Week 2 Flashcards
cells
the smallest structural unit of living matter, 100 trillion cells in the human body!
Cells group together to form a tissue
four basic tissues
epithelial, connective, nerve and muscle tissues
extracellular matrix
gel-like substance contains interwoven protein fibers that surrounds most cells.
*mesh like material
epithelial tissue
-Makes up outer surface of body
-Lines body cavities
Mouth, stomach and –intestines
Composed of stratified squamous epithelium
-Characterized by plentiful cells; sparse extracellular matrix.
composition of epithelial tissue
Plentiful cells closely packed, bound together
-basal lamina
basal lamina
Thin mat of extracellular matrix secreted by epithelial cells supports overlying epithelium
-Similar to the foundation of a building
-The basal lamina separates epithelial sheets from the underlying connective tissue
keratinization of epithelial cells
Epithelial cells on the surface of the skin become stronger and waterproof
-Keratinized epithelial cells
-Have no nuclei
-Form a tough, -resistant layer on skin
Palms of hands and soles of feet most heavily keratinized epithelium of the body
non-keratinized epithelial cells
Have nuclei
-Act as cushion against stress and wear of tissue
-Softer and more flexible than keratinized cells.
-Example: Lining of cheeks (buccal mucosal) permits the ability to speak, chew, and make facial expressions
blood supply to epithelial tissues
Avascular – meaning there is no blood vessels in the epithelial tissues!
Oxygen and nourishment received from blood vessels in underlying connective tissue – process is known as DIFFUSION.
connective tissue
-Fills spaces between tissues and organs in body
-Supports or binds other tissues
-Consists of sparse cells and abundant extracellular substance
-Includes cementum, dentin, alveolar bone, pulp.
connective tissue is made up of
-sparse cells
-extracellular matrix
-all dental tissue: dentin, cementum, alveolar bone, pulp
sparse cell
-Fibroblasts – fiber-builders
-Macrophages and neutrophils – phagocytes – “cell eaters” that devour dying cells and invading microorganisms.
-Lymphocytes – immune cells that play an essential role in host defense
Extracellular matrix of connective tissue
A rich, gel-like substance containing a network of strong fibers.
The fibers, rather than cells, give connective tissue its strength to withstand mechanical forces.
dental tissues of the epithelium
enamel
blood supply of connective tissue
Connective tissue has a rich blood supply that brings nourishment to both connective tissue and to the epithelial tissue that covers it
epithelial connective tissue interface
Site where epithelial and connective tissues meet in either a wavy or a smooth boundary
In most places in the body, these tissues meet in an uneven, wavy boundary
-epithelial ridges
-connective tissue papillae
epithelial ridges of connective tissue
extensions of epithelium that reach down into connective tissue.
connective tissue of papillae
fingerlike extensions of connective tissue that extend up into the epithelium
functions of wavy boundary
-Provides greater adhesion of epithelium to connective tissue by increasing surface area at the boundary where these tissues meet.
-The wavy junction increases the area from which epithelium can receive nourishment from connective tissue.
epithelial cell junctions
Cellular structures that mechanically “lock” cell to its neighbor or basal lamina
Binding cells form structurally strong unit
Gingival epithelium
A type of stratified squamous epithelium designed to function in the wet environment of the oral cavity.
-Microscopic anatomy is similar to the skin.
-Three anatomical areas
*Oral epithelium (OE)
*Sulcular epithelium (SE)
*Junctional epithelium (JE)
gingival tissue is comprised of
A thin protective layer of the epithelial tissue, that covers the underlying connective tissue.
Oral epithelium
-Covers the outer surface of the free and attached gingiva.
-Extends from the crest of the gingival margin to the mucogingival junction.
-protection
sulcular epithelium
-Lines the sulcus
-Extends from crest of gingival margin to coronal edge of junctional epithelium
- no wavy junction
-is permeable
junctional epithelium
-Located at base of the sulcus
-In health, attaches to tooth slightly coronal to cementoenamel junction (CEJ)
non keratinized
functions of JE
-JE attaches gingiva to enamel and/or the cementum of the tooth.
-Because of this attachment, the JE provides a seal at the base of the gingival sulcus or periodontal pocket.
-The JE provides a protective barrier between the plaque biofilm and the underlying connective tissue of the periodontium.
Inner basal lamina of extracellular matrix
Thin basal lamina between JE and tooth surface
external basal lamina of extracellular matrix
Thin basal lamina between JE and gingival connective tissue
functions of the gingival connective tissue
Provides solidity to the gingiva.
