care of the dental pulp Flashcards
where are odontoblasts found at the pulp and what do they produce? what is there function?
odontoblasts are found at the edge of the pulp and they produce dentine and there function function is to produce dentine, regular secondary dentine and irregular (reparative) dentine protecting the pulp.
what are effects of cavity preparation that could occur?
reversible pulpits symptoms – pain (doesn’t linger when stimulus removed), pain which is difficult to localise, normal radiographic appearance, not Tender To Percussion (TTP).
irreversible pulpits-pain - spontaneous or reaction to stimulus, lasts, widened perio lig may be seen radiographically.
what is the dentine smear layer? what is it composed of?
When dentine is cut with a bur during cavity prep
a smear layer is left on the dentine surface.of
Cut tooth debris
Plaque
Bacteria
Pellicle
Saliva
Blood
why is the smear layer so important to remove?
It should be removed so that resin materials can penetrate the tubules and create a protective seal
It interferes with the bond between dentine and the filling material
It adheres to dentine and occludes dentinal tubules
A good seal helps eliminate bacterial leakage and post operative sensitivity
How is the smear layer removed?
It is removed with 37% Phosphoric acid for 10 seconds in dentine, 20 seconds in enamel
Then rinsed with water
This dissolves mineral from the surface
Creates a porous surface
Exposes collagen fibrils of the dentine matrix
what happens after the removal of the smear layer?
Creates a porous surface.
Exposes collagen fibrils of the dentine matrix.
After rinsing, slightly dry 10 for seconds
Moisture keeps the fibrils fluffed up, ready to bond.
Over-drying causes collagen fibrils to collapse, occlude tubules and block penetration of bond
what else can remove the smear layer?
Cavity conditioner 20% polyacrylic acid
what is the hybrid layer during bonding?
dentine bonding agents’ are applied to the moist layer.
Penetrates through the water and between the fibrils, into tubules.
(air drying is then carried out to remove volatile agents)
The layer of resin + collagen fibrils is
the hybrid layer.
why seal dentinal tubules?
microleakage Restorations that do not completely seal at the margins.
Leakage occurs at the microscopic level.
Contributes to caries under restorations and sensitivity.
Contaminants are substances that interfere with enamel or dentine bonding.
what is contamination caused by when bonding?
Caused by microleakage.
Due to poor bonding.
Consists of bacteria, blood or saliva.
Failure in bonding procedure and technique.
But also
Eugenol in temporary dressing materials.
what is calcium hydroxide used for? and what does it stimulate?
Direct and Indirect pulp capping
Protective liner under restorative materials
Stimulates the formation of secondary dentine
what is pulp capping?
a technique to protect the pulp after it has been exposed or nearly exposed
what is direct pulp capping?
indicated when pinpoint exposure occurs in adult tooth with no symptoms.
what is indirect pulp capping?
Demineralised but non-infected dentine is left at the base of the cavity - stained but firm dentine in a cavity which is symptomless and vital.
Avoids exposure.
Stepwise technique is where indirect pulp cap is covered with dressing and left for a few months for dentine to form, then dressing is removed, and filling placed
