periodontal macro/micro structures Flashcards
What are the periodontium components?
Gingiva
Periodontal Ligament
Cementum
Alveolar bone
What are the microstructures of the gingiva?
Gingival epithelium
Basement membrane
Gingival connective tissue
Supracrestal tissue attachment (formerly known as biologic width)
What are the macrostructures of the gingiva?
Free gingiva
Attached gingiva
Interdental gingiva
What is Free Gingiva?
The coronal demarcation of attached gingiva (AG), corresponding to the CEJ if healthy.
How commonly is Free Gingiva present in normal gingiva? (Ainamo and Loe, 1966)
1/3 of normal gingiva
What does the mucogingival junction (MGJ) represent?
The junction between keratinized gingiva and non-keratinized mucosa.
How can the mucogingival junction be determined?
1) visualization;
2) roll technique;
3) Schiller iodine solution.
What are the types of gingival epithelium?
Junctional, sulcular, and oral epithelium.
What are the layers (strata) of the oral epithelium?
Stratum corneum
stratum granulosum
stratum spinosum
stratum basale
What percentage of oral epithelium cells are keratinocytes?
90%
What is gingival epithelium?
Stratified squamous epithelium attached to the underlying connective tissue
Which layer of the oral epithelium is keratinized?
The stratum corneum.
What percentage of oral epithelium cells are non-keratinocytes?
10%
Oral epithelium is in which epithelium layers?
Stratum basale, spinosum, granulosum and corneum
What are inflammatory cells in oral epithelium?
They are the inflammatory response of oral mucosa, their location varies
Are rate pegs present or absent in Sulcular and Junctional epithelium?
Absent
Oral epithelium is what epithelium type?
Keratinized Stratified Squamous
Sulcular and Junctional epithelium are what epithelium type?
Non-keratinized Stratified Squamous
What offers defense against bacterial invasion and periodontal disease destruction?
Oral Epithelium
Sulcular and Junctional epithelium are in what epithelium layers?
Stratum basale and suprabasale
How is keratinized gingiva measured?
attached gingiva + probing depth
Are rate pegs present or absent in Oral epithelium?
Present
What is the ranking of the Intracellular Space for Sulcular, Junctional, and Oral epithelium from widest to narrowest?
- Junctional (widest)
- Suclular
- Oral (narrowest)
What is the ranking of the Permeability for Sulcular, Junctional, and Oral epithelium from greatest to least?
- Junctional (greatest)
- Suclular
- Oral (least)
What cells produce keratin in the oral epithelium?
Squamous cells, also called keratinocytes.
What is the function of keratinized oral epithelium?
It provides protection against mechanical trauma and bacterial invasion.
What is the process by which keratinocytes produce keratin and migrate to the upper layers?
Keratinization
Is the Col present in areas with missing or non-contacting teeth?
No
Where is the Col located?
Apical to the contact point, dependent on the shape and position of the contact point.
Which parts of the gingiva are keratinized?
Both the free and attached gingiva.
What is the Col in terms of gingiva?
A valley-like depression connecting the facial and lingual/palatal gingival papillae.
What type of epithelium covers the Col?
Non-keratinized epithelium.
What are the Cell Junctions for Sulcular and Oral epithelium?
Desmosomes
Hemidesmosomes (for anchorage to basement membrane)
Why is the Col important?
It is considered an important site for the initiation of periodontal inflammation.
What is the basement membrane in gingival epithelium?
The interface between the basal epithelial cells and the underlying connective tissue (lamina propria).
What are the Cell Junctions for Junctional epithelium?
Desmosomes
Hemidesmosomes (anchorage to the tooth and basement membrane)
T or F: Intercellular space differs among the types of gingival epithelium
True
What is the role of desmosomes in gingival epithelium?
connect epithelial cells and are characterized by anchoring fibrils.
What is associated with autoantibodies directed against antigens of desmoglein, which helps to form desmosomal junctions between cells?
PEMPHIGUS Vulgaris
What are the two layers of the basement membrane?
Lamina lucida (electron lucent) and lamina densa (electron dense).
How is lamina lucida connected to the stratum basale?
hemidesmosomes
What is the composition of collagen fibers in lamina propria?
Type I collagen (major)
Type III collagen and elastin fiber (minor)
How is lamina densa attached to the connective tissue?
anchoring fibrils
What is the disease associated with autoantibodies directed against antigens in the basal membrane zone?
Mucous Membrane PEMPHIGOID
What is the lamina propria?
The connective tissue located below the basement membrane.
What are the main components of the Lamina Propria
Collagen fibers
Cells
Ground Substance
What are the two layers of the lamina propria?
Papillary layer and reticular layer
What does the reticular layer consist of?
dense irregular connective tissue with thick fibers
What does the papillary layer consist of and located?
loose connective tissue
directly below the basement membrane.
What is the function of cells in lamina propria?
Fibroblast produce connective tissue fibers:
1.Collagen fibers
What is the composition of cells in lamina propria?
Fibroblast (65%)
Mast cells, macrophages and inflammatory cells
What is the function of collagen fibers in lamina propria?
