Properties of Resin Composite (White Filling Material)
What is Resin Composite Made of?
Resin composite is a combination of chemically distinct materials with an interface separating the components. Resin usually consists of a matrix (bis-GMA, UDMA, and TEGDMA) and fillers (very small particles, in some cases nano-particles) (quartz, zirconium, barium glass, silica) that provide the strength, abrasive resistance, radio-opacity, aesthetics and handling properties.
Strength, Colour, and Polish
The composition of resin composite can very depending on many factors that are sought after, such as; strength, colour, handling, and polish-ability . For example, resin composites with small particle and hybrid systems polish well and are very strong; Whereas, micro-fine systems have excellent polish-ability but low fracture strength. Thus, there is a desire to make the filling material as strong as possible, with balance for being able to have a high lustre.
In a Flash of a Light: How does Resin Composite set?
Resin composite starts off soft (almost like a putty), after appropriate preparation the resin is then placed into the prepared cavity. Light exposure with the correct wavelength (blue light) is then used to start the reaction within the resin to allow for polymerization. The process involves a photo-initiator camphorquinone, and a amine accelerator, which starts a chemical reaction to allow for cross-linking and polymerization of the resin composite.
Resin Composite: Advantages
Advantages of resin composites as a restorative material include:
- Increased aesthetics (large number of shades, stable colour)
- More conservative of tooth structure (adhesive preparation vs mechanical retention)
- Adhesive to tooth (seals margins, supports unsupported tooth structure)
- Less thermal conductivity
- No galvanic reactions
Resin Composite: Disadvantages
- Polymerization shrinkage (depends on filler)
- Cuspal deformation during polymerisation
- Gap formation at restorative interface
- Marginal integrity
- Water-sorption an associated breakdown of filler-matrix bond
- Depth of cure