Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

CSP3 YR5- Restorative > Anatomy and Histology of the Periodontium COPY > Flashcards

Anatomy and Histology of the Periodontium COPY Flashcards

1
Q

What is the periodontum made up of?

A

Cementum
PDL
Alveolar bone
Gingiva

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the cementum?

A

Thin layer of calcified tissue covering radicular dentine
Cervically, it is 10-15µm in thickness
Apically, it is 50-200µm thick
Could exceed 600µm at root apex
Adheres to dentine and to the periodontal ligament

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the characteristics of the cementum?

A

Capable of repair and regeneration.
Formed throughout life, allowing reattachment of the periodontal ligament.
Similar to bone in composition, but not innervated and avascular.
Cementum is pale yellow and has a dull surface.
Easily abraded cervically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the classification of the cementum?

A

Cellular and Acellular
Cellular cementum contains cementocytes.
Acellular cementum covers the dentine.
Cellular cementum mainly in the apical area and inter-radicular areas overlying acellular cementum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How do the PDL and the cementum interact?

A

Fibres in the periodontal ligament run into the organic matrix of the precementum
Mineralisation of the precementum leads to the incorporation of these fibres
They are known as Sharpey’s fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the PDL?

A

Dense fibrous connective tissue that occupies the space between the root and the alveolar bone
Continuous with the gingival connective tissue and the pulp
Variation in width; location, function and age
Narrower in permanent teeth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the functions of the PDL?

A

Provision of the tissue attachment between the tooth and alveolar bone. Thus is responsible of tooth support and protection
Responsibility for the mechanism by which the tooth attains and maintains its functional position
Maintenance and repair of cementum and alveolar bone Neurological control of mastication by its mechanoreceptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the composition of the PDL?

A

Fibres: collagen, oxytalan
Ground substance
Cells: fibroblasts, cementoblasts,osteoblasts, osteoclasts, cementoclasts, epithelial cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What type of collagen is present in the PDL?

A

70% type I, 20% type III.
Small amounts of types V and VI
Traces of IV and VII with the rests of malassez and blood vessels
Type XII collagen: non fibrous, linked to other collagens and may be involved in the periodontal ligament architecture regulation
Much of the collagen is gathered into bundles (the principal fibres) 5μm in diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the fibres called in the PDL

A

Principal fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Name the 5 different orientation of the principle fibres?

A
  1. Dentoalveolar crest fibres 2. Horizontal fibres.

3. Oblique fibres 4. Apical fibres 5. Interradicular fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the zone of shear?

A

Site of remodelling during eruption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the Sharpey’s fibres?

A

The collagen fibres inserted into cementum and bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is Oxytalan?

A

Oxytalan fibrils are unbanded arranged parallel to the long axis of the fibre
Immature elastin fibres (pre-elastin)
3% of fibre composition
Attached to cementum and leave to the ligament in different directions
Rarely incorporated in bone
Different course according to region
Terminate around blood vessels and nerves
Fibres are 0.5μm-2.5μm in diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the composition of ground substance?

A

Mainly secreted by fibroblasts: Hyaluronate glycosaminoglycans
Proteoglycans: Proteodermatan sulphate
PG1 (contains hybrids of chondroitin sulphate and dermatan sulphate)
Glycoproteins
Fibronectin
Tenascin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Name the cells of the PDL?

A
  1. Fibroblasts 2. Cementoblasts. 3. Osteoblasts 4. Osteoclasts and cementoclasts.5. Epithelial cells 6. Immune cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are fibroblasts and their functions?

A

Responsible for the regeneration of the periodontal ligament
Role in adaptive responses to mechanical loading
Shape variations
Many cytoplasmic processes
Low nuclear/cytoplasmic ratio
Prominent nucleoli
Protein synthesizing organelles
Collagen degradation (fibroblasts are also fibroclastic)
Intracellular collagen profiles
Secretion of matrix metalloproteinases and tissue inhibitors to metalloproteinases
Collagenase production is regulated by exposure of cytokines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are cementoblasts?

A

They line the surface of the cementum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are osteoblasts and their functions?

A 
They line the tooth socket.
Resemble cementoblasts.
Prominent when there is active bone formation.
Basophilic cytoplasm, cuboidal cells.
Prominent basal round nucleus, protein synthesizing organelles.
Inactive osteoblasts are flat.
Desmosomes and tight junctions.
Fine cytoplasmic processes.
20
Q

What are osteoclasts and their function?

