Dental Materials: Linings Flashcards
What are the advantages of using an intermediate restorative material (lining)?
Prevents gaps therefore prevents fluids and bacteria/endotoxins entering the tooth tissue
Acts as a protective barrier:
Protects pulp from chemical stimuli from unreacted chemicals in materials or the pH of fillings.
Acts as a protective barrier against thermal stimuli: Protects against exothermic setting and heat conduction via filling material.
Calms inflammation and promotes healing of the pulp.
Reduces patient symptoms (pain) before definitive restoration placed.
What is the difference between a base and a lining?
a cavity base is a thick bulk used to block out undercuts.
A cavity lining is a thin coating that is placed over EXPOSED dentine to seal the tubules.
List the ideal properties of a lining material. (9)
Ease of use:
Long working time and short setting time. (command set ideally)
Thermal properties:
Low conductivity. Similar expansion coefficient and thermal diffusivity to dentine.
Mechanical properties:
High compressive strength- prevent breakage during filling placement - and similar modulus to dentine.
Radiopaque:
Difference between lining and tooth on radiograph.
Marginal seal:
Permanent and impenetrable chemical bond to dentine.
Solubility = LOW
Cariostatic:
Releases fluoride.
Antibacterial properties.
Prevents secondary caries.
Biocompatible:
Non-toxic and is not damaging to the pulp. (Neutral pH and no exothermic heat from setting) Has low thermal conductivity.
Compatible with restoration materials.
What kind of reaction takes place in a setting calcium hydroxide liner?
Chelation reaction.
What is the pH of calcium hydroxide cement used as a liner?
12
What are the advantages of using a strong alkaline liner?
Microorganisms in the tooth prefer acidic conditions- therefore the alkaline liner kills them off.
Strong alkaline environments irritate the pulp and cause it to lay down tertiary dentine = thicker dentine layer.
