ICP-24 Periodontal tissues in health and disease Flashcards
(115 cards)
1
Q
What is the periodontium
A
Collective term describing tooth supporting tissues including the root cementum, periodontal ligament, alveolar bone and gingiva
2
Q
What and when is the first sign of tooth development
A
Around the 6th week - thickening of the oral epithelium
3
Q
What is the tooth germ
A
This is an aggregation of cells derived from the ectoderm of the first pharyngeal arch and the ectomesenchyme of the neural crest - it is organised into 3 parts
4
Q
What is the tooth germ comprised of
A
Enamel organ: enamel and primary epithelial attachment
Dental papilla: Pulp and dentin
Dental follicle: cementum, periodontal ligament, alveolar bone
5
Q
What is the gingiva and its general functions
A
- The part of the oral mucosa covering the tooth-bearing part of the alveolar bone and the cervical neck of the tooth
- Major peripheral defence against microbial infections and mechanical trauma
- Sensory function and it is well innervated with pain, touch and temp receptors
6
Q
What are the macroscopic borders of the gingiva
A
- Gingival margin at the point where the crown and gingiva meet
- Gingival groove - slightly above gingival margin, not sure what defines this (shallow linear depression)
- Muco-gingival junction - between oral mucosa and attached gingiva
7
Q
What are the different parts of the gingiva
A
- Interdental gingiva between teeth
- Free gingiva between the gingival margin and gingival groove
- Attached gingiva between the gingival groove and muco-gingival junction
8
Q
What is the attached gingiva and describe some of its properties
A
- Demarcated by gingival groove and mucogingival junction
- Firm, resilient and tightly bound to the underlying periosteum of the alveolar bone
- Covered by keratinised epithelium
- Width is greatest over buccal surface of maxillary incisors and narrows over buccal surface of mandibular premolars
9
Q
What is the free gingiva and describe some of its properties
A
- Delicately attached to the tooth surface
- Cover about 1-1.5mm of tooth surface
- Surrounds the cervical part of the teeth and is separated from the teeth by a fine space called gingival sulcus
10
Q
What is the gingival sulcus and describe some of its properties
A
- Shallow crevice/space around teeth bounded by the tooth on one side and the sulcular epithelium on he other side
- The coronal extent of the gingival sulcus is in the gingival margin
- It is V shaped
11
Q
What is the gingival zenit
A
The most apical point of the marginal gingival scallop is called the gingival zenith
12
Q
What is the interdental gingiva and describe some of its properties
A
- Occupies the gingival embrasure, which is the inter proximal space beneath the area of tooth contact
- Can be pyramidal or have a col shape
- Col is a valley like depression that connects a facial and lingual papilla
- The shape of the interdental gingiva depends on the contact point between the 2 adjacent teeth
13
Q
What types of periodontal phenotype are there
A
Thin scalloped
Thick scalloped
Flat thick
14
Q
Describe a thin scalloped periodontal phenotype
A
High association with slender triangular shaped crown
Subtle cervical convexity
Interproximal contacts close to the incisal edge and a narrow zone of KT, clear thin delicate gingiva and a relatively thin alveolar bone
15
Q
Describe a thick scalloped periodontal phenotype
A
Clear thick fibrotic gingiva, slender teeth, narrow zone of KT and a high gingival scallop
16
Q
Describe a flat thick periodontal phenotype
A
More square shaped tooth crowns, pronounced cervical convexity, large inter proximal contact located more apically, a broad zone of KT, clear thick, fibrotic gingiva and a comparatively thick alveolar bone
17
Q
What is the oral gingival epithelium
A
Extends from the mucogingival junction to the tip of the gingival crest and is subdivided into the free marginal gingiva and the attached gingiva
18
Q
What is the oral gingival epithelium made up of
A
Keratinised, stratified squamous epithelium, 0.2-0.3 mm in thickness, originated from the oral mucosa made up of:
- Stratum corneal
- Stratum granulosum
- Stratum spinosum
- Stratum basal
19
Q
What cell types can you find in the oral gingival epithelium
A
- Principal cell type: keratinocytes
- Langerhans cells
- Melanocytes
- Merkel’s cells
