CD4- Pulpal protection Flashcards
why is pulpal protection important?
Wish to maintain pulpal vitality
what is the formative function of the dental pulp?
produces the dentine that surrounds it
what is the nutritive function of the dental pulp?
Nourishes the avascular dentine. Non vital teeth are brittle.
what is the protective function of the dental pulp?
carries nerves that give dentine its sensitivity
what is the reparative function of the dental pulp?
produces new dentine in relation to physiological wear and unexpected insult such as caries
what do we want pulpal protection from?
- Chemical attack
- Thermal shock
- Galvanic effects
Name sources of chemical attack.
Constituents of certain restorative materials:
- Acrylic resin in some polymeric materials
- Acids in certain dentine bonding agents (if cavity is close to pulp)
- Residual acid from acidogenic bacteria
what can occur if acid is too close to the pulp?
- can inflate pulp
- increase in pressure in dental pulp
- entrance Is only tiny foramen so increased pressure can kill blood supply which can lead to an abscess
what insults the pulp?
cavity preparation - increased inflammatory cell activity in dental pulp as cutting generates heat
what minimises the heat in cavity preparations?
water coolant
what does cavity preparation result in?
a smear layer that occludes tubules
what are the smear layer constituents?
- bacteria from cavity
- collagen
- hydroxyl apatite
what effects can materials have if they enter the pulp through the tubules?
advantages- bonding
disadvantages- pulpal irritation
what is the ideal pulpal protector?
- Radiopaque ( white not translucent )
- Compatible with a wide range of restorative materials
- Obtundant
what is the meaning of obtundant?
calming, soothing effect on dental pulp
what is a coronal seal?
seal between restorative materials and tooth
what is a varnish? (no longer used)
polymer in volatile solvent
when is varnish applied and what effect does it have?
apply to cavity before placing amalgam:
- Solvent evaporates
- Residual polymer occludes dentinal tubules
- Dentinal fluid movement impaired
Describe the properties of calcium hydroxide (cavity bases).
- High pH gives beneficial irritancy
- High pH renders it bactericidal
- Thermal & electrical insulator
- Radiopaque
- Good restorative material compatibility
- Insufficient strength to withstand amalgam condensation/packing
- Not adhesive so no coronal seal
what is bactericidal?
bacteria die as they don’t like alkaline environment
Describe the properties of polycarboxylate cements e.g. Poly F (cavity bases).
- Acidic but high Molecular Weight (MW) reduces penetration and so mildly irritant to pulp
- Fluoride renders them bacteriostatic
- Thermal & electrical insulator
- Strength for amalgam condensation
- Restorative material compatibility is good
- Adhesive so coronal seal
- Not an obtundant
what is bacteriostatic?
inhibits bacterial growth
Describe the properties of reinforced zinc oxide eugenol e.g. kalzinol
- Beneficial irritancy
- Bactericidal due to Zinc
- Thermal & Electrical insulator
- Resin reinforcement withstands condensation
- Radiopaque due to Zinc
- Obtundant
- Incompatible with resin composites
- Non adhesive so no coronal seal
Describe the properties of zinc phosphate (cavity bases).
- Low pH and MW of parent acid render them highly irritant
- Thermal & electrical insulator
- Strength to withstand condensation
- Radiopaque
- Restorative material compatibility is good
- No obtundant effect
- Non adhesive so no coronal seal
Describe the properties of glass polyalkenoate’s either chemical or VLC e.g. vitrebond (cavity bases).
- High Molecular Weight parent acid renders them mildly irritant
- Bacteriostatic due to fluoride release
- Thermal & electrical insulator
- Strength to withstand restoration placement
- Adhesive
- Restorative materials compatibility is good
when is bonded restorations applied?
Applied to non adhesive restorations (Amalgam, Resin Composites) in conjunction with cavity base if necessary
what technique does resin composites used?
acid etch technique for enamel and dentine bonding agent
what is used for dental amalgam ?
use Vitrebond liner, Acid Etch, Scotchbond 1, Rely-x ARC in uncured state then pack amalgam.
what do these techniques do?
seal the cavity margins preventing ingress of fluids and bacteria and so protect the pulp
what is used when cavities are of ideal depth (2mm)?
no lining
what is used where cavities have a portion slightly deeper than the ideal?
- Dycal if to be restored with Glass polyalkenoate
- Dycal, followed by Acid Etch (30 Seconds) to enamel margins and Dentine Bonding Agent (Prime and Bond NT) if to be restored with Anterior Composite (Spectrum)
- Baseline/Vitrebond if to be restored with amalgam
what is used when cavity is grossly deep?
use Dycal and cover with a further layer of Vitrebond
Irrespective of cavity type, where should linings be placed?
NEVER extend them fully to the cavity periphery. It is ONLY the dentine overlying the pulp that is covered
