Describe features of resin composites.
- Growing number of patients opting for these over dental amalgam
- Permits less invasive treatments
- Susceptible to polymerisation shrinkage
- Potential allergenic effects of BIS GMA & TEGDMA if not bound in a resin matrix
- Bisphenol A oestrogenic effect
- BISGMA cytotoxic in a number of cell cultures
what is an Ormocer?
- Organically modified ceramic technology
- Essentially a monomer free matrix consisting of 3-dimensionally cross linked copolymers in which inorganic silanated filler particles :
- Provides abundance of polymerisation opportunities
- As a consequence no residual monomer
what are the 3 components of ormocer?
- silicones
- Organic polymers
- Ceramic glasses
what do the relative proportions of these structural elements determine?
the materials properties
For desired application , what does the manufacturer choose?
- The base materials
- How the inorganic poly condensation reaction is conducted
- The linking reactions which lead to the construction of the organic network
what are the physical properties of silicones?
- elasticity
- surface energy
- gas permeability
what are the physical properties of organic polymers?
- toughness/ flexibility
- functionalization
- processability
what are the physical properties of ceramic glasses?
- hardness
- chemical / thermal stability
- transparency
Describe how Ormocers is manufactured.
-Commence with build up of inorganic network:
Controlled hydrolysis and condensation of organically modified Si alkoxides
-Then form organic network:
Application of heat/UV initiate reaction of polymerisation of polymerisable units
-Results in an inorganic-organic copolymer
how can you further customise properties of Ormocers?
addition of: -particles -fibres -weaves (all of varying composition)
How are Ormocers used in dentistry?
- Ormocer based composite restoratives (Admira, Definite)
- Light cured Glass polyalkenoates
- For composite must use dedicated product bonding agent
what did the Ormocers dentist composite claim?
- Have less shrinkage on setting
- No residual monomers
