Cavity Preparation Flashcards
What determines cavity design?
Extent and position of caries.
Choice of restorative material.
Structure and properties of the dental tissues.
In what situations is it likely that you will need to provide a restoration?
Caries has caused a cavitation.
Patient cannot cleanse the lesion.
Lesion is into dentine radiographically.
Lesion is causing a pulpit’s.
Lesion is anaesthetics.
Why does anything that happens in dentine affect the pulp?
Odontoblast processes from the odontoblasts in the pulp extend into the dentinal tubules.
Nerve supply as well.
Define enamel prism structure orientation of a proximal but cavity prep?
Gingival floor- end cut prisms
Buccal or lingual axial walls- side cut prisms.
Why is tertiary dentine not good to bond to?
Very irrigerar structure- it is hard to bond to.
What are the principles of cavity design and preparation?
Remove carious enamel.
Identify extent of caries at the ADJ and smooth enamel margins.
Remove caries dentine- peripherally first and then circumferentially deeper.
Only remove deep caries over the pulp.
Outline form modification
- Enamel finishing
- Occlusion
Requirements of the restorative material.
Internal design modification
- no sharp internal line or point angles.
Requirements of the restorative materials.
What can be used to remove carious dentine?
Excavator
Slow speed round bur
Chemo-mechanical caries removal
Caries detector dyes
What instrument should be used when removing carious dentine overlying the pulp?
Largest instrument
- large round slow speed
Large excavator
Chemo-mechanical caries removal.
For amalgam, what cavity design principles are applied?
Internal dimensions of the cavity need to be greater than the access to it.
CSMA must be 90 degrees.
For composite, what cavity design principles are applied?
CSMA larger than in amalgam to increase bonding area and ensure no unsupported enamel- create a bevel.
No undercuts necessary.
Why must you place a bevel for composite application?
Aligns orientation of the prisms for composite.
- so that the prisms are end cut instead of side cut.
Why should caries not be left at the ADJ?
Results in unsupported enamel and early breakdown of the restoration margin if micro leakage occurs.
What is configuration factor?
Ratio of bonded to unboned surfaces.
Why is a high configuration factor undesirable?
Increases polymerisation contraction stress.
