Direct Composite Resin
A composite resin is tooth-colored plastic resin filled with glass (silicon dioxide). Introduced in the 1960s, the original dental composites were limited in use to filling enamel defects in the front teeth. Two main problems stopped composites from becoming a universal filling material. The biggest problem was that we could not bond to the inside components of the tooth (dentin). This problem was overcome in the 1990’s with the advent of dentin bonding. This ability to bond to dentin has revolutionized modern dentistry allowing us to bond composite resin fillings to any part of the tooth. The other problem was that composites were originally not strong enough to withstand the pressure and wear generated by the back teeth. Since then, composites have been significantly improved and can be successfully placed in the back teeth as well. Today composites are not only used for restoring decay, but also for cosmetic improvements of the smile by changing the color of the teeth or reshaping disfigured teeth.
How Long Does It Take To Place A Composite Resin?
It takes us about 10-20 minutes longer to place a composite than a silver filling. Placement time depends on the size and location of the cavity. The larger the size, the longer it will take.
What are the advantages of composites over mercury silver amalgam?
- The biggest advantage is that a composite filling is bonded to the tooth. Thus a composite filled tooth has strength almost equal to an unfilled tooth. An amalgam just sits there filling the space providing no structural strength whatsoever. As a result amalgam weakens the tooth leaving it more prone to fracture.
- Another advantage is that mercury silver amalgam requires the removal of much more tooth structure when it is first being placed. Amalgam requires a certain bulk or else it cracks. Also since amalgam is not bonded the initial preparation always involves extending the tooth removal beyond the actual cavity and into every pit and groove on the tooth. Composite resin can be placed in very small cavities allowing dentists to confine tooth removal only to the actual cavity, resulting in very tooth conserving preparations. Remaining grooves and pits are then bonded and sealed with resin.
- Esthetics is another advantage, since we can blend shades to create a color nearly identical to that of the actual tooth.
How long will composites last?
Studies have shown that composites last 7-10 years, which is comparable to silver fillings except in large fillings, where only porcelain should be placed (see porcelain fillings).