L9 Pulp Reaction to Restorative Procedures

Question 1

What features have been measured in research to histologically assess the composition of pulp beneath cavities?

Answer 1

• Reduction in odontoblast number
• Displacement of odontoblast nuclei
• Inflammatory cells in parts of pulp normally occupied by odontoblasts
• Inflammation elsewhere in the pulp
• Reparative dentine formation betneath the cavity
• Distance of inflammation from cavity floor (mm)

Question 2

What are the effects of cutting a tooth?

Answer 2

Creates heat and pressure, and desiccates (dries) the tooth.

Question 3

What factors influence the degree or likelihood of pulp injury during the cutting process?

Answer 3

• Residual dentine thickness
• State of pulp prior to treatment e.g. pre-existing inflammation
• Quality of dentine e.g. reactionary
• Mass of material
• Area of cavity floor (no. of tubules occluded)

Question 4

When does reparative dentine production begin after cavity preparation?

Answer 4

Approx. 20 days after cavity prep.

After 100 days 0.1mm will be deposited.

Question 5

Why are most materials most likely to be irritants when first placed?

Answer 5

Because when they are first placed they have not yet fully polymerised and most of the irritant constituents are only partially reacted, so are free to cause tissue damage.

Question 6

How can toxic constituents be released from an already set material?

Answer 6

• By corrosion
• By abrasion
• By leaching (if soluble) e.g. fluoride leaching from GIC

Question 7

Which materials were found to have the most and least effect on fibroblasts in vitro?

Answer 7

• Amalgam was the least toxic

- Zinc eugenol was the most toxic

Question 8

What is a key factor that contributes to pulp damage in restorative procedures and how can it be overcome?

Answer 8

Bacterial microleakage
- A base must be used to prevent microleakage between material and tooth tissue
- E.g. Kalzinol (zinc oxide eugenol cement)
- Bacterial infection is more important than the restorative material of choice itself
- More likely to be penetration from the tooth surface than proliferation of
bacteria trapped in the cavity at the time of restoration
- Extent of bacterial microleakage seems to be the most important factor
determining the extent of the inflammatory changes in the pulp beneath cavities