Attaches gingiva to cementum of the root and the alveolar bone.
Also known as lamina propria
Gingival Connective Tissue Extracellular Matrix
-Gingival connective tissue has abundant extracellular matrix.
-Cells comprise only 5% of the gingival connective tissue.
Types: fibroblasts, mast cells, macrophages, neutrophils, lymphocytes.
-Protein fibers make up 55% - 65% of gingival connective tissue.
-Fibroblasts produce connective tissue fibers
-30% to 35% gel-like material
Supragingival Fiber Bundles of the Gingival Connective Tissue
Network of rope-like collagen fiber bundles in the gingival connective tissue that are coronal to the crest of the alveolar bone.
functions of fiber bundles
-Brace free gingiva firmly against the tooth.
-Reinforce attachment of junctional epithelium to the tooth.
-Provide rigidity to withstand chewing.
-Attach gingiva to cementum, the root and bone.
-Stabilize adjacent teeth to each other
in health the PDL
Surrounds the entire tooth root and fills the space between the root and the alveolar bone
5 functions of the PDL
supportive, sensory, nutritive, formative, resorptive
supportive function
attaches the tooth to alveolar bone and suspends the tooth so it doesn’t grind on the bone during chewing
sensory function
transmits tactile pressure and pain sensations
nutritive function
- blood vessels provide nutrients to cementum and bone.
formative function
contains cementoblasts that produce the cementum throughout the life of the tooth
resorptive function
contains osteoclasts that can resorb bone and cementum.
principle fiber groups of the PDL
alveolar crest, horizontal fibers, intermediate fibers, oblique fibers, apical fibers
Alveolar crest PDL
The group of periodontal ligaments that is closest to the crown of the tooth is the alveolar crest fibers, also they run in a diagonal direction from the alveolar crest to the cervical cementum
horizontal fibers PDL
fibers run from cementum to the alveolar bone at right angles to the long axis of the tooth
Oblique fibers
run from cementum to the alveolar bone on a slant
apical fibers
run from the apex of the tooth to the alveolar bone
Interradicular fibers
run between the cementum in the furcation area of the tooth to the interradicular septum of the alveolar bone (only present in the furcation area of multi-rooted teeth)
How do PDL fibers form
-Fine collagen fibers arise from cementum and the alveolar bone proper.
-Fibers grow into the mid-portion of the periodontal ligament space.
-Fibers from cementum fuse with fibers from the alveolar bone proper.
Sharpey’s fibers
-Ends of PDL fibers that are embedded in the cementum and the alveolar bone
-Attachment of the fiber bundles occurs when cementum and bone are forming.
-As cementum forms, it hardens around the ends of Sharpey’s fibers, surrounding them with cementum.
-As alveolar bone forms, it also surrounds the opposite ends of the Sharpey’s fibers
cementum
-Calcified layer of connective tissue.
-A thin layer of cementum (blue band) covers the dentin of the root.
-Periodontal ligament (L) holds the tooth in the bony socket of the alveolar bone (B)
-Organic matrix composed of densely packed collagen fibers and proteins
-Mineralized portion made of hydroxyapatite crystals
-No blood vessels or nerves!
-Biological components include growth factor molecules
function of cementum
-Attaches periodontal ligament fibers to the root of the tooth
-Maintains integrity of the root
-Seals and covers open dentinal tubules and protects underlying dentin
-Cementum is constantly remodeling the reattachment of the periodontal ligament fibers to the root.
-Cementum grows in thickness throughout life
Compensating for attrition of the occlusal and incisal surfaces
Constantly forming at apical areas of roots to compensate for the loss of tooth tissue caused by attrition.
-Cementum is important in the periodontal reattachment or new attachment after periodontal treatment
Essential to have healthy and intact cementum surfaces after using instruments on root surfaces
types of cementum
intermediate, acellular, cellular
Acellular cementum
-Contains no living cells (no cementocytes) within the mineralized tissue as it is completely calcified
-First to be formed
-Covers cervical third or half of the root
-Not produced during the life of the tooth (formed before eruption)
Consists of mostly Sharpey’s fibers
acellular cementum
-Contains cementocytes and fibroblasts within mineralized tissue
-Found in the apical and interradicular portions of the root.
-Forms after tooth eruption
-Less calcified than acellular cementum
-Deposited at intervals throughout the life of the tooth
cementoenamel junction
Cementum may have one of three relationships with enamel:
Overlap -15% cementum overlaps the enamel
Meet - 52% cementum meets the enamel
Gap - 33% small gap between the cementum and the enamel
