Transcript
Tooth Pulp
Oral PhysiologyDr. Maria Eller Isabel T. Collantes
Parts of the tooth
Enamel Dentine Pulp
Periodontal Tissue
Gingivae Alveolar Bone Cementum Periodontal Ligament
Enamel
Outer most layer of the crown
The hardest tissue in the body
DENTIN
The second layer of the crown
Generally light yellow in colour
Its colour determines the overall colour of the tooth
There are many microscopic tubules inside the dentine which connect to the pulp.
Dentin
Pulp
Fluid Nerve Fibers
Odontoblast Cell
Periodontal tissues
Gingiva
Alveolar bone
Cementum
Periodontal Ligament
GINGIVA
The fibrous investing tissue covered by
keratinized epithelium The gingiva is one of
the soft tissues that line the oral cavity
All the soft tissue in the mouth are Known
as the oral mucosa
Gingiva
ALVEOLAR BONE
Also called the “alveolar process”
the thickened ridge of bone containing the tooth sockets in the mandible and maxilla.
Alveolar bone
PERIODONTAL LIGAMENT
Connects the cementum of the tooth root to the alveolar bone of the socket.
Periodontal Ligament
CEMENTUM
Bonelike rigid connective tissue
covering the root of a tooth from the cementoenamel junction to the apex and lining the apex of the root canal
It also serves as an attachment structure for the periodontal ligament, thus assisting in tooth support. Cementum
• Formation of dentine (dentinogenesis)• Sensation (pain only?)• First line of defense to injuries and infection
of dentin• Tertiary dentin• Immuno-competent• Clearance of toxic substances
Functions of dental pulp
PULP
Innermost part of the tooth
Highly vascular and richly-innervated connective tissue forming the soft core of the tooth
Pulp
Consist of fibers (collagen), cells (odontoblasts, fibroblasts, undifferentiated mesenchymal cells), and a matrix (proteoglycans and fibronectin)
Encapsulated and protected by hard tissue walls
Very low compliance because the surrounding dentin prevents any significant volume changes if the pressure within the pulp chamber changes
Pulp
Contains large number of free nerve endings
Afferent neurons originating from the maxillary or mandibular division of the trigeminal nerve
Pulp
four distinct zones 1. odontoblastic zone
at the periphery 2. cell-free zone of
Weil – below the ODs 3. cell-rich zone 4. pulp core – major
vessels and nerves
Predentin
Odontoblasts
Cell-free zone
Cell-rich zone
Cell bodies
Odontoblasticprocess
Dentin
Predentin
Odontoblasts layer
Cell free zone
Cell rich zonePulp core
Odontoblastic layer
Lines the outer pulpal wall and consists of the cell bodies of odontoblast
Secondary dentin may form in this area from the apposition of odontoblast.
Cell Free zone
Fewer cells than odontoblastic layer Nerve and Capillary plexus is located
here
Cell Rich Zone
Increased density of as compared to cell free zone
More extensive vascular system
Pulpal core
Center of the pulp chamber Many cells Extensive vascular supply Similar to cell rich zone
Cells in the pulp
odontoblast Fibroblast Mesenchymal cells Macrophages Lymphocytes Dendritic cells
Pulp
Odontoblasts line the periphery of the pulp
chamber columnar in the crown region
of the fully developed tooth more cuboidal at the midpoint
of the pulp chamber the morphology reflects their
activity – the more active the more elongated they are – with more cytoplasm
Odontoblast
active ODs within the pulp have prominent organelles with multiple vesicles
CN pathway is similar to that of the pulp fibroblasts
CNs and non-CN proteins are packaged into secretory granules for exocytosis
the non-CN proteins are the same as those found in the dentin
Fibroblasts
greatest number numerous in the coronal
portion of the pulp form the cell-rich zone form and maintain the pulp
matrix – CN fibers and ground substance
in young pulp the fibroblasts are active and have extensive cytoplasm and organelles
decrease in size with age and they flatten
Mesenchymal cells
undifferentiated cells of the pulp
from neural crest (ectodermal)
depending on the stimulus – give rise to the ODs or fibroblasts of the pulp
Vascularity and Nerves of the Vascularity and Nerves of the PulpPulp
The pulp organ is extensively vascular with
vessels arising from the external carotids to the
superior or inferior alveolar arteries. It drain by
the same vein.
