DEH 103: Histology & Embryology
Chapters 9 & 10: Dental Pulp and Cementum
Chapters 9 & 10: Dental Pulp and Cementum
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Cartes-fiches
What cells form the pulp?
Cells of the dental papilla of the embryo
What are the 2 divisions of pulp in a tooth?
- Coronal pulp: in the crown larger portion than root. Has 6 surfaces (M, D, B, L, O, floor). Pulp horns extend into the cusps of the teeth.
- Radicular pulp: in the roots. Has an opening through the cementum into the surrounding PDL
The apical foramen is the opening in the cementum in which the pulp extends into the PDL. How wide is this hole.
0.3 - 0.6 mm
What is the intercellular matrix of pulp composed of?
- Veins
- Arteris
- Nerves
- Fibroblasts
- Collagen fibers
What is the histology of young pulp?
- Fibroblasts: most numerous cell. Star shaped and responsible for formation of collagen fibers and ground substance of the pulp
- Histocytes & undifferentiated mesencyhmal cells: defense mechanism
- Odontoblasts: specialized dentin tissue cells
What are teh 4 zones of the pulp?
- Odontoblastic zone (odontogenic zone)
- Cell-free zone
- Cell-rich zone
- Pulpal core
This is the 1st zone of pulp that is closest to the dentin. It lines the outer pulpal wall and consists of bodies of the odotoblastic process located in the dentinal tubules in the adjacent tooth. Odontoblasts are capeable of forming secondary and tertiary dentin.
Odontoblastic zone (odontogenic zone)
What are the 3 types of junctions that can be found in the odontoblastic zone?
- Tight: maintaines relationship between cells. Prevents pulp leakage into dentin
- Gap: openings between odontoblasts for communication
- Intermediate: combination of the above 2
This zone is nearest to the odontoblastic layer inward from the dentin. This zone consists of fewer cells than the next zone up. Nerve and capillary plexus are located here.
Cell-free zone
This is the next layer located next to the cell free zone. It is rich in cells and contains extensive vascular and neural systems.
Cell-rich zone
This is the core of the pulp. It is the innermost zone and has very extensive vascular and neural supply.
Pulpal core
What are 3 types of nerve cells?
- Schwan cells: line the myelin sheath
- Endothelial cells: line capillaries, veins, and arteries
- Pericytes and undifferentiated cells: called into action when odontoblast or fibroblasts are needed.
What are 3 theories of pain reception?
- Direct innervation theory: nerves extend to DEJ
- Transduction theroy: odontoblasts process is the receptors
- Hydrodynamic theroy: dentinal tubules contain fluid that fluctuate to the pulp chamber and transmit impulses
True/False:
Blood pressure and flow is more rapid the the pulp than any other part of the body.
True
What are the 5 functions of the pulp?
- Inductive
- Formative: produce collagen fibers and the groud substance of dentin
- Protective: resonse to stimuli.
- Nutritive: recieve nutrients from the bloodstream
- Reparative: sclerotic or 2nd dentin formation
These are mineralized bodies, irregular and round shaped requenly found in the pulp of teeth that have experienced trauma.
Pulp sntes (denticles)
What does aging pulp look like?
- Pulp horns receded
- Increase in colalgen and decrease in intracellular substance
- Smaller pulp cavity r/t secondary tertiary dentin
What are the 2 major functions of cementum?
- Attach the teeth to bone
- Anchor the PDL
Where is the cementum the thickest / thinnest?
- Thickest: apex
- Thinnest: cej
What are the functions of cementum?
- Tooth attachment medium (primary function)
- Protect the root dentin
- Serves as the mending tissue in a fracture site
- Compensate for the loss of occlusal tooth tissue
What are the 3 relationships between the CEJ and Enamel?
- Overlap: 60-65%
- Meet: 30%
- Gap: 5-10%
What are 3 types of cementicles?
- Free cementicles: in the PDL
- Attached cementicles: attached to the surface
- Interstitial cementicles: embedded into the cementum
What are 2 major functions of cementum?
- Attach teeth to bone
- Anchor the PDL
Is cementum a renewable source? Where are the cells?
- Yes
- in the PDL
Does cementum contain nerves or blood supply?
No -- avascular and aneural
Where is cementum the thickest and where is it cellular and/or acellular?
- Root apex (cellular)
- CEJ (acellular)
Name 5 reasons for bone resorption.
- Mesial drift
- Orthodontics
- Tooth eruption
- Periodontal disease
- Malocclusion trauma
What is the 1st layer of cementum desposited and what is it also known as?
- Cementoid
- Intermediate cementum
What does the appositional growht of cementum result in?
Incremental lines
After trauma or tooth movement what happens to cementum?
Resorption and reversal line formation
What attachment is imbedded into bone and cementum to help anchor the tooth?
Sharpey's fibers
Name the term for excess cementum at the root apex?
Hyercementosis (cemtnum hyperplasia)
What is teh name of groups of epithelial cells that get located near cementum in the PDL during root formation after Hertwigs sheath disintegrates?
Rests of Mlassez
What is the most abundant cell in the PDL and what do they form?
Fibroblasts and collagen fibers
What is located between bundles of principle fibers of the PDL -- where nerves, lymphatic's, and blood supply are carried?
Interstitial space
Name 2 of 3 blood vessles that run through the PDL?
- Posterior alveolar arteris
- Inferior alveolar arteries
- Facial artery
What nerve supplies the maxillary and mandibular arches? Name each division.
- 2nd division of the trigeminal nerve (maixllary)
- 3rd division of the trigeminal nerve (mandible)
What are the classificaion groups for fibers for the PDL and how many are in each of these groups?
- Dentoalverolar (5)
- Gingival (4)
What are the 4 main functions of the PDL?
- Supportive
- Sensory
- Nutritive
- Formative
What is the compact bone that supports the tooth in the socket? What is it called in radiographs?
- Alveolar process (bundle bone)
- Lamina dura
