COMPOUND STRUCTURES Flashcards
restoring compound structures involves
restoring structure restore form and colour/shade resist functional/parafunctional forces resist wear and degradation resist static and dynamic fatigue
relevant properties of restorative materials
elastic modulus compressive strength flexural strength fracture toughness coefficient of thermal expansion wear behaviour fatigue behaviour
coefficient
composite 50 pp degree
tooth 10pp
this will fatigue the tooth therefore likely break if not succinct
composite material defintion
a single entity containing two or more constituent phases
composite fillers purpose
reduces polymerisation shrinkage
limits fracture propagation
improves wear resistance
improves optical properties
compound system definition
functional unit comprising of two or more consituent mateirals eg PFM, enamel to dentine, porcelain bonded to metal
systems involved in joining materials in compound system
specific adhesion
micromechanical adhesion
mechanical interlocking
useful interactions between materials in a compound system
complementary properties
mechanical protection
adhesion
unwanted interactions between materials in compound systems
electromechanical corrosion
mismatched thermal expansion interface damage
unstable dimensional form
constructional forms of materials
block form eg intracoronal restoration
shell form eg crown
laminate form - eg porcelain laminar veneer
how do constructional forms affect how they work
block form- takes load in its mass, avoids fracture propagation
shell form - deforms slightly
laminate - works by being bonded to underlying tooth strucutre
adhesive interface assembleies
need interface to be well bonded to both substrates
- want occlusal load to be moved through the whole of the materials through to dentine ect effectibeyl
effective adhesive assembly
strength of the bond to the restorative substrate
strength of the bond to the tooth
durability of the chemistry
cohesive strength of the component material
