Composite resin fillings are a cosmetic alternative to amalgam fillings, which have a metallic appearance unsuitable for front teeth restorations. Polymer resins can be given any desired color to match the tooth being repaired and the neighboring teeth. This aesthetic feature is the main advantage of the composite over the amalgam. Minimal tooth preparation using acid etching is required as they bond micro-mechanically to the tooth enamel. They show good resistance to fracture in small fillings which are exposed to moderate chewing pressures.
Because of their bonding capability, composites can be used to restore teeth that do not have sufficient structure to hold amalgam fillings. Although more costly than amalgam, composite fillings can be cheaper alternatives to metallic crowns. They are more versatile than the amalgam in that they can be used to repair a broken tooth or even minor enamel chip off. Furthermore, composite fillings can be repaired easily.
From environmental and health points-of-view, composite resin fillings can give peace of mind to those concerned about the release of mercury from an amalgam filling. Another advantage is that they are not susceptible to corrosion like amalgams are. On the minus side, the composites do not have the strength of the amalgam, are more costly, suffer from shrinkage (albeit very low) during setting, and demand greater expertise and time by the dentist. The latter is the main factor in their higher price point.
Because of their weaker strength and hence shorter life expectancy, composite fillings are not covered by some insurance plans. Since molars have to bear a very high chewing pressure, composite fillings may not be considered suitable for the repair of rear teeth. Since cosmetic concerns are not very important for these teeth, amalgams will generally be preferred for molars.