using resin composites Flashcards
What are the principle methacrylate monomers?
BISGMA - most common
Urethane dimethacrylate with diluted monomer eg. TEGMA
Describe the composition of composite
Principle methacrylate monomers Filler Silane coupling agent Activator Pigments
What is the function of the filler?
Gives strength
What substances make up the filler?
Particles of silica based glass + barium oxide
What is the function of the Silane coupling agent?
Costs fillers to allow mixing with matrix
What is the main activator in composite
Camphorpuinone ( light activated)
What are the functions of the pigments?
Give different shades
What are the 3 classifications of composite resins?
Macro filled
Micro/nano filled
Hybrid
What are the properties of micro filled composite?
High resin : filler content Less strong Shrink more More translucent More vital appearance Easily polished
What are the properties of macro filled composite ?
High filler: resin content Stronger More wear resistant Shrink less More opaque Less vital appearance Difficult to polish
Describe the properties of hybrid composite
Mixture or micro and macro filled
Used anterior and posterior
What are the advantages to resin composites?
Wear resistant and compressive strength matches tooth structure
Command set
Good aesthetics
Bonded to tooth - more conservative
What are the disadvantages to resin composites ?
Polymerisation shrinkage
Moisture control essential
Can be brittle in thin sections
Depth of cure 2mm- incremental placing required
Describe techniques to over come polymerisation shrinkage
Good moisture control as material Is hydrophobic
Ramped output from light source
Place in oblique increments
When do you intervene re. Resin composites?
Caries reached ADJ
obviously cavitated
Caries evident on radiograph
