W7 Dentine + pulp Flashcards
What is dentine?
Consists of large number of small parallel tubules in a mineralised collagen matrix. Odontoblasts are responsible for production of dentin
What physical properties does dentin have?
- Pale yellow colour
- Permeable
- Higher degree of tensile and flexural strength than enamel
What are the chemical properties of dentin?
50% mineral
25% Water
25% organic
What dentin composed of?
Inorganic - hydroxyappatite minerals
Organic - collagen fibres
Water
What is composed in the organic matrix?
collagen fibers, proteins, dentine phosphoproteins, GLa-proteins, acidic proteins, growth factors, lipids
What is the inorganic matrix composed of?
Hydroxyappatite crystals, fluoride, strontium,
Where do Dentine Tubules run?
Run from pulpal surface to DEJ
What is the S curves?
Segmoid primary curvatures
- Rootward convexity near the pulpal surface
- Almost straight in the root and beneath the cusps
What is the Secondary Curvature?
Contour lines of Owen they coincide in adjacent tubules, branching and looping gives the granular layer of Tomes in the root
What is peritubular dentine?
Deposited by the processes on the walls and narrowing of the dentinal tubules, lacks collagenous fibrous matrix
Describe Odontoblasts and Processes
Become embedded in the ECM, elongates as the odontoblast moves toward pulp. It also stimulates differentiation of ameloblasts
What types of dentin present?
Primary
Secondary
Tertiary
Describe the function of primary dentine
Formed prior to eruption, deposited at DEJ, contains incremental lines. Contains: mantle dentine, circumpulpal dentine, globular dentine, peritubular, intertubular.
Describe the function of Secondary Dentine
Formed after completion of root formation, deposited more slowly than primary dentine, deposition leads to decreased of of pulp chamber
Describe the function of Tertiary dentine
Forms if dentine subjected to trauma, irritation, carious dentine, traumatic cavity prep.
- Irritation
- Irregular secondary
- Reparative
Define Reactionary dentine
Tertiary - dentine forming in response to insult, damage, but exisiting cells recover
Define Reparative
Teritary - Dentine forming in response to an insult, original odontoblasts destroyed - produces tissue
What 3 layers of dentine are located in crown?
- Mantle dentine
- Interglobular dentine
Circumpulpal dentine
What 3 layers are located in the root?
Hyaline layer
Granular layer of Tomes
Circumpulpal dentine
Define mantle dentin
First depositied around the dentinoenamel junction, lacks dentin sialoptotein in the mineralising ECM
Define Circumpilpal dentine
Layer of dentine around the outer pulpal wall, makes up bulk of tooth. Formed and matured after mantle dentin. In the crown its beneath matle and interglobular dentine
In the root: beneath the granular layer of Tomes
Define Globular Dentine
Between mantle and circumpulppal, only in the coronal portion of the tooth, the dentineis calcified following formation of the matrix and calcification occurs in small spherical space
Define peritubular
Immediately surrounds dentinal tubule, higher mineral content and lacks collagenous matrix
Define Intertubular
Forms bulk of dentine, around dentinal tubules of crown and root, less mineralised than peritubular
Define Hyaline layer
Most peripheral layer of initially unmineralised dentine, aids cemenum in binding to the dentin
Define Granular layer of Tomes
In the root, just beneath the hyaline layer and cementum
Whats the difference between interblobular dentine vs Tomes granular layer?
Seen in crown, and higher sulfur, Tomes seen in root, calcium + phosphorus
What is predentine?
The inner most layer of dentin, thicker in young teeth, non-mineralised, secreted by odontoblasts via golgi apparatus, mitachondria
What is translucent dentine?
Forms with aging due to tubules occlusion by peritubular dentine, pronounced at root apex
Define Sclerotic dentine
Tubular occulsion by stimulus at site, tubules are completely obliterated. It is believed to be protective mechanisim to pulp
What are dead tracts?