- Inflammatory cells
20
Q
What is the oral sulcular epithelium
A
Lines the gingival sulcus and extends from the tip of the gingival crest to the the most coronal portion of the junctional epithelium
21
Q
What kind of epithelium is the oral sulcular epithelium made of and name some of its properties
A
- Non-keratinised, stratified squamous epithelium
- No rete pegs
- Acts as a semipermeable membrane
- Originates from the oral mucosa
- Cell layers similar to the oral gingival epithelium
- Forms gingival sulcus/crevice
22
Q
What is the histological and clinical depth of the oral sulcular epithelium
A
Histological - 0-0.5mm
Clinical - 0.5-3mm
23
Q
What is the junctional epithelium
A
Forms the attachment of the gingiva to the tooth structure
24
Q
What are the properties and epithelium type of the junctional epithelium
A
- Non-keratinised, stratified squamous epithelium
- Wider space between cells
- No rete pegs
- High turnover rate
- Provides attachment to tooth surface via hemidesmosomes
- Provides a vehicle for the bidirectional movement of substances between gingival connective tissue and oral cavity
- Provides an epithelial barrier against plaque bacteria
- Originates from the enamel organ
25
What is the dentogingival unit
The JE and the gingival fibres are considered a functional unit referred to as the dentogingival unit
26
What do the gingival fibres do
The attachment of the JE to the tooth is reinforced by the gingival fibres that brace the marginal gingiva against the tooth surface
27
What is the CT of the gingiva known as
The lamina propria
28
What are the properties of the lamina propria of the gingiva
- Highly vascularised
- Protects the root surface and alveolar bone from external oral environment
- Provides support to the epithelial tissues
- Made up of the papillary and reticular layer
29
What are the layers of the Lamina propria of the gingiva
- Papillary layer - papillary projections between the epithelial rete pegs
- Reticular layer - contiguous with the periosteum
30
What do the fibroblasts do in the lamina propria
- Synthesise collagen and elastic fibres as well as glycoproteins and GAGs of the amorphous intercellular substance
- Regulate collagen degradation
31
Besides fibroblasts what other cells can be found in the lamina propria
Immune cells: mast cells, plasma cells, lymphocytes and neutrophils
32
What can be found in the matrix of the lamina propria
- Ground amorphous substance: fills the space between cells and fibres
- Fibres: collagen type 1 and non collagen fibres
33
What fibres can you find in the lamina propria of the gingiva
Collagen type 1
Reticulin
Oxytalan
Elastic
34
What are the principal groups of fibres in the matrix of the lamina propria
- Dentogingival
- Alveologingival
- Dentoperiosteal
- Circular
- Trans-septal
35
Describe the dentogingival fibres of the lamina propria
- Project from the cementum in a fan like configuration out into the free gingival tissue of facial, lingual and inter-proximal surfaces
- Provide gingival support
36
Describe the alveolo-gingival fibres of the lamina propria
- Start from the periosteum covering the alveolar crest
- Project coronally into the attached gingiva
- They attach gingiva to bone
37
Describe the dento-periosteal fibres of the lamina propria
- Embedded in the same portion of the cementum as the dentogingival fibres
- But run their course apically over the vestibular and lingual bone crest
- Terminate in the attached gingiva
- Anchor tooth to bone and protect PDL
38
Describe the circular fibres of the lamina propria
- Run in the marginal and interdental gingiva
- Encircle each tooth in a cuff- or ring- like fashion
- Maintain contour and position of free marginal gingiva
39
Describe the trans-septal fibres of the lamina propria
- Extend between the supra-alveolar cementum of adjacent teeth
- Run straight across the interdental septum and are embedded in the cementum of adjacent teeth
- Support interdental gingiva, secure positions of adjacent teeth and protect inter-proximal bone
40
What is the Gingival Crevicular Fluid
- Serum transudate or inflammatory exudate that can be found in the crevice
- Arises from the gingival plexus of blood vessels in the gingival corium, subjacent to the epithelium lining the dentogingival space
- Mix of molecules originating from blood, host tissues and sub gingival plaque.
41
What cells can be found in the gingival crevicular fluid and where they originate from
Epithelial cells - oral sulcular and JE shows high turnover rate
Bacteria - from plaque
Leukocytes - from gingival plexus of blood vessels - immune response
Erythrocytes - from damage to small blood vessels
42
Describe the general properties and location of the cementum
- Avascular mineralised tissue covering the root surface
- begins at cervical portion of the tooth at the CEJ and continues to the apex
- less hard than dentin
- very permeable
43
What are the main functions of the cementum
- Anchorage = medium for attachment to the collagen fibres of the PDL
- Repair/resorption = continuous deposition thus it repairs the damages
- protection (fluoride) = seal for open dentinal tubules
44
What cell types can be found in cementum
- Cementoblasts
- Cementocytes
- Cementoclasts
45
What are cementoblasts and what do they do
- Mesenchymal cells that synthesise collagen and protein polysaccharides, which make up the organic matrix of cementum
- they line the root surface
46
What are cementoblasts and what do they do
- Spider shaped cells
- During the formation of cellular cementum, cementoblasts become entrapped within their own matrix and become cementocytes
47
What are cementoclasts and what do they do
- multinucleated giant cells
| - resorption and repair function
48
What are the anorganic matrix components of cementum
- Calcium and phosphate (hydroxyapatite)
- trace elements (copper, fluorine, iron, potassium, sodium)
- Highest fluoride content
49
What are the organic matrix components of cementum
- Type I and III collagen embedded in an inter fibrillar ground substance consisting of glycoproteins
- Non collagenous proteins (alkaline phosphatase, bone sialoprotein, fibronectin, osteocalcin)
50
What is the extrinsic fibre system made up of
- Consists of principal fibres (Sharpey's fibres) that are continuous with the principal fibres of the periodontal ligament
51
Where do the "extrinsic" fibres originate and how are they orientated
Originate from PDL fibroblasts and are considered "extrinsic" to the cementum.
These fibres are orientated more or less perpendicularly to the cementum surface
52
What do the extrinsic fibres of the cementum do
They play a major role in tooth anchorage
53
Where does the intrinsic fibre system originate from and how are they orientated
Fibres produced by cementoblasts and are orientated more or less parallel to the cementum surface
54
What are the properties and functions of the intrinsic fibres of the cementum
- The fibres are dense and irregularly arranged within the cementum matrix
- Mainly located at sites undergoing repair, following surface resorption
- No role in tooth anchorage
55
What are the 4 main types of cementum
- Acellular Afibrillar Cementum
- Acellular Extrinsic Fibre Cementum
- Cellular Intrinsic Fibre Cementum
- Cellular Mixed Stratified Cementum
56
What are the properties and functions of Acellular Fibrillar Cementum
- May be found as coronal cementum over enamel at CEJ
- Contains neither cells nor extrinsic or intrinsic collagen fibres
- Unknown function
57
What are the properties and functions of Acellular Extrinsic Fibre Cementum
- Coronal 2/3 of the root
- Comprised of collagen fibres and GAGs
- Product of cementoblasts and fibroblasts
- Densely packed bundles of Sharpey's fibres in a non-cellular ground substance
- Major function in toot anchorage
58
What are the properties and functions of Cellular Intrinsic Fibre Cementum
- Usually present as a component of cellular mixed stratified cementum
- Mainly found at furcations and apical root
- Cells but no collagen fibres
- Participates in the repair process of resorbed roots
59
What are the properties and functions of Cellular Mixed Stratified Cementum
- Apical third of the root and furcation area
- Extrinsic (sharpey's) and intrinsic fibres and irregularly distributed cells
- Presence of lacunae with canaliculi in which reside cementocytes
60
What are the effects of ageing on cementum
- Cementum surface becomes more irregular due to calcification of some fibre bundles where they were attached to cementum
- Cemental width may increase (5-10x)
- Increase in width is greater apically and lingually
- Continuous increase of cementum in apical zone may result in obstruction of apical foramen
61
What is the periodontal ligament and where is it found
- Soft specialised CT between the cementum and bone socket wall
- Extends coronally up to the most apical part of the CT of the gingiva
62
What are the main functions of the periodontal ligament
- Supportive
- Sensory/proprioception
- Formative
- Protective
- Regeneration/wound healing
- Nutritive
63
What cells can be found in the periodontal ligament
- Fibroblasts
- Cementoblasts
- Osteoblasts
- Osteoclasts
- Odontoclasts
- Epithelial cells
- Nerve cells
- Immune cells
64
Describe the distribution and function of fibroblasts in the periodontal ligament
- Predominant cell in PDL
- Regularly distributed throughout the ligament and are oriented with their long axis parallel to the direction of collagen fibrils
- Synthesise and shape the proteins of the ECM, in which collagen fibrils form bundles that insert into cementum and bone as Sharpey's fibres
65
What are the epithelial cell rests of Malassez
- They are discrete clusters of residual cells from Hertwig's epithelial root sheath (HERS) that did not completely disappear
66
What are the functions of epithelial cell rests of malassez
To maintain PDL homeostasis to prevent ankylosis and maintain PDL space, to precent root resorption, to serve as a target during PDL innervation and to contribute to cementum repair
67
What fibres can be found in the ECM of the PDL
- Collagen
- Elastic
- Reticular
- Oxytalan
- Indifferent fibre plexus
68
What is the ground substance of the PDL made up of
Proteoglycans and Glycoproteins
69
How do collagen fibres run in the PDL
- Originate as fibres of different diameters and are embedded into the cementum on one side of the periodontal space and into the alveolar bone on the other side (sharpey's fibres)
70
What happens once sharpey's fibres are embedded into the wall of the alveolar tooth
These fibres calcify to a certain degree and are associated with an abundance of non-collagenous proteins (osteopontin and bone sialoprotein)
71
What are the 5 types of principal fibres
- Alveolar crest fibres
- Horizontal fibres
- Oblique fibres (most abundant)
- Apical fibres
- Inter-radicular fibres
72
Describe the orientation and functions of the alveolar crest fibres of the PDL
- Extend obliquely from cementum just beneath the CEJ to alveolar crest
- Resist tilting, intrusive, extrusive and rotational forces
73
Describe the orientation and functions of the horizontal fibres of the PDL
- Attach to the cementum apical to the alveolar crest fibres and run perpendicularly from the root of the tooth to the alveolar bone
- Pass from their cementum attachment directly across the PDL space to become inserted in alveolar process as Sharpey's fibres
- Resist horizontal and tipping forces
74
Describe the orientation and functions of the Oblique fibres of the PDL
- Run from cementum in an oblique direction to insert into bone coronally
- Most abundant (2/3 of ligament)
- Resist vertical and intrusive forces
75
Describe the orientation and functions of the apical fibres of the PDL
- Radiate from cementum around the apex of the root to the bone, forming base of the socket or alveolus
- Resists force of luxation, prevent tooth tipping and protect blood and lymph vessels and nerves transversing PDL space at root apex
- Not seen in incompletely formed roots
76
Describe the orientation and functions of the Inter-radicular fibres of the PDL
- Only found between the roots of multirooted teeth. Extends from radicular cementum to inter-radicular alveolar bone
- Resist tooth tipping, torquing and luxation
77
What is the Alveolar bone
Specialised bone structure that contains the sockets of the teeth and supports the teeth - develop from the dental follicle
78
What does the alveolar bone consist of
- Alveolar process/supporting alveolar bone (maxilla and mandible)
- Alveolar bone proper (bundle bone and Sharpey's fibres)
79
What are the main functions of the alveolar bone
- Anchorage
- Protection and support for teeth
- Bone synthesis
- Absorbs and distributes forces
80
What is the alveolar process
Alveolar process is continuous with basal bone of maxilla and mandible
81
Describe the cortical bone of the alveolar bone
- Similar to cortical bone anywhere else in body
- Extends on the lingual/palatal and buccal side
- thicker in mandible vs maxilla
82
Describe the cancellous bone of the alveolar process
- Similar to cancellous bone anywhere in body
- Honeycomb structure
- Network of thin highly connected trabecular containing bone marrow
83
What is the alveolar bone proper
- Continuation of the cortical plate, lines the tooth socket
- Surrounds the root of the teeth and gives attachment to the principal fibres of PDL
- Specialised type of compact bone composed of bundle bone and Haversian bone
84
Why is alveolar bone proper also called bundle bone
- Numerous bundles of Sharpey's fibres pass into it from the PDL
85
What cell types can be found in the alveolar bone
- Osteoblasts
- Osteocytes
- Bone lining cells
- Osteoclasts
86
What are the organic components of the bone matrix of the alveolar bone
- Collagen (type I mainly)
| - Non-collagenous proteins: Proteoglycans, glycosylated proteins
87
What are the inorganic components of the bone matrix of the alveolar bone
- Hydroxyapatite crystals
| - Impurities (carbonate, magnesium, acid phosphate)
88
What else besides organic and inorganic components is in the bone matrix
Water
89
Why does the alveolar bone proper appear more radiopaque than mature lamellar bone
Contains less mature and fewer intrinsic collagen fibrils in the intercellular substance, but has more calcium salts
90
What is periodontal disease
