The Dentino-Pulpal Complex Flashcards
Dentine - basic overview?
Overview:
- forms the bulk of the tooth
- large number of parallel tubules in a generalised collagen matrix
- tubules contain the processes of odontoblasts
- sensitive
- formed throughout life
Dentine - physical properties?
Physical properties:
- fresh dentine is pale yellow
- harder than the (_______) cementum
- softer than the enamel
- permeable, depending on the latency of the tubules
Dentine - chemical composition - inorganic and organic overview?
- Dentine is 70% inorganic, 20% organic and 10% water
Inorganic composition: - calcium hydroxyapatite; are Ca poor and carbonate rich
- much smaller than enamel hydroxyapatite
- found in and between collagen fibrils
Organic composition: - Col I forms 90%
- DPP and proteoglycans also present
Hexagonal shaped crystals
Dentine - chemical composition - organic matrix? composition? Phospphoryn? Proteoglycans and role? Other present proteins? GF? Lilies?
Organic matrix:
- 90% of organic matrix (Col I)
- phosphophoryn (PP-H); main phosphoprotein (most acidic) and high calcium binding properties (implicated in mineralisation)
- main proteoglycans in dentine are bigkycan and decorin
- proteogly role in collagen assembly, cell adhesion, migration, differentiation and proliferation (role in mineralisation)
- GAGs also present
- y-carboxyglutamate-containing proteins in dentine
- bind strongly to hydroxyapatite crystals (role in mineralisation)
- acidic proteins; osteonectin, osteopontin present
- GF: IGF and TGF
Lipids:
- 2%
- phospholipids involved in formation and growth of apaptite crystals
Dentine tubules - location? Shape? Presentation? Xsec? Between tubules? Size changes and why? Secondary curvature? Branching?
Location: - extend from the pulp surface to the amelo-dentinal and the cementi-dentinal junctions Shape: - curved sigmoid course Presentation: - form primary curvature of dentine Xsec: - circular Between tubules: - intertubular dentine Size changes: - 2.5um at pulpal end and 1um at enamel end Why: - odontobalsts retreat inwards, occupy a smaller area, and so the tubules become closer together Secondary curvatures: - coincidenwith adjacent tubules gove risento contour lines of Owen Branching: - branch near the enamel-dentine junction - in root, terminal branches loop - more obvious in predentine
Dentine tubules - intratubular dentine - characteristics? Formation?
Formation:
- walls of newly formed dentinal tubules at the pulp surface are made of Col I
- maturation of tubules assoc with deposition of another type of dentine in walls
- reduction in lumen (can be complete obliterated)
- called intratubular dentine
Intratubular dentine - characteristics? Differences to inter?
- lacks collagen matrix
- increased radiographic and electron density (15% more mineralised)
Intratubular dentine - inorganic component? physiological ageing?
Inorganic component:
- carbonated appetite with a different crystalline form
- hypocalcified areas
Physiological ageing:
- leads to complete obliteration of tubules with intratubular dentine (root dentine)
- appear translucent in water (butterfly Xsec, due to convergence of of tubules)
Contents of the dentinal tubules - odontoblastic processes - structure differences? Organelles? Location?
Structure differences:
- variable structure at various levels
Organelles:
- more in predentine area
- presence of microtubules and intermediate filaments
Location:
- inner layers of dentine, the processes occur the full width (remnants of processes seen in the peripheral parts of the tubules (after it has degenerated)
- degeneration of peripheral end (theory for withdrawal of odontoblasts
Contents of the dentinal tubules - afferent nerve terminals - location? Relationship? Organelles?
Location: - inner layers of dentine Relationship: - with the odontoblastic proces Organelles: - mito and vesicles
Contents of the dentinal tubules - sensory terminals - location? Size? Organelles?
Location: - coronal dentine beneath cusos (in 80% of tubules) - sparse in cervical and root dentine Size: - narrower than odontoblastic processes Organelles: - microtubles and microfilaments
Contents of the dentinal tubules - antigen presenting cell processes - appearance? Role? Location?
Apperance: - small processes in the tubules near pulp Role: - immunocompetent APC Location: - within and beneath odontoblasts - processes limited to predentine - extends deeper in tubules under caries
Contents of the dentinal tubules - extracellular dentinal fluid - brief composition? Role? Pa?