A 
Cementoclasts = odontoclasts
They arise from blood macrophages
Howship’s lacunae in bone.
Small mononuclear to giant multinuclear
Brush border: striated part of the cell that is adjacent to bone, they represent microvilli
Many vesicles with acid phosphatase
21
Q

How are epithelial cells involved in the periodontium?

A

Epithelial cell rests of Malassez
Closely packed cuboidal cells
Basal lamina
Cyst formation when stimulated

22
Q

How is the PDL supplied with blood?

A 
Superior and inferior alveolar arteries
Arteries perforating the alveolar bone
Arteries entering the pulp
Major vessels between principal fibres
Capillary plexus around teeth
Fenestrations
Veins do not accompany the arteries
Intra-alveolar venous networks, prominent around the apex of the alveolus
23
Q

How is the PDL supplied with nerve supply?

A

Sensory nerve fibres: nociception and mechanoreception
Autonomic nerve fibres: blood vessels
Nerve fibres enter via the apical region of the ligament, while others enter through the alveolar wall

24
Q

What is the alveolar bone and its function?

A

The part of the jaw that supports and protects the teeth

25
What is the composition of bone?
Bone is composed of 60% inorganic component, 25% organic component and 15% water by weight. Inorganic composition: Calcium hydroxyapatite Ca10(PO4)6(OH)2. Mainly carbonated hydroxyapatite in the form of needle-like crystallites or thin plates. Organic composition: Collagen (mainly type I) forms 90% of the extracellular matrix. There are also serum proteins, acidic glycoproteins and small proteoglycans
26
Describe the organic matrix of the bone?
Over 90% of the organic matrix is made of collagen fibrils, mainly collagen type I Proteoglycans such as chondroitin sulphate and heparan sulphate glycosaminoglycans mainly in the form of decorin and biglycan. Proteoglycans may regulate collagen fibril diameters and may have a role in mineralisation. Glycoproteins such as osteonectin, osteopontin, thrombospondin, osteocalcin and fibronectin are also present. Osteonectin can bind to calcium and thus is thought to be involved in mineralisation. Osteocalcin is only synthesised by osteoblasts and odontoblasts. Exogenous proteins that circulate the blood and become locked in bone such as cytokines and growth factors have an important role in the life cycle of bone cells. Bone morphogenetic proteins (BMP)s are present in bone. There are 8 proteins in this family (BMP-1 to BMP-8). They are part of the transforming growth factor beta (TGF-β) family (apart from BMP-1). BMP(s) induce bone formation by influencing the movement, cell division, and differentiation of stem and osteoprogenitor cells.
27
What are the different types of bone cells and their functions?
Osteoblasts secrete the organic extracellular matrix of new bone Osteoid which rapidly undergoes mineralisation to form bone. Osteoblasts become trapped in bone in lacunae osteocytes. Osteoclasts are multinuclear cells involved in bone remodelling. Bone lining cells: flat cells line bone during periods of inactivity. Osteoprogenitor cells: Stem cells beneath the osteoblast layer.
28
What are the 2 main forms of bone and their structure?
Woven bone is immature bone, with random organisation of its collagen. Lamellar bone is composed of successive layers (lamellae). It may be formed as a solid mass (compact bone), or in an open sponge-like manner (cancellous bone)
29
What is the composition/structure of compact bone?
Compact bone is made of parallel bone columns which are disposed parallel to the long axis of long bones (in line of stress exerted on the bone) Columns are made of concentric bony layers (lamellae) arranged around a central channel with blood vessels, lymphatics and nerves (Haversian canals) Haversian canals with their lamella form the haversian systems (osteon). Neurovascular bundles interact with each other via Volkmann’s canals that pierce the columns at right angle or obliquely to haversian canals. Osteocytes in their lacunae interact with each other and with the central canal via cytoplasmic extensions in canals called canaliculi. The outermost layer of compact bone gives way to dense cortical bone Because of its position, compact bone acts as weight bearing pillars. Compact bone is able to withstand high levels of mechanical stress. The innermost aspect of compact bone, the lamellae merge with trabeculae of cancellous (spongy bone)
30
What is the composition/structure of the spongy bone?