Odontoblastic processes killed by a stimulus, empty tubules
What is the extent of odontoblast process?
Odontoblast dont go fully into the tubules, plays a role in dentine sensitivity
What is deep dentine?
Secondary dentine - tubular surface area increase, difficult bonding to deep dentine
What are incremental lines?
Lines of Von Ebner - cross striations across dentinal tubules
Controur lines of Owen - Follows a pattern, DEJ meet the accompanying striae of Retzius
What lines are associated with primary curvatures?
Schreger lines
What lines are associated with secondary curvatures?
Contour lines of owen
What are the 3 pulps?
Coronal Pulp
Radicular Pulp
Apical Foramina and Accessory canals
What is the coronal pulp?
Occupies crown of the tooth, larger than root pulp, pulp horns extend into cusps of tooth
What is the Radicular Pulp?
Extends from cervical regions to apex
What is the Apical Foramina & accessory canals?
Apical foramen: opening of root pulp into periodontium
Accessory canals may result from presence of blood vessels obstructing dentin formation
What is pulp?
Soft specialised connective tissue loacted in the central portion of the tooth
What is the function of the pulp?
Inductive
Formative
Protective/defence
Nutritive
Describe Induction in the role of the pulp
In early development interacts with oral epithelium to initiate tooth formation
Describe Formative in the role of the pulp
Odontoblasts from dentine
Describe the roles of protection in pulp
Formation of reparative dentine, inflammatory response
Describe Nutritive role of the pulp
Carries oxygen and nutrition to the tooth
What is the composition of the pulp?
Connective tissue: Type 1 collagen fibres (ground substance, macromolecules and fluid
Cells: Mesenchymal cells (fibroblasts, macrophages, odontoblasts)
Neurons
Transient cells
Endothelial cells
Has no fat cells
What is the Odontogenic Zone?
Odontoblast layer
Cell free zone
Cell rich zone
Central pulp
Define the odontoblast layer
Outter most layer - Forms a single pseudostratified layer of cells attached to predentine surface
Define Cell free zone?
Immediately beneath odontoblast layer
Define Cell rich zone
Deep to cell free zone, high concentration of capillaries and exons, fibroblasts and mesenchymal cells
Define central pulp
Bulk, and neurvascualar core
Name 3 pulp cell types
Odontoblasts, Fibroblasts, Schwann cells, endothelia
Define odontoblasts
They line perimeter of pulp from time they begin organizing to form dentin to the time they are no longer producing dentin at a rapid rate
Define Fibroblasts
Are the most numerous cells in pulp, protein-producing cell, get smaller with aging
Define Schwann cells and endothelial cells
SC form myelin sheath of nerves and associated with all pulp nerves
EC lines capillaries, veins and arteries of pulp
What is the effect of restorative procedures?
Traumatic cavity prep, more rapid dentinogensis, growth factors incorporated into mineralized dentine matrix are released during carious invasion to induce dentinogenesis
What are the dynamics of pulpodentine complex
Exposed fluid-filled tubules allow minute fluid shift across dentine in tactile, thermal, osmotic or evaporative stimuli - vitality test, thermal changes H/C
What reaction occur ‘inwardly’ during cavity prep? (fluid shift)
Frictional head
- Osmotic movement of cooling water
- Heat generated due to LC
What reaction occurs ‘outwardly’ during cavity prep? (fluid shift)
Evaporation by air cooling or air blow
Applying hypertonic conditioners, primers, bonding agents and varnishes
What do fluid shifts create?
Pain in unanesthesized pulps
Local pulp inflammation under irritated tubules
Increases in tissue pressure
Alteration in pulpal blood flow
Name disruption of odontoblastic layers
Restorative procedures
Deep prep can aspirate odontoblasts
Shallow preps distrupt junctional complexes between odontoblasts, by allowing large molecules to penetrate pulp, loss of cell signalling
