Pulp Therapy/Orofacial Trauma Flashcards
(184 cards)
Dentin-Pulp Complex
- Pulp originates from mesenchymal tissue
- Odontoblasts synthesize dentin organic matrix and line the edge of the pulp space
- Cytoplasmic processes extend into dentin tubules
- Orbans (1980) stated that “The pulp lives for the dentin and the dentin lives by the grace of the pulp.”
Dentin components
- Inorganic - hydroxyapatite
- Organic - mostly type I collagen but odontoblasts also secrete type V collagen, dentin sialoprotein and phosphophoryn, acid phosphatase and alkaline phosphatase
Dentin types
- Primary - tubular dentin formed before eruption; includes mantle dentin
- Secondary - regular, circumferential dentin formed after tooth eruption; tubules are continuous with primary dentin
- Tertiary - in response to irritation
Primary dentin vs secondary dentin
- Bulk of dentin formed during primary dentinogenesis
* Secondary dentin forms at a slower rate over the life of the tooth
Tertiary dentin
• Forms in response to irritation:
- Previously called irregular, irritation, reparative and/or replacement dentin
- Reactionary dentin - formed by original odontoblasts; continuous with secondary dentin
- Reparative dentin - original odontoblasts died, dentin formed by new odontoblast-like cells; not continuous with secondary dentin
Dentin-pulp reaction to damage
• When there is damage to dentin-pulp complex due to disease, trauma, operative, odontoblasts react to defend the pulp • Stimulated to create tertiary dentin - Appears sclerotic histologically - Decreased dentin permeability - Depends on extent of injury
Mild insult consequence
Odontoblasts usually survive and secrete reactionary dentin in response to injury
Severe insult consequence
May cause death of odontoblasts
- May lead to generation of new odontoblast-like cells and secretion of reparative dentin matrix
• Tubular structure discontinuity and reduced permeability
Molecular basis for odontoblast stimulation
- TGF-b (transforming growth factor beta) is sequestered in dentin matrix during tooth development
- TGF-b may be released when caries or acid etchant causes dissolution of matrix
- Growth factors interact with pulp to cause proliferation and differentiation of mesenchymal cells to form reparative dentin
Odontoblast stimulation by calcium hydroxide
Calcium hydroxide has a similar effect – high pH causes slight demineralization and releases TGF-b leading to reparative dentin and apexification
Example of mild insult
- Cavity preparation (no pulp exposure)
* Caries lesion in dentin
Example of severe insult
- Chronic pulpal inflammation due to deep caries
- Dry cutting
- Endotoxins from bacteria in deep caries lesions
- Mechanical exposure of pulp
- Presence of bacteria increases extent of pulpal inflammation
Importance of seal on restorations
• Importance of a good seal on restorations to minimize microleakage and bacterial invasion
What is RDT?
Remaining dentin thickness
Values for remaining dentin thickness
- Bacteria in cavities with RDT < 0.25 mm results in more severe pulp inflammation than when RDT is greater
- Best to have > 0.50 mm
- When RDT is > 0.5 mm diffusion of irritants is delayed – odontoblasts secrete reactionary dentin - increases distance between pulp and restorative material
- When RDT is < 0.5 mm, reduction in odontoblasts – differentiation of odontoblast-like cells - secretion of reparative dentin - decreased permeability - protective barrier
Pulp cells
• Fibroblasts are most frequent cell type
- Capable of generating odontoblast-like cells
- Many are undifferentiated (stem cells)
• Macrophages - involved in signaling pathways, activated by inflammation
• Dendritic cells - induce T-cell dependent immunity
• T-lymphocyte
• Mast cells - rare in normal pulp, common in chronically inflamed pulp
Structural proteins of pulp
• Collagen - type I and III are main subtypes
- Comprises 26-32% of dry weight in premolars and molars
• Elastin - found in walls of arterioles
Cells in dental pulp
- Fibroblasts
- Odontoblasts
- Histiocytes
- Macrophages
- Granulocytes
- Mast cells
- Plasma cells
Neuropeptides
• Calcitonin gene-related peptide (CGRP) is most common
- Important in induction of neurogenic inflammation
• Substance P
• Neuropeptide Y
• Neurokinin A
• Vasoactive intestinal peptide (VIP)
Drug to regrow teeth?
• Tideglusib stimulates stem cells in the pulp of teeth.
• Functions as a Gycogen Synthase Kinase (GSK-3) enzyme antagonist
- GSK-3 is involved in dentin degradation
• From the lab of Paul Sharpe in the UK
Types of pain
• Spontaneous, nocturnal, constant
- Irreversible
• Thermal, chemical, intermittent
- Reversible
Subjective findings
- Young children are not good historians
- May not report pain
- May report pain when no evidence of disease
Objective findings
- Extraoral
- Intraoral
- Radiographically
- Percussion
- Palpating
- Cold testing
Nerve fibers in pulp
• Myelinated — A fibers
- A-beta and A-delta (90%) both innervate dentinal tubules and are stimulated by fluid movement in the tubules
- Increase in number over time; relatively few at time of eruption - may be why EPT is unreliable in young teeth
• Unmyelinated — C-fibers
- 3 to 8 times more frequent than A-delta fibers in pulp