Composition:
- higher K and lower Na in comparison
Role:
- this balance affects the membrane properties of cells
Pa:
- positive force from the pulpal tissue pressure
Mantle dentine - formation order? Size? Differences from circumpulpal dentine?
Order: - most peripheral layer of dentine (1st) Size: - 20-150um Differences: - 5% less mineralised - Col fibres perpendicular in the amelo-dentinal junction - branching of tubules - different mineralisation process
Interglobular dentine - shape? Fusion? Location?
Shape:
- minerals deposited as globular (calcospheres)
Fusion:
- form a uniform calcified tissue
Location:
- beneath mantle dentine (incomplete fusion)
- undercalcified interglobular areas appear dark
- tubules pass areas
Granular layer of Tome - what is it? direction? Role? Apperance?
What is it: - peripheral root dentine had a dark granular layer Direction: - dentinal tubules branch and loop back on themselves Role: - create air spaces Apperance: - tree top appreance of tubules - hypimineralised granular layer - incomplete fusion of calcospherites
Dentino-pulpal complex - Hyaline layer - located? Width? Structure basic? Helps with?
Location: - outaidenthe granular layer Width: - 20um Structure: - atubular and structureless Helps: - in binding dentine to cementum
Dentino-pulpapl complex - Circumpulpal dentine - main? Structure basic?
Main:
- bulk of the dentine
Stricture:
- uniform except at peripheries
Dentino-pulpapl complex - predentine - when laid down? Structure during mineral? Width?
Laid down: - prior to mineralisation Structure during mineralisation: - show a.globular or linear apperance Width: - 10-40um Thicker in younger teeth
Dentino-pulpapl complex - structural lines in dentine? Primary curvature? Secondary curvature? Incremental lines?
Primary: curvatures of dentinal tubules; - Schreger lines Secondary: curvatures of dentinal tubules; - contour of lines of Owen Incremental lines: - von Ebner's lines - Andresen lines
Dentino-pulpapl complex - primary curvature lines (Schreger lines)? Section cut? Difficulty?
Section cut:
- longitudinally
Difficulty:
- to see in cross sections
Dentino-pulpapl complex - secondary curvature lines (contour lines of Owen)? Location?
Location:
- exaggerated line on the border of primary and secondary dentine
- neonatal line
Dentino-pulpapl complex - Von Ebner’s lines - location and size?
Von Ebner’s Lines:
- cusp dentine: 4um separate every 2 lines
- root dentine: 2um separate every 2 lines
Dentino-pulpapl complex - Andresen Lines - size apart? lines found in-between?
Size: - 16-20um apart Lines found inbetween: - 6-10 lines of Owen between every 2 Andresen lines Exaggerated neonatal line
Dentino-pulpapl complex - physiological age changes? changes associated with dentinal responses to stimuli?
Physiological changes: - secondary and translucent dentine Changes associated to dentinal responses to stimuli: - tertiary and sclerotic dentine - dead tracts of Fish
Dentino-pulpapl complex -
Secondary dentine - start formation? similar structure? differences to primary?
Start formation: - form once the root is completed and the tooth comes into occlusion Similar structure: - to primary dentine Differences: - sudden change in tubule direction - slower deposition thus less regular - closer incremental lines Close to pulp
Dentino-pulpapl complex - Translucent dentine - how it occurs? location?
How it occurs:
- obliteration of tubules with intratubular dentine
Location:
- root dentine
Dentino-pulpapl complex - Tertiary dentine - stimuli? types of dentine formed? variable appearance? differentiation? production of? interactions? Factors released (induces)
Stimulus: - external (trauma) induce the pulp to produce more calcified material Dentine formed: - irregular secondary dentine, reparative dentine, reactionary dentine, response dentine and osteodentin Variable appearance: - tubular, irregular and atubular Differentiation: - pulp cells into odontoblasts - or original odontoblasts Production of: - Col I and dentine sialoprotein Interactions: - epith-mesenchymal interactions Factors released during inflammation?
Dentino-pulpapl complex - Sclerotic dentine - stimuli? similar structure? different composition? composition? exposed tubules?
Stimuli: - induce the deposition of material inside the tubules (forming sclerotic dentine) Similar structure: - to transparent dentine Diff composition: - from intratubular dentine Composition: - apatite crystals and octacalcium phosphate crystals Exposed tubules: - might contain components from saliva
Dentino-pulpapl complex - Dead Tracts of Fish - formed by? Sealed? defintion?
Formed by:
- primary odontoblasts killed (external stimuli)
- could retreat before form of intratubular dentine (forming empty tubules)
Sealed:
- at their pulpal end by tertiary dentine
- air filled, thus light will be internally reflected and they will appear dark
Definition:
- is the term given to these air filled tubules
Dentino-pulpapl complex - Dentine sensitivity - different stimuli? food related stimuli? sensitivity due to? hydrodynamic theory? outward/inward movement stimuli?
Different stimuli:
- cold air/water
- mechanical contact (bur, probe)
- dehydration (cotton, air)
- heat produced during drilling
- chemicals
Food related:
- thermal changes
- osmotic changes
sensitivity due to:
- nerve endings in the dentine
- odontoblastic process
- movement of fluid within dentinal tubules
Hydrodynamic theory:
- stimuli applied to dentine cause fluid movement
- sufficient to depolarise nerve endings (in tubules, dentine-pulp junction and in plexus of Raschkow)
- stimuli cause outward movement of fluids (heat, osmotic pressure and drying)
- cold stimuli causes inward movement of fluids
- both movements affect nerve terminals
- tubular branching near DEJ explain higher sensitivity
- removing intracellular fluid disables a fibres
Dentino-pulpapl complex - Dental pulp - general organisation (contained, continuous, what is it, composition basic), composition of pulp? Pulp fibres? Fibre formation?
General organisation:
- pulp contained within the pulp chambers and root canals
- apically, the pulp becomes continuous with the PDL
- specialised CT
- odontoblasts lie on peripheries, nerve terminals, APCs and BVs
- each root has one canal
- accessory canals apical third
Composition of pulp:
- cells in ECM
- 75% water and 25% organic
- fibres and non-fibrous matrix
- Col main component
Pulp fibres:
- Col I; fibrils thinly and randomly scattered, at the peripheries, parallel to predentine and right angles to the amelodentinal junction in mantle dentine (von Korff’s)
- Col III; in large amount, random scatter, only a1 chains and 41% pulpal collagen
- V and VI and fibrillin
Fibre formation:
- alpha chain (3)
- form procollagen (procollagen peptidase)
- collagen molecule
- assembles collagen fibril
- assembles fiber
Dentino-pulpapl complex - pulp - nonfibrous matrix - GAGs (definition and types)? Proteoglycan (definition and types)? and adhesion molecules?
Non-fibrous matrix:
- GAGs; polysaccharide chain, bulku hydrophilic molecules from gel (chondroitin sulphate predominates also dermatan and heparan, also hyaluronan)
Proteoglycans: core protein surrounded by GAGs
- decorin (bind Col and TGFb)
- biglycan (reg Col fibrinogen)
- versican (proteogly aggreg)
- syndecan (attach to Col)
- Tensascin (cell adh)
Adhesion molecules: integrin
- fibronectin (cell attach to ECM, and cytoskel, reg cell shape, mig and diff)
- laminin (base mem and binds epith to ECM, bind sig mole, odontoblastic bodies and processes coated with laminin)
Dentino-pulpal complex - Dental pulp - odontoblasts (description of cell, location, shapes in diff sections and cell junctions)
Odontoblasts:
- fully differentiated, polarised columnar cell with a long process inside a tubule
- cell body (50umx5-10um)
- small processes link adj odontoblasts and other pulp cells
- form a layer of single cells attached to the predentine (by single process)
- coronal odonto are columnar in outline, cuboidal in root
- oblique section (appear pseudostratified)
Cell junctions:
- desmosomes, tight junctions and gap junctions
Dentino-pulpal complex - dental pulp - fibroblasts (location, production and degrad)
FIbroblasts:
- scattered in pulp
- slowly produce fibres and GS
- pulp fibroblasts degrade ECM
- matrix turnover
- can produce hard tissue
- prod of GFs and cytok
- apoptosis
Dentino-pulpal complex - dental pulp - immune cells - (T-lympho, macro and APC)
T-lympho: - small numbers increases during injury Macrophages: - diff morpho in rest form - widely distributed and large numbers - denser around BVs and odontoblast APCs: - 3 or more branching processes - numerous around BVs and odonto - induce lympho prolif and mig to lymph nodes
Dentino-pulpal complex - dental pulp - undifferentiated cells (location and name?