A chronic multifactorial inflammatory disease initiated by bacterial microorganisms and characterised by a severe chronic inflammation that leads to progressive destruction of the tooth supporting apparatus, tooth loss and eventually masticatory dysfunction
91
What is mainly responsible for periodontal tissue damage
the inflammatory immune response
92
What is plaque induced gingivitis
Inflammation of the gums due to plaque accumulation
93
What are the clinical characteristics of plaque-induced gingivitis
- Erythema
- Edema
- Tenderness
- Enlargement
- Swelling
- Redness
- Bleeding on probing
- No bone loss
- REVERSIBLE
94
What is periodontitis
Supra and sub gingival plaque/calculus accumulation
95
What are the clinical characteristics of periodontitis
- Erythema
- Edema
- Tenderness
- Enlargement
- swelling
- redness
- tooth mobility
- gum recession
- halitosis
- Pocket formation
- bleeding on probing
- Loss of periodontal attachment
- IRREVERSIBLE
96
What is a gingival pocket
Formed by gingival enlargement without destruction of the underlying tissues. The sulcus deepens because of the increased bulk of the gingiva
97
What is a periodontal pockets
Occurs with destruction of supporting periodontal tissues and can be:
- Supra bony (supracrestal)
- Intrabony
98
What is a supra bony periodontal pocket
Horizontal bone loss and pocket base coronal to the crest of the alveolar bone
99
What is an intrabony periodontal pocket
Vertical bone loss and pocket base below the crest of the alveolar bone
100
What are the 4 stages of a progressing gingival/peridontal lesion/inflammation ting
1. Initial lesion
2. Early lesion
3. Established lesion
4. Advanced lesion
101
What are the histopathological features of an initial lesion
- Corresponds to the clinically healthy gingival tissue
- Slightly elevated vascular permeability and vasodilation
- Increased GCF flows out from the sulcus
- Migration of leukocytes, primarily neutrophils through the gingival CT, the JE and the sulcus
102
What are the histopathological features of an early lesion
- Corresponds to early gingivitis that is clinically evident
- Increased vascular permeability, vasodilation and GCF flow
- Large numbers of infiltrating leukocytes
- Degeneration of fibroblasts
- Collagen destruction resulting in collagen depleted areas of the CT
- Proliferation of the JE and sulcular epithelium into collagen depleted areas
103
What are the histopathological features of an established lesion
- Corresponds to established chronic gingivitis
- Dense inflammatory infiltrate
- Elevated release of MMPs and lysosomal contents from neutrophils
- Significant collagen depletion and proliferation of epithelium
- JE is no longer closely attached to the tooth surface and the pocket epithelium has formed which contains a lot of neutrophils
104
What are the histopathological features of an advanced lesion
- Marks the transition from gingivitis to periodontitis
- Pocket deepens, thus anaerobic ecological niche forms
- Predominance of neutrophils in the pocket epithelium and in the pocket
- Dense inflammatory infiltrate in the CT
- Apical migration of JE to preserve intact epithelial barrier
- Continued collagen breakdown resulting in large areas of collagen depleted CT
- Osteoclastic resorption of alveolar bone
105
What are the key types of mediators that orchestrate the host response
Cytokines
Prostaglandins
Matrix Metalloproteinases (MMPs)
106
What are cytokines
Soluble proteins secreted by cells that act as messenger molecules that transmit signals from one cell to another.
Effective in very low cones and primarily act locally
107
What are the functions of cytokines
- Initiation and maintenance of immune and inflammatory responses
- Regulation of growth and differentiation of cells
108
What are some examples of cells that release cytokines
```
Neutrophils
Macrophages
Lymphocytes
Fibroblasts
Epithelial cells
```
109
What are prostaglandins and how are they produced
- Group of lipid compounds derived from arachidonic acid
| - Arachidonic acid is metabolised by cycloxygnease-1 and 2 to generate PGs, thromboxjnes and prostacyclins
110
What are the functions of prostaglandins
- Important mediators of inflammation, particularly PGE2
| - Produced mainly by macrophages and fibroblasts, but also other cells
111
What are the roles of PGE2
- Is a potent vasodilator
- Induce cytokine production by various cells
- Acts on fibroblasts and osteoclasts to induce production of MMPs = tissue turnover/tissue destruction in gingivitis and periodontitis
112
What can cause the increased production of PGE2 in inflamed tissues
Upregulation of COX-2 by IL-1b, TNFalpha and bacterial LPS
113
What are MMPs
Family of proteolytic enzymes responsible for remodelling and degradation of the matrix components
114
What are the functions of the MMPs
- Degrade basement membrane and extracellular matrix components
- Also have regulatory properties, modulating enzymes, chemokine, cytokines and release bioactive molecules
115
What kinds of cells produce MMPs
```
Neutrophils
Macrophages
Fibroblasts
Epithelial cells
Osteoblasts
Osteoclasts
```
