Amalgam Flashcards
Advantages
durable good long term clincal performance long lasting long term resistance to surface corrosion radiopaque ecomnomical shorter placement time less moisture and tech sensitive
Disadvatanges of amalgam
Poor aesthetics does not bond easily to tooth substance thermal diffusivity high marginal breakdown cavity prep may result in destruction of sound tooth tisuse amalgam tattoo tooth discolouration mercury toxicity lichenoid reactions
Cavo surface angle
90-120 degrees
Why does dithcing occur in an amalgam
Material is repedetly stressed for long periods of time at low stress levels, below elastic limit
This may result in permanenet deformation
Amaglam sits proud of sruface due to flow and its vunerable to fracutre
What can we do to a cavity to prevent ditching?
Use a lining material - helps spread force down long axis of tooth instead of placing stress on interface between tooth and resotration. Reduce stress on amaglam therefore reducing creep and therefore ditching
Remove all caries
4 factors contributing to secondary caries
Poor OH
Fracture of resotration or enamel at margins causing dithcing and has compromised any seal between tooth and resotration
No lining material - dentine has no protection from bacteria and endotoxins
Microleakage due to no chemical bond between tooth and restoration
Principles of cavity prep
identify and remove caries
Remove enamel to identify extent of lesion at ADJ and smooth enamel margins
Remove peripheral caries at dentine and circumfertinally deeper
Remove deep caries over pulp
Outline form modification - occulsion, enamel finishing, requirement of material
Internal line modification - internal line and point angles
5 risks factors for high caries
Poor OH Poor diet Freq of sugar intake Surgary meds Types of drugs which causes xerostomia Susceptible tooth surface - tight contacts, pits and fissures, receded gingva
