Dental fillings may be tooth colored or metallic. Historically dental amalgam, a metallic mixture containing mercury, has been used for nearly 150 years. Controversy has risen and fallen concerning the speculation of health hazards associated with mercury. Despite periodic outcries, the scientific evidence concerning the safety of dental amalgam is undeniable.
Clinically amalgam fillings are among the longest lasting of dental restorations. In the last 35 years filled resin based fillings have gained popularity because they are tooth colored and require less tooth reduction to stick to the teeth they are restoring.
Resin based filling materials are also called composites because they are a composed of a resin and fillers. The composites I used in dental school were filled with relatively large ground ceramic particles. Now the composites are filled with nano-size particles which permits smoother and shinier finishes than before.