Fundamentals of dental materials Flashcards
Enamel
Rod sheath
Narrow space around 3/4 of each rod keyhole shape
Dentin
Inter-tubular dentin is
structural components of the hydroxyapatite-embedded collagen matrix- bulk of the dentin
Dentin
Peritubular dentin
limited to the lining of the tubular walls- little organic matrix densely packed with appetite crystals
Atomic Building Blocks
Covalent Bonds
Strongest and simplest
Properties of materials
Biological
toxicity and sensitivity reactions that occur locally or systematically within associated tissues
Properties of materials
Surface energy
a low surface energy liquid will readily spread over a high surface energy substrate
Properties of materials
Wettability
the measure of the affinity of a liquid for a solid indicated by the spreading of a drop
Properties of materials
Sorption has two categories what are they
Adsorption and Absorption
Adsorption
dissimilar substances in intimate contact with the surfaces of a sold=adhere
NOTE: high energy surfaces will adsorb molecules more readily than low energy surfaces
Absorption
the uptake of a liquid by a bulk solid. the substance absorbed diffuses into the solid material.
Biocompatibility Tests
Usage tests
material is placed in a situation identical to its intended clinical use, human or animal trials (clinical trials)
Pulpal reactions
Microleakage
materials may not bond with sufficient strength to resist contraction on polymerization, wear, thermal cycling
Microleakage also
can be caused by Gap between tooth and restoration allows influx of materials that may irritate the pulp
Threats from removal of the smear layer
Acids used to remove smear layer are potential source of irritation
The acid used to remove smear layer are potential source of irritation depends on
- Remaining dentinal thickness (RDT)- 0.5mm/min
- strength of the acid
- degree of etching (odontoblastic processes may be affected even if acid does not reach the pulp)
