protecting the pulp Flashcards
Sources of chemical attack?
acrylic resin
acids in bonding agents
residual acid from acidogenic bacteria
sources of thermal shock?
polymerisation exotherm of some restorative materials
light curing units
food and drinks
cavity prep
galvanic shock?
restorations of dissimilar metals in close proximity
What is the smear layer?
result of prep
occludes dentinal tubules with bacteria, collagen, hydroxyapitite
Properties of calcium hydroxide?
high PH- initially irritant- reactionary dentine high PH- bacteriocidal thermal/ electrical insulator radiopaque compatible with restorative materials Not adhesive- no coronal seal insufficient strength for condensation
Properties of zinc polycarboxylate cements
Poly F
high molecular weight reduces penetrations to tubules contains fluoride + zinc- bacteriostatic good strength for restoration placement insulates good compatibility
properties of zinc oxide and euganol
Kalzinol, sedanol
slightly irritant- reactionary dentine bacteriocidal- zinc insulates obtundant- euganol not adhesive- no coronal seal not compatible with resin composite
Properties of zinc phosphate
rarely used due to highly irritant
properties of glass polyalkenoates
baseline, vitrebond
mildy irriatant- reactionary dentine bacteriostatic- fluoride insulator sufficient strength coronal seal good compatibility
when to line?
when cavity extends more than 2mm
when cavities is within 2 mm of pulp
where do you place linings?
pulp- axial wall and/or occlusal floor
what effect may lining the base of a cavity have?
weaken overlying filling material
When will a patient experience discomfort?
when caries reaches within 0.5mm of pulp
when is an indirect pulp cap used?
when cavity extends to within 0.5mm of pulp
what material is used for indirect pulp cap?
hard setting calcium hydroxide to the deepest part of the cavity
can be covered in resin modified GI
when is a direct pulp cap used?
when pulp is exposed
What materials are used for direct pulp caps?
calcium hydroxide- hard setting
mineral trioxide aggregate- MTA
what it the criteria for direct pulp capping?
tooth is vital
no hx of pain
pulp must be pink and healthy with no excessive bleeding
What is the technique for direct pulp capping?
dry tooth with cotton wool- NO AIR
apply material to exposure
resin modified GI may be applied on top
restore as normal
When is step wise excavation used?
when trying to avoid exposing pulp
what can be left in cavity re. step wise excavation?
stained soft dentine
what must be clear re. step wise?
ADJ
what is the technique used re. stepwise?
seal entire base of cavity where caries remains with calcium hydroxide
Dress with GI
Remove GI and lining 6-12 months later
How should base of lining be after 6-12 months
still stained, but firm
