Physiology of the Pulp Flashcards
Describe the basic physiological features of a tooth
- Enamel as the outermost layer
- Dentine comes next
- Pulp comes next
- PDL and periodontal membrane present outside root dentine
- Cementum attaches PDL to dentine
Describe 4 features of the form of dental pulp
- Loose connective tissue in tooth
- Made up of combination of cells in ECM of fibres
- Enclosed by dentine except at apex where continuous with PDL
- Relatively small volume in tooth
Name 3 functions of the dental pulp
- Maintain health of dentine by providing nutrients
- Provides pathway for sensory impulses
- Initiates and controls repair of dentine when damaged
What 2 things make up the pulp?
- ECM / Ground substance
2. Cells
What part of the pulp is responsible for the water-holding properties?
ECM
Name 3 types of glycoproteins in the dental pulp
- Proteoglycans
- Glycosaminoglycans (GAGs)
- Fibronectin
What are proteoglycans?
Consist of a core of proteins surrounded by GAGs
What are GAGs?
Long chain carbohydrate molecules which retain water to form a gel
What is the role of fibronectin?
Major role as an anchor protein
What are 2 types of structural proteins found in the pulp?
- Collagen
2. Elastin
Describe collagen as a component of the pulp
Makes up around 1/3 of dry weight of pulp and confers structure to tissue by maintaining position of vessels, nerves and cells
Describe elastin as a components of the pulp
Present only in the walls of blood vessels of the dental pulp
Name 4 types of cells found in the pulp
- Odontoblasts
- Fibroblasts
- Defence cells
- Stem cells
Describe odontoblasts found in the pulp
- Form outermost stratum of cells in healthy pulp
- Most highly differentiated cells of pulp
- Produce components of predentine and dentine including collagen
- Series of specialised junctions between adjacent odontoblasts
Describe 2 components of the ultrastructure of mature odontoblasts in the pulp
- Cytoplasmic process which extends into dentinal tubule
2. Smaller processes link odontoblast with neighbouring odontoblasts and fibroblasts
Describe fibroblasts found in the dental pulp
- Most numerous cell type found
- Produce gelatinous matrix in which all components are embedded
- Produce collagen fibres which reinforce ECM
- Produce MMPs which degrade collagen and proteoglycans
Name 4 defence cells of the pulp
- Macrophages
- Dendritic cells
- T-lymphocytes
- Mast cells
Describe the location and function of macrophages in the dental pulp
- Found around blood vessels of inner pulp and odontoblast layer
- Phagocytose dead cells and foreign bodies
Describe the location and function of dendritic cells in the dental pulp
- Subjacent to the odontoblast layer in perivascular regions
- Monitor invasion of antigens
Describe the volume o T-lymphocytes in the dental pulp
Present in small numbers but increase when pulp is injured or exposed to noxious stimuli
Describe when mast cells are routinely seen in pulp
Routinely found in chronically inflamed pulp
Where are stem cells found in the pulp?
Along capillaries in cell rich zone and to a lesser extent throughout the pulp
Describe the pulpal vasculature
- Arterioles and venules enter dental pulp in neurovascular bundle via apical foramen
- Divide and narrow to some degree in root canals
- Branch profusely in coronal pulp
Name a unique feature of the pulp with regards to expansion
It is rigidly encased within the dentine which is a low compliance environment with limited ability to extend
Describe how the pulp is innervated
- Sensory nerves arise from trigeminal nerve
- Pass into radicular pulp via apical foramen
- Closely associated with blood vessels
In what form do nerves enter the apical foramen?
Bundles
Name 2 types of nerves found in the pulp
- A-fibres (myelinated)
2. C-fibres (unmyelinated)
What are 2 types of A-fibres found in the pulp?
- Aβ
2. Aδ
What type of sensation is conveyed by A-fibres?
Sharp, penetrating, short lasting sensations
Name 3 things which activate myelinated nerves in the pulp
- Air (Aδ)
- Hot / Cold (Aδ)
- Vibration (Aβ)
Where are A-fibres found in the pulp?
Abundant at the pulp-dentine junction
Where are C-fibres found in the pulp?
Abundant in the pulp proper
Name 3 things which activate C-fibres in the pulp
- Inflammatory mediators
- Mechanical deformation
- Heat
Describe 3 differences between dentinal and pulpal pain
- Dentinal pain consequence of external stimulus whereas pulpal pain is usually inflammatory in origin
- Dentinal pain brief and sharp whereas pulpal pain has prolonged time course
- Dentinal pain arises as a result of A-fibre activation whereas pulpal pain arises as a result of C-fibre activation
How are dentinal tubules related to dentinal pain?
Dental pain involves fluid movement in the dentinal tubules
Describe the lumen of the dentinal tubules, especially with regards to enamel junction and pulpal junction
- Inverted cone shape
- Lumen narrow at the enamel junction due to present of peritubular dentine
- Lack of peritubular dentine at pulpal boarder so tubules are wider here
Describe the morphological zones of pulpodentine complex from the outside in
- Dentine
- Odontoblast layer
- Cell free zone
- Cell rich zone
- Pulp proper
Name 2 reasons the pulp decreases in size with age
- Deposition of secondary dentine throughout life
2. Development of tertiary dentine in response to caries
Describe repair of the pulp, including how this changes with age
- Local circulation critical to healing
- Highly cellular young pulp much better healing potential than older tooth
- Reparative dentine deposited at sites of irritation
- Dentine becomes inert when pulp removed or necrotic
