Pulp A Flashcards
Define the following:
- alveolar bone
- peridontal membrane/ peridontal ligament
- Cementum
- dentine
- Alveolar bone = the bone that holds the tooth
- peridontal ligament/ membrane = the ligament that attaches the tooth to the alveolar bone
- cementum = covers the dentine on the root of the tooth
- dentine = covers the pulp.
What is the pulp-dentine complex & why is it important?
- basically the pulp and dentine.
- pulp has fibrous connective tissue
- dentine has calcified connective tissue
- anything that happens to dentine happens to pulp & vice versa
- they are linked embryologically, structurally & functionally
What are the anatomical boundaries of pulp?
- accessory/ furcation canals = canals in the dentine in the root area
- apical foramen = the foramen at the apex of the root, which allows entry of blood vessels to the tooth.
- root canal systems.
What is tissue composition of the pulp & what is are they composed of?
1) cells
- odontoblasts
- fibroblasts
- immune cells (macrophages, dendritic cells, lymphcytes - T & B)
- undifferentiated mesenchymal cells
2) extracellular matrix
- ground substance
- collagen
- interstitial fluid
3) blood vessel & nerves
- blood vessels: venules & arterioles
- nerves: sensory afferent & sympathetic efferent
What cells are in the pulp & what are their functions?
1) odontoblast = have projections that extend down the dentine tubules.
- form & maintain dentine
- transducer between external stimuli and pulp sensory nerves.
- sense antigen & hormones
2) immune cells
- immune surveillance
- induce T cell dependent immunity
3) fibroblasts
- most numerous in the pulp
- produces extracellular matrix
4) undifferentiated mesenchymal cells
- present throughout the pulp
- moves to areas of injury and replace destroyed odontoblasts.
What does the extracellular matrix in the pulp contain?
- ground substances = a structureless mass making up the bulk of the pulp tissue.
- collagen fibres = major component of the pulp. Most dense near the apex.
- interstitial fluid = fluid that surrounds cells
What are the morphologic zone of the pulp?
1) Odontoblast layer
2) Cell-poor zone
3) Cell-rich zone
4) pulp proper
What does ground substance contain?
1) hydrogel
- supports cells
2) proteoglycan
- adhesive for cells
3) hyaluronan
- unbranched random coil large polymers
What types of collagen fibres are in the pulp?
- type I collagen
- type III collagen
Describe the morphologic zone of the pulp?
1) odontoblast layer
- outermost layer next to the predentine
- lined by single layer of cell bodies
- contains odontoblast cell body, capillaries, terminal nerve axons & dendritic cells
2) cell-poor zone
- subjacent to odontoblast layer
- free of cells
- contains plexus of Raschkow, rich capillary plexus, fibroblast processes
3) Cell-rich zone
- high density of fibroblasts
- contains fibroblasts, undifferentiated mesenchymal stem cells & immune cells (macrophage & dendritic cells).
4) Pulp proper
- large blood vessels
- nerve axon bundles
- contains fibroblast, undifferentiated mesenchymal cells, immune cells (macrophage, dendritic cells & lymphocytes)
What blood vessels & nerves are in the pulp?
1) blood vessels
- arterioles
- venules
2) Nerves
- sensory afferent (majority)
- sympathetic efferent
What are the anatomical boundaries of dentine?
1) Dentinoenamel junction (DEJ)
- between dentine & enamel
- increase contact & adherence between dentine & enamel
- keeps D & E together during mastication
2) Dentinocemental junction (DCJ)
- border between dentine & cement
- mineralised collagen fibres continue from cementum to dentine
- cementum meets dentine at apical foramen
3) cementoenamel junction (CEJ)
- location where cementum overlaps/ covers enamel
- location is according to cementum. it can overlap enamel or expose dentine.
What is dentine composed of?
- carbonated hydroxyapatite -> inorganic fraction
- collagen type I -> organic fraction
- free & bond water -> water
What are the tissue composition of dentine?
1) cell processes -> odontoblast process
2) nerves -> sensory afferent
3) extracellular matrix
a) collagen fibres -> collagen type I
b) ground substances -> proteins, enzymes, growth factors & serum proteins
c) apatite crystal filler particle
- hydroxyapatite crystal filler particles are intrafibrillar & interfibrillar mineralisation within & between collagen matrix.
- Calcospherites
d) dentinal fluid -> ultrafiltrate of blood from the pulp capillaries.
What are the microstructure of dentine?
1) dentinal tubules
- tubules that extend through the entire thickness of dentine.
- S-shape in coronal dentine & straight in root dentine
- less near DEJ, more near the pulp
- tapered structure -> narrow at DEJ & wide at the pulp
2) odontoblast processes
- formation = odontoblasts extend several
3) intertubular dentine vs peritubular dentine
What is the difference between intertubular and peritubular dentine?
1) intertubular dentine = located between dentinal tubules
2) peritubular dentine = encircles each dentinal tubules
What is sclerotic dentine & interglobular dentine?
1) Sclerotic dentine = tertiary dentine
2) Interglobular dentine = hypo or unmineralised areas
What are the different types of dentine?
1) Mantle dentine
- first dentine to form by new but not fully differentiated odontoblasts.
2) Predentine
- located between odontoblast and mineralised dentine
3) Primary dentine
- formed prior to eruption
4) Secondary dentine
- formed after eruption
5) Tertiary dentine
- formed in response to injury
What is odontogenesis?
- formation & eruption of teeth & integrating it within its surrounding tissues.
What are the 4 stages of odontogenesis?
1) Lamina
- Ectoderm (oral epithelium) thickens & buds into the ectomesenchyme at 5 weeks, along the maxillary & mandibular arches, where the teeth will develop.
2) Bud
- Dental lamina/ oral epithelium continues to grow and thickened to form a Bud
- Cells of the ectomesenchyme proliferate and condense underneath & forms dental papilla.
3) Cap
- Dental lamina grows to encompass ectomesenchymal growth - forming a cap or tooth germ.
- condensed ectomesenchyme -> dental papilla
- oral epithelium -> enamel organ
- surrounding condensed ectomesenchyme becomes dental follicle
- Enamel knot is a signalling centre -> regulate crown morphogenesis.
4) Bell
a) Early bell stage
- undifferentiated mesenchymal cells undergo mitosis -> become ameloblast & odontoblast
- ameloblast -> forms enamel
- odontoblast -> forms dentine
b) Late bell stage
- dental papilla -> dental pulp
- predentine is formed
How are the roots formed?
- roots form after the completion of enamel formation
- root formation marks the end phase of odontogenesis.
What is the cervical loop?
- a histological term indicating an epithelial structure at the apical side of the tooth.
- it consists of loosely aggregated stellate reticulum in the center surrounded by stratum intermedium.
What is the Hertwig’s epithelial root sheath?
- after the completion of the enamel formation, the stellate reticulum & stratum intermedium cells disappear -> forms the root sheet that is a barrier between dental papilla & follicle.
When do the primary and secondary dentition erupt?
- primary dentition -> 6 months to 2-3 years
- secondary dentition -> 6 years to 12 years.
