What are the 2 types of elastomers?
- Polyether
- Addition silicones
What are the key properties you need to assess for elastomer IM’s? (8 points)
- Flow/viscosity
- Surface detail
- Wettability
- Elastic recovery
- Stiffness (flexibility)
- Tear strength
- Mixing time
- Working time
In the ISO regulations, the grooves/indentation of either __um or __um (depending on material viscosity) are replicated?
20 or 50
What is it that is in elastomer materials that ensures exceptional precision and excellent reproduction of anatomical details?
- The combination of the polymer and innovative spheroid silicon micro-fillers
What are the properties of IM’s that relate to the quality of surface interaction between material & tooth/soft tissue surfaces? (2 points)
- Viscosity
- Surface wetting
What are the properties of IM that are related to accurac y? (2 points)
- Surface reproduction
- Visco-elasticity/ elastic recovery
What are the properties of IM’s that relate to dealing with the removal and undercuts? (2 points)
- Tear/tensile strength
- Rigidity (flexibility)
What must the viscosity of IM’s be like?
Must be able to flow readily
What must the surface wetting of IM’s be like?
Must make intimate contact with the teeth/mucosa
What is viscosity?
A measure of material’s ability to flow
- Determines a material’s potential for making close contact with hard/soft tissue surfaces
What must the surface wetting of IM’s be like?
- IM must make intimate contact with teeth/mucosa surfaces
- SO ALL OF THE SURFACE is replicated
Ideally, what do we want the elastic recovery of an IM to be like?
- want 100% elastic recovery
- NO permanent strain
What is viscoelastic behaviour?
- When IM, having been stretched/compressed on removal from mouth, fails to return to its original dimensions/shape
What do we want the viscoelastic behaviour of IM’s to be like?
Want low viscoelasticity (small deformation)
What is tear strength?
The stress a material will withstand before fracturing
What do we want the rigidity of IM’s to be?
Has low rigidity as want the IM to be flexible
