intrinsic fibers Middle to apical third and furcations Adaptation (maintain occlusal height) and repair (cemental damage) |
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Term
| What is the origin, location, and purpose of secondary cellular mixed fiber cementum? |
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Definition
Fiber origin is intrinsic and extrinsic with extrinsic being thicker (5-7 microns) and intrinsic being (1-2 microns) Bulk of secondary cementum Located in apical portion and furcations For adaptation |
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Term
| What is the function of oxytalan fibers? |
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Definition
Regulate vascular flow in relation to tooth function Run obliquely from cementum to blood vessels Most numerous in cervical area |
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Term
| What are the purposes of the PDL? |
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Definition
- Shock absorber
- Tooth support
- Proprioception
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Term
| Which dentoalveolar fibers are most numerous? |
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Definition
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Term
| What is origin of each dentoalveolar fiber? |
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Definition
Alveolar crest group: below CE junction, downward and outward Horizontal group: apical to ACG; right angle to root Oblique group: oblique direction attaching coronally to bone Apical group: apex base of socket Interradicular group: |
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Term
| What is the origin of each gingival ligament fiber? |
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Definition
Dentogingival - cementum to f/a gingiva Alveologingival - alveolar bone to f/a gingiva Circular - completely in gingiva around neck of tooth Dentoperiosteal - runs apically from the cementum over the outer cortical plate to alv. process or vestibule (muscle) or floor of mouth Transseptal - cementum between adjacent teeth over alveolar crest |
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Term
| What is most numerous gingival ligament fibers? |
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Definition
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Term
| In terms of blood supply to the PDL, what major vessels does it originate from, and in what areas of the mouth is it most prominent? |
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Definition
Derived from the superior and inferior alveolar arteries Posterior > anterior Mandibular > maxillary |
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Term
| In terms of nervous supply to PDL, where does it originate and in which portion of the tooth does it predominate? |
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Definition
| Derived form the inferior and superior alveolar nerves and found mostly in the apical region |
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Term
| What are major characteristics of the interstitial space of the periodontium? |
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Definition
Present between fiber and containing the nerve and vascular supply Lots of ground substance here to withstand masticatory forces (70% water) Dermatan sulfate is major glycosaminoglycan |
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Term
| What happens to the PDL when funtion is reduced? |
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Definition
PDL narows and fiber bundle number and thickeness decreases Primarily due to inc. cementum deposition |
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Term
| What are the four stages of the eruptive tooth stage? |
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Definition
- Root formation
- Movement
- Penetration
- Occlusal contact
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Term
| Teeth are constantly moving in the preeruptive phase. What are the two types of movement? |
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Definition
- Total bodily movement
- One portion remains fixed and the rest moves leading to changes in the tooth germ
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Term
| What happens to the tissue directly over an erupting tooth? |
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Definition
| Blood vessels and nerves degenerate and macrophages destroy cells and fibers through hydrolytic enzymes |
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Term
| What is the gubernacular cord? And canal? |
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Definition
CT overlying successional tooth that connects with the lamina propria of oral mucosa by means of a fibrous CT that contains remnants of dental lamina; Canal widens and allows the cord to pass --> canal is seen lingual to primary teeth |
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Term
| What are the rates of intraosseous and extraosseous tooth movement |
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Definition
Intraossesous 1 - 10 microns/day Extraossesous 75 microns/day |
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Term
| What is cleidocranial dysplasia? |
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Definition
| When clavicles are not present or hypoplastic and there are multiple unerupted teeth |
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Term
| What are the theories of tooth eruption? |
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Definition
- Root formation
- Bone remodeling
- Dental follicle attracts osteoclasts which initiate bone remodeling
- Traction power of fibroblasts of PDL
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Term
| What are four factors controlling mesial drift? |
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Definition
- Contraction of transseptal fibers
- Adaptability of bone tissue
- Anterior compartment of occlusal force
- Pressure from soft tissue
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Term
| Differentiate between active and passive eruption? |
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Definition
| Active is to compensate for occlusal/incisal wear and passive is gradual recession of gingiva and alveolar bone; both lead to longer crown |
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Term
| Where are osteoclasts derived from? |
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Definition
| monocyte-macrophage lineage |
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Term
| Where are the minor salivary glands (generally) and are they putting out mixed, serous, or mucous secretions? |
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Definition
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Term
| Rank parotid, submandibular, and sublingual gland in terms of size and percentage of total salivary output. |
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Definition
Parotid - largest - 25% of output Submandibular - intermediate size - 60% output Sublingual - smallest - 5% |
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Term
| Which minor salivary glands are purely serous? |
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Definition
| Von Ebners located below the sulci of the circumvallate and foliate papillae |
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Term
| Where in the oral cavity are minor salivary glands not found? |
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Definition
- Anterior hard palate
- Gingiva
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Term
| Where are the Weber and Blandin-Nuhn minor salivary glands found? |
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Definition
Weber - posterior lateral tongue Glands of Blandin-Nuhn - ventral tongue |
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Term
| What gives saliva its buffering capacity? |
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Definition
| Bicarbonate and phosphate ions |
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Term
| What does the lactoferrin in saliva do? |
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Definition
| Binds free iron to deprive bacteria of it in order to enhance antimicrobial properties of saliva |
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Term
| How does saliva maintain tooth integrity? |
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Definition
| Facilitates ionic exchange of calcium and phosphate ions |
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Term
| What is the embryologic origin of the salivary glands and order of development? |
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Definition
Parotid - ectoderm Sublingual and submandibular - foregut endoderm Parotid - 4-6 weeks Submandibular 6 weeks Sublingual and minor glands 8-12 weeks Differentiate ectomesenchyme --> fibrous capsule --> septa |
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