DMS Tutorial
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What is hardness?
resistance to permanent surface indentation
knoops vs vickers hardness
vickers hardness = measure of hard metals/alloys knoops hardness = measure of composite
What is compressive strength?
maximum compressive force the material can withstand before permanent deformation
What is wear resistance?
the ability of a material to resist the progressive loss of volume from along its surface through mechanical actions such as repeated rubbing, sliding, or scraping.
What should always be known before using a light cure material?
depth of cure
What is bond strength?
strength of micromechanical retention of the bonding agent into the etched surfaces of enamel and primed dentin.
What is the bond strength of composite usually?
typically between 20-40MPa usually 10% of compressive strength
What is the compressive strength of composite usually?
300-400MPa
What does shrinkage cause?
leads to gaps > fractures > ingress of fluid > microleakage > secondary caries
What is young’s modulus/elastic modulus?
Resistance to elastic deformation of a material by force that is calculated as the ratio of elastic stress to elastic strain.
What happens if the stress is higher than the elastic limit?
permanent deformation
What is young’s modulus for composite, enamel, and dentine?
composite = 15 GP enamel = 60 GP dentine = 20 GP