Tensile strength
What is the composition of ground substance in lamina propria?
Clear, viscous fluid that fills the space between the cells and fibers.
Composed of glycosaminoglycans and proteoglycans
What is the function of ground substance in lamina propria?
Glue for the cells to attach to the matrix
Molecular sieve for substances to travel between blood capillaries and cells.
What is the composition of the Extracellular Matrix (ECM)
Glycosaminoglycans (GAGs)
proteoglycans
collagenous
non-collagenous proteins
How do GAGs participate in biological processes?
They regulate their protein partners called proteoglycans.
What is the function of the composition of the ECM
Scaffold to support and anchor cells, mediates adhesion, cell signaling and transport of nutrients
What are the structural proteins in the ECM?
Collagen and elastin.
What are the adhesive glycoproteins in the ECM?
Fibronectin and laminin.
What are the types of glycosaminoglycans (GAGs)?
Hyaluronan, chondroitin sulfate, dermatan sulfate, heparan sulfate, heparin, and keratan sulfate.
What are proteoglycans?
Proteins that are heavily glycosylated.
Where is Dermatan sulfate located and involved in?
blood vessels
involved in wound repair
What are proteoglycans in the ECM?
Aggrecan and decorin.
What are Glycosaminoglycans (GAGs)?
Linear polymers containing repeating disaccharides of N-acetyl hexosamine and a hexuronic acid or hexose.
Where is Heparan sulfate located?
Basement membranes and cell surfaces
Where is Hyaluronic acid located?
ECM of loose connective tissue
Collagen Type III Tissue Distribution
Gingiva
Where is Chondroitin-4 sulfate and Keratan sulfate located?
Bone
Collagen Type I Tissue Distribution
bone, gingiva, ligament
Collagen Type V Site of Synthesis
Smooth muscle
What is the basic unit of a proteoglycan?
A core protein covalently attached to glycosaminoglycans (GAGs).
Collagen Type I Site of Synthesis
Fibroblasts
Osteoblasts
Odontoblasts
What is Connective Tissue Growth Factor (CTGF)?
An ECM protein involved in the control of biological processes.
Collagen Type V Tissue Distribution
bone, gingiva
Collagen Type III Site of Synthesis
Fibroblasts
What happens when Connective Tissue Growth Factor is upregulated?
It is linked to multiple chronic diseases, such as liver fibrosis and congestive heart failure.
What is Transforming Growth Factor beta (TGF-β)?
A cytokine belonging to the transforming growth factor superfamily.
What are cytokines known for?
proteins that act as immunomodulating agents.
Which cells produce cytokines?
white blood cell lineages, including neutrophils, lymphocytes, natural killer cells, and monocytes.
What is the triple-helical structure of collagen made of?
glycine, proline, and hydroxyproline.
What is the characteristic repeating motif in collagen?
Gly-Pro-X, where X can be any amino acid.
What does collagen provide to body tissues?
Collagen provides strength and structure to body tissues.
What contributes to the strength of collagen?
The fiber organization within the ECM contributes to its strength.
What condition is caused by a deficiency in Vitamin C?
Scurvy
What is required for the hydroxylation of proline?
Vitamin C.
What happens if proline hydroxylation fails?
It leads to the formation of defective pro-α collagen chains that fail to form a stable triple helix and are degraded within the cell.
Is collagen resistant to degradation?
Yes
What are the consequences of defective collagen formation?
Blood vessel fragility and loss of tooth attachment within sockets.
What happens during stimulation of collagen?
Collagen Fragments Stimulate the Production of New Collagen
What enzymes digest collagen?
Matrix Metalloproteinases (MMP)
What are MMPs regulated by?
Tissue Inhibitors of MMPs (TIMPS)
What is the MMP of Collagenase 2?
MMP-8
What are the Substrates of Collagenase 2?
Collagens I, II, III
What term did Gargiulo describe in 1961?
The “Physiologic dentogingival unit.”
Who introduced the term “biologic width” and when?
Cohen in 1962.
What does biologic width refer to?
The space over the tooth surface occupied by connective tissue (CT) and epithelial attachments.
What term replaced “biologic width” in 2017?
“Supracrestal tissue attachment” (STA), as defined by Jepsen et al. in 2018.
What are the phases of bone remodeling?
Resting
Resorption (osteoclasts digest old bone)
Reversal (mononuclear cells on the bone surface)
Formation (osteoblasts lay down new bone)
Mineralization (osteocytes).
How does chronic inflammation contribute to alveolar bone loss in periodontitis?
By uncoupling bone formation from resorption.
What local factors regulate bone remodeling?
Insulin-like growth factors (IGFs)
Prostaglandins
Tumor growth factor-beta (TGF-beta)
Bone morphogenetic proteins (BMP)
Cytokines
RANK/receptor/OPG system
What is the spatial consideration in inflammation-induced bone loss?
Bacteria migrate inside connective tissue and release bone-resorbing mediators that induce osteoclastogenesis and bone loss.
What is the temporal consideration in inflammation-induced bone loss?
Increased inflammatory mediators prolong the resorption phase of bone remodeling.
