Restorative Flashcards
How do you prep a cavity?
- Identify carious enamel- remove to show maximal extent at ACJ and smooth
- Remove carious dentine from ACJ then circumferentially deeper
- Remove deep caries over pulp
- Outline form- no unsupported enamel, suitable for occlusion and restorative material
- Internal design mod- no sharp line or point angles
Give advantages of composite
Better aesthetics
Bonds to tooth
Minimal prep required
On demand set
Low thermal conductivity
Supports remaining. Tooth structure
Give disadvantages of composite
Under polymerised base- place <2mm increments
Polymerisation shrinkage
Moisture sensitive
Post -op sensitivity due to etch
Longer placement time
Less wear resistance
Shorter lifespan.
What is the failure rate of composite?
Depends on OH/diet and placement
Should last 5-10 years
13.7% failure rate at 8 years
What are the constituents of composite?
Glass filler particles
Monomer- BIS GMA
Photoinitiator
Low weight dimethacylate
Silane coupling agent
What are the cavity requirements for a composite restoration?
No undercuts required
Smooth margins
No unsupported enamel
No sharp line angles
Bevelled cave-surface margin angle- increase bonding area
Why would you place flowable composite at the base of a cavity?
Reduce contraction stress
Achieve optimal adaption in non-load bearing area
Give a reason for using warm composite
Mediates contraction stress
Give methods of avoiding sensitivity following composite placement
Reduce polymerisation contraction stress (small increments, reduce configuration factor by placing comp on few surfaces as possible)
Place a liner
Check occlusion after restoring
What are the functions of etch on dentine?
Opens tubules
Removes smear layer
Decalcifies dentine
What are the functions of DBA on dentine?
Primer- bonds to dentine with hydrophilic ends and hydrophobic ends are exposed
Adhesive- penetrates primed surface by molecular entanglement binding to primer by hydrophobic interactions
What are the benefits of etching enamel?
Increases surface energy
Removes contaminants
Increases surface area by roughening allowing micro mechanical interlocking with resin.
Give advantages of amalgam
Durable
Short placement time
Radiopaque
Colour contrast
Self-hardens at mouth temp
Resistance to surface corrosion
Good wear resistance
Good bulk strength
Give disadvantages of amalgam
Potential mercury toxicity
Poor aesthetic
Doesn’t bond to tooth
High thermal diffusivity
Requires removal of sound tissue during cavity prep
Lichenoid reactions- T4 hypersensitivity
Tooth discolouration
Amalgam tattoos
Creep/marginal breakdown
What is the failure rate of amalgam?
Can last up to 20 years
5.8% failure rate at 8 years
Give cavity requirements for amalgam
Undercuts required
CSMA 90degrees for butt joint finish
Add grooves, isthmus, dove tails for retention
Must be at least 2mm deep
No unsupported enamel
What are the functions of dental dam?
eliminate bacterial contamination
Prevent inhalation of instruments
Retract/protect soft tissue
Reduced chair side time
Increased operator and patient confidence
Moisture control
