Oral biology excel Flashcards
What does the dental pulp originate from?
The dental papilla and is enclosed by the enamel organ.
What cells does the dental pulp contain?
- Granulocytes: The most common leukocyte in dental pulp, making up about 50% of the total
- T lymphocytes: Make up about 32% of the total leukocytes in dental pulp
- Monocytes/macrophages: Make up about 9% of the total leukocytes in dental pulp
- Dendritic cells: Make up about 4% of the total leukocytes in dental pulp
- Natural killer cells: Make up about 3% of the total leukocytes in dental pulp
- B lymphocytes: Make up about 2% of the total leukocytes in dental pulp
Other cells found in dental pulp include:
Odontoblasts
Fibroblasts
Mast cells
Undifferentiated mesenchymal stem cells
Nerves
Vascular and perivascular cells
What types of collagen is the pulp rich in ?
Collagen I (60%)
Collagent III (40%)
What are rules of the pulp: (4)
- Nutritional support for odontogenesis.
- Formation of tertiary dentine in response to trauma or stimuli
- Contribute towards the interstation pressure of dentinal fluid.
- Odontoblasts act as barrier which stops the spread of toxins to the pulp.
What is the composition of different dental tissues? (inorganic, organic, water)
a. enamel
b. dentine
c. cementum
d. alveolar bone
e. pulp
Enamel
- 96% inorganic
- 1% organic
- 3% water
Dentine
- 70% inorganic
- 20% organic
- 10% water
Cementum
- 65% inorganic
- 23% organic
- 12% water
Alveolar bond
- 60% inorganic
- 25% organic
- 15% water
Pulp
- 0% inorganic
- 25% organic
- 75% water
What are the layers of the pulp?
- Odontoblast layer at the periphery
- Cell-free zone of Weil (misonmer). This zone contains nervous plexus of Raschkow.
- Cell-rich zone
- Pulp core (nerves and blood vessels)
What are odontoblasts in the pulp linked by?
Ob are linked together by a number of small processes, tight junctions and desmosomes for communication and integrity.
Collagen fibres are released from OB process in form of microfilament.
What are the most dominant cells of the pulp?
Pulp fibroblasts which release collagen and other matrix proteins.
Fibroblasts are interlinked by desmosomes and gap junctions.
Apoptosis occur at the end life of fibroblasts.
What is the vascular supply of the pulp?
Through capillary plexus that do not enter dentinal tubules.
4-5% of capillaries are fenestrated to allow filtration.
High interstitial pressure does not allow leaking of fluids into the pulp which can be protective during progressing caries.
What is the pulp nervous supply?
Nervous venous plexus of Raschkow present just underneath coronal OB (not in the root).
Located in the cell-free zone of Weil.
Nerve fibres can extend between the OB and predentine to form marginal nerve plexus.
It can also extend into the dentine tubules.
Nerve fibres are more in the higher levels of the pulp, but they are less in the apical part.
70-80% of the nerve fibres are non-myelinated of C type.
90% of the myelinated fibres are of A delta type.
usually nerve fibres accompany blood capillaries.
What happen to the pulp as we age?
- Decrease in volume (deposition of more secondary dentine)
- Decrease in vascularity
- Decrease in sensitivity
- Decrease in ability of self repair (due to reduction of cells)
- Increase in fibrous tissue
- Increasing the resistance against injury
- Change in collagen fibres distribution
What are the different types of bone?
- Cancellous bone (also called spongey or trabecular bone)
- Cortical bone (also called compact bone)
Cancellous bone
Also known as spongy or trabecular bone, is lighter and less dense than cortical bone. It has a honeycomb-like structure of plates and rods that surround small cavities containing red bone marrow. Cancellous bone is found in the ends of long bones, as well as in the pelvic bones, ribs, skull, and vertebrae.
Cortical bone
Also known as compact bone, is dense and solid, and surrounds the marrow space. It’s found in the shafts of long bones and is responsible for the strength of those bones. Cortical bone has better structural support than cancellous bone, but fewer cells and slower revascularization.
What is woven bone?
Woven bone is a type of bone tissue that forms during fetal development and when bones are healing from a fracture:
Formation
Woven bone is produced when osteoblasts quickly create osteoid, an unmineralized extracellular matrix (ECM).
Structure
Woven bone has a random arrangement of collagen fibers, giving it a woven texture. It’s weaker and less rigid than lamellar bone, but the body can create it more quickly.
Replacement
In adults, woven bone is replaced by lamellar bone, which is stronger and more organized.
What is the cribriform plate and its function in a dental socket?
Cribriform plate is a thin layer (0.1-0.5mm) of compact bone that lines the socket to allow passing of blood vessels from PDL.
Alos passed sharpey fibres of PDL and in this case it is called bundle bone.
What is the function of the bone marrow?
Bone marrow is red at younger age and it possess a great haemopoietic capacity as it can produce; blood cells, osteoblasts, chondroblasts, myoblasts, fibroblasts and also contains adipose.
