key concepts of cavity design Flashcards
Why do we make holes?
To remove caries
To help make a restoration
Why isn’t it great to cut cavities?
Natural tooth tissue is finite Nothing can really replace it Rebuilding a tooth is complex and long It weakens the tooth Replacing a restoration enlarges the cavity
What is direct gold?
Thin gold foil is packed into the cavity
Doesn’t stick but interlocks
Lasts for decades
What is amalgam?
Doesn’t bond to tooth- fair marginal seal
Relatively rigid
Not antibacterial
Brittle
What is the caso-surface angle?
Angle between the restoration and the tooth
<90 degrees- enamel fractures off
>90 degrees- restoration fractures off
What three things are required for a restoration?
Marginal integrity
Resistance
Retention
What are some problems with burs?
Vibration can cause microscopic damage to hard tissues
Without adequate cooling, can overheat pulp
What is iatrogenic damage?
Adjacent teeth damaged
~plaque retentive factors so caries in future
What is glass ionomer cement?
Excellent bond to dentine and enamel
Mechanically weak- wear and fracture
What is atraumatic restorative treatment?
No electricity
No local anaesthetic
Remove caries and unsupported enamel w chisel
Place glass ionomer restoration
What is composite?
Excellent bond to enamel and dentine
Marginal seal and retention
Don’t need to cut retentive features
What is fissure sealant?
Prevent bacteria and substrates entering fissures
Reliant on bond with enamel
What are composites like now?
Outline dictated by ADJ spread
No minimum depth
Retention provided largely by adhesion
What do we currently think about unsupported enamel?
Less of a concern
Can support w glass ionomer
Bond w composite
Consider occlusal loading
What instruments do we currently use?
Small, round and pear shaped diamond bur
Round rose head slow handpiece bur
Air abrasion- no tactile feedback
Magnification