Blood flow is more rapid in the pulp than in
most area of the body, and the blood pressure
is quite high
The walls of the pulpal vessels become
very thin as their enter the pulp.
Nerves : Several large nerves enter the
apical canal of each Molar and Premolar
and single ones enter the anterior teeth.
This trunks transverse the radicular pulp,
proceed to the coronal area and branch
peripherally.
Nerves and Vessels of the pulp
• Blood and vessels enter and exit
the dental pulp by way of the
apical and accessory foramina
• Pulp is richly innervated;
nerves enter the pulp through
the apical foramen, along with
afferent blood vessels and
together form the neuro-
vascular bundle
Nerves in pulpNerves in pulp
Dental PulpDental Pulp
Nerve Blood vessel
Subodontoblastic zone – is a major site of nutrient and gas exchange within the subodontoblastic plexus
In a healthy tooth pulp, blood occupies about 5% of the total volume
High blood flow comparable to the brain and liver
Blood flow is controlled by autonomic nervous system primarily by sympathetic efferent nerve fibres
Activity in nociceptive afferents can also influence pulpal blood flow by the release of vasodilatatory substances
Extravasation – it is a leakage of plasma proteins from venules to the insterstitial space and that will be an inflammation, thus increases intrapulpal pressure
Inflammation of the pulp is induced by bacterial or mechanical trauma and can lead to increases in pressure in the pulp chamber
Increased pressure will lead to tissue hypoxia then necrosis
Types and properties of pulpal sensory nerve fibers
A – beta fibers A – delta fibers C – fibers Non – myelinated sympathetic fibers
A-beta fibers
Conduction velocity 30-70 m/sVery low threshold, non-
noxious sensation50% of myelinated fibers in pulpFunctions not fully known
A – delta fibers
Conduction velocity 2-30 m/s Lower threshold Involved in fast, sharp pain Stimulated by hydrodynamic stimuli Sensitive to ischemia Sharp pain
C - fibers
Conduction velocity 0-2 m/s Higher threshold Involved in slow, dull pain Stimulated by direct pulp damage Sensitive to anesthetics Dull pain
Non – myelinated sympathetic fibers
Conduction velocity 0-2 m/sPost-ganglionic fibers of
superior cervical ganglionVasoconstriction
Possible mechanisms of dentine sensitivity
Hydrodynamic mechanism(Gysi, 1900; Brannstrom, 1963)
Neural Theory
Attributes activation to excitation of the nerve endings within the dentinal tubules, leading to action potentials that are conducted along the parent primary afferent nerve fibres in the pulp into the dental nerve branches and then to the brain
Odontoblastic transduction theory
Proposes that the stimuli initially excite the odontoblast process or body, the membrane of which may come into close apposition with that of the nerve endings in the pulp or in the dentinal tubule
The odontoblast then transmits the excitation to the associated nerve endings
However, lack of evidence for either synapses or neurotransmission between odontoblast and dentinal nerve opposes this theory
Hydrodynamic theory
Proposes that the stimuli cause displacement of the fluid within the dentinal tubules
Stimuli such as drilling of dentin, probing, and air drying of exposed dentin, mechanical irritation of pulp, and application of hyperosmotic solutions promote liquid displacement within the dentinal tubules
Displacement occurs in either an outward or an inward direction
Activate mechanoreceptors in the nerve endings in the dentin or pulp
Clinical correlatesTOOTHACHE
It is a clinical manifestation of tooth pulp physiology
Perceived only a limited number of forms Intensity very close to the threshold of pain
can induce a non painful sensation called “pre pain”
Pre pain or paraesthesia may be due to recruitment of a few nociceptive afferent fibres, but not enough to give the pain sensation
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