Cancellous (spongy) bone is made of a network of bone trabeculae separated by interconnected spaces containing bone marrow. Trabeculae are thin and composed of irregular bone lamellae No haversian canals are present in cancellous bone and osteocytes get their nutrition via canaliculi connecting them to blood sinusoids in the marrow Spongy bone gives bone its flexibility due to the presence of marrow spaces Trabeculae are aligned along lines of stress so as to withstand forces applied to the bone while adding minimally to the mass
31
What is the name of the landmark which shows bone resorption?
Bone resorption: Howship’s lacunae. | Longer snail track resorption lacunae
32
What is resting bone?
projections marking the sites of extrinsic mineralised Sharpey’s fibres Separated by areas with intrinsic mineralised collagen
33
What is the structure of the alveolar bone?
Outer and inner parallel alveolar plates Sockets are separated by interdental septa Roots are separated by interradicular septa Fundus: socket floor Cribriform plate, bundle bone In radiographs, thin white line, the lamina dura Cribriform plate 0.1- 0.5mm in thickness External alveolar plates 1.5-3mm in thickness Variable around anterior teeth
34
When does bone remodelling occur?
During childhood, bone deposition exceeds resorption
35
How does bone remodelling occur?
Bone resorption factors affect mainly osteoblasts: Osteoblasts could stimulate the production of osteoclasts by their release of cytokines and growth factors. Osteoblasts could produce enzymes that degrade osteoid thus exposing bone for osteoclasts to work on Reversal lines marks the change in bone activity. Constant remodelling to adapt to pressure
36
What are the sharpey's fibres?
Extrinsic fibres. They enter the bone perpendicular to the surface. Less numerous but thicker than those in cementum. Two main appearances under SEM (anorganic): Fibres remain unmineralised at their centres, resulting in hollow centres. Fully mineralised project beyond bone surface as small calcified prominences
37
What is the gingiva
The portion of the oral mucosa that surrounds and is attached to the teeth. Two main regions: The attached gingiva: directly bound to the underlying bone and tooth The free gingiva: narrow, not bound to any bone The free gingival groove demarcates the free from the attached gingiva (40% of teeth) The gingival margin is the coronal limit of the free gingiva The gingival sulcus is the unattached region between the free gingiva and the tooth The junctional epithelium is the area where the gingiva is bound to the tooth
38
What are the characteristics of of the gingiva
The free gingival groove follows the contour of the cemento-enamel junction. Principal fibres running from cementum to the gingiva. Heavy epithelial ridges. Healthy gingiva shows stippling, corresponding to epithelial ridges
39
What is the free gingiva?
The free gingival mucosa is identical to the attached gingiva. The gingival sulcus is 0.5-2.0mm deep in healthy gingiva. Sulci deeper than 3.0mm are considered periodontal pockets
40
What is the sulcular epithelium?
Sulcular and junctional epithelia form the ginigval cuff. Sulcular epithelium has a more folded interface with the lamina propria. Sulcular epithelium is thin. The base of the sulcus is at the same level as the free gingival groove
41
What is the junctional epithelium?
Junctional epitheliumextends from CEJ to the sulcus base. 2mm. Thinner apically. 5-6 days turnover rate
42
What is the crevicular fluid?
The gingival crevicular fluid is the fluid within the sulcus. Results from the permeability of the junctional epithelium. Important in the defence mechanism
43
What is the interdental papilla?
The interdental gingiva occupies the area between adjacent teeth. Its shape and size depend on the shape and contact between teeth. Wedge shaped appearance on the buccal and lingual sides. Pointed between anterior teeth. The interdental col a curved depression across the buccolingual plane. It fills the contour around the contact point
44
What is the col?
The epithelium of the col is continuous with the junctional epithelium. Spaced teeth have no col
45
What is the gingival lamina propria?
Dense collagen bundles: Support the free gingiva. Bind the attached gingiva to the alveolar bone and the tooth. Linkage of teeth to each other. Principal fibres divided into groups according to their location
46
What are the names of the fibrs present in the gingival lamina propria?
``` Dentoginigval fibres Longitudinal fibres Circular fibres Alveologingival fibres Dentoperiosteal fibres Transseptal fibres Semicircular fibres Transgingival fibres Interdental fibres Vertical fibres ```
47
What are cementicles?
Excess growth of the cementum which enters the PDL, or reduces the amount of attached gingiva

CSP3 YR5- Restorative (44 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions