CD4- Pulpal protection

Question 1

why is pulpal protection important?

Answer 1

Wish to maintain pulpal vitality

Question 2

what is the formative function of the dental pulp?

Answer 2

produces the dentine that surrounds it

Question 3

what is the nutritive function of the dental pulp?

Answer 3

Nourishes the avascular dentine. Non vital teeth are brittle.

Question 4

what is the protective function of the dental pulp?

Answer 4

carries nerves that give dentine its sensitivity

Question 5

what is the reparative function of the dental pulp?

Answer 5

produces new dentine in relation to physiological wear and unexpected insult such as caries

Question 6

what do we want pulpal protection from?

Answer 6

• Chemical attack
• Thermal shock
• Galvanic effects

Question 7

Name sources of chemical attack.

Answer 7

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

Question 8

what can occur if acid is too close to the pulp?

Answer 8

• 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

Question 9

what insults the pulp?

Answer 9

cavity preparation - increased inflammatory cell activity in dental pulp as cutting generates heat

Question 10

what minimises the heat in cavity preparations?

Answer 10

water coolant

Question 11

what does cavity preparation result in?

Answer 11

a smear layer that occludes tubules

Question 12

what are the smear layer constituents?

Answer 12

• bacteria from cavity
• collagen
• hydroxyl apatite

Question 13

what effects can materials have if they enter the pulp through the tubules?

Answer 13

advantages- bonding

disadvantages- pulpal irritation

Question 14

what is the ideal pulpal protector?

Answer 14

• Radiopaque ( white not translucent )
• Compatible with a wide range of restorative materials
• Obtundant

Question 15

what is the meaning of obtundant?

Answer 15

calming, soothing effect on dental pulp

Question 16

what is a coronal seal?

Answer 16

seal between restorative materials and tooth

Question 17

what is a varnish? (no longer used)

Answer 17

polymer in volatile solvent

Question 18

when is varnish applied and what effect does it have?

Answer 18

apply to cavity before placing amalgam:

• Solvent evaporates
• Residual polymer occludes dentinal tubules
• Dentinal fluid movement impaired

Question 19

Describe the properties of calcium hydroxide (cavity bases).

Answer 19

• 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

Question 20

what is bactericidal?

Answer 20

bacteria die as they don’t like alkaline environment

Question 21

Describe the properties of polycarboxylate cements e.g. Poly F (cavity bases).

Answer 21

• 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

Question 22

what is bacteriostatic?

Answer 22

inhibits bacterial growth

Question 23

Describe the properties of reinforced zinc oxide eugenol e.g. kalzinol

Answer 23

• 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

Question 24

Describe the properties of zinc phosphate (cavity bases).

Answer 24

• 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

Question 25

Describe the properties of glass polyalkenoate’s either chemical or VLC e.g. vitrebond (cavity bases).

Answer 25

• 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

Question 26

when is bonded restorations applied?

Answer 26

Applied to non adhesive restorations (Amalgam, Resin Composites) in conjunction with cavity base if necessary

Question 27

what technique does resin composites used?

Answer 27

acid etch technique for enamel and dentine bonding agent

Question 28

what is used for dental amalgam ?

Answer 28

use Vitrebond liner, Acid Etch, Scotchbond 1, Rely-x ARC in uncured state then pack amalgam.

Question 29

what do these techniques do?

Answer 29

seal the cavity margins preventing ingress of fluids and bacteria and so protect the pulp

Question 30

what is used when cavities are of ideal depth (2mm)?

Answer 30

no lining

Question 31

what is used where cavities have a portion slightly deeper than the ideal?

Answer 31

• 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

Question 32

what is used when cavity is grossly deep?

Answer 32

use Dycal and cover with a further layer of Vitrebond

Question 33

Irrespective of cavity type, where should linings be placed?

Answer 33

NEVER extend them fully to the cavity periphery. It is ONLY the dentine overlying the pulp that is covered