- beneath the odontoblastic layer capable of diff into odonto
- pluripotent primitive mesenchymal cells could diff into cell variety
Dentino-pulpal complex - dental pulp - BVs (relation, enter, course, branching, location, anastomoses, vasoconstrictor, blood flow)?
Relation:
- with nerves
Enter: arterioles and venules
- via the apical foramen and lateral canals
Course:
- run inside the root canals giving branches to the peripheries
Branching:
- within the coronal pulp chamber
Location:
- subodontoblastic capillary plexus (within and beneath odonto)
- base mem
Anastomoses:
- arterio-venous and venous-venous
Lymph vessels
Vasoconstrictor nerve endings in association with arteriole smooth muscle
Blood flow 2-60ml/min per 100g of tissue (high fluid Pa)
Dentino-pulpal complex - dental pulp - nerve fibres (axons, myelination, fibre type, structure, enter)
Axons:
- 2500 enter a mature premolar
Myelination:
- 25% myelinated afferents
Fibres:
- 90% of which are Adelta fibres
- Adelta thin myelinated axons with a moderate conduction velocity (assoc with acute pain and temp Pa)
- remainder are Abeta fibres
- afferent fibres that carry non-noxious sensations
- unmyelinated C fibres majority (slow conduction, chronic or dull pain with sensations of warmth, mechanical and chemical)
Enter:
- as part of the neurovascular bundle
- branches end in and around odonto layer
- plexus beneath odonto (Raschkow)
Dentino-pulpal complex - dental pulp - nerve fibres (branches, facilitates, vasodil)
Branches: - enter dentinal tubules - many axons in tubules, at peripheries of dentine and among odonto bodies are devoid of schwann - facilitates response to stimuli Vasodilator: - CGRP is potent vasodilator - control pulpal blood flow - synth by neurons and transported by axons - control hard tissue form - nerve in pulp maintain local environ
Dentino-pulpal complex - dental pulp - regions?
Regions:
- supraodonto region
- odonto layer
- subodontoblastic (cell free zone of Weil and cell rich zone)
- Bulk of pulp
Dentino-pulpal complex - dental pulp - supraodonto region (location, appear due, axons, tubules)
Location:
- between odontoblastic cell bodies and the predentine
Appear due:
- to tissue shrinkage
Axons:
- unsheathed axons are present (predentinal plexus of Bradlaw)
Tubules:
- where changes in tubules can be detected
Dentino-pulpal complex - dental pulp - Cell free zone of Weil (processes, location)
Processes:
- fibroblasts, odonto, axons and capillaries
- anuclear zone
- only in coronal pulp of erupted teeth
Dentino-pulpal complex - dental pulp - cell rich zone (plexus, cell associated)
Plexuses: - subodontoblastic capillary plexus - subodontoblastic neural plexus Cell associated: - with these plexi could result in the richness of this zone
Dentino-pulpal complex - dental pulp - bulk of pulp (description)
Description:
- central area of pulp
- loose CT
- rich blood and nerve supply
Dentino-pulpal complex - dental pulp - ageing of pulp? (what occurs, calcification)
Ageing of pulp: - pulpal size decreases - decreased vascularity - more fibrous - reduced innervation Calcification: - pulp stones
Dentino-pulpal complex - dental pulp - pulp stones (#, denticles, attached, complications)?
Pulp stones:
- single or groups
- true denticles resemble dentine (tubular)
- false denticles resemble bone (trapped cells)
- stones attached to dentine
- complication of root canal therapy
Dentino-pulpal complex - dental pulp - clinical considerations?
Clinical considerations:
- defects mediate through pulp
- pulp inflamm (pain and difficult to localise)
- exposure of lateral canals to the oral environ
- exposure to cavity prep
- root canal treatment
- transformation into granulation tissue following trauma, leading to resorption to dentine by odonto
- internal resorp of pulp
- pinkish colouration of tooth
