At one time, there were basically two types of fillings.  Silver (amalgam) fillings in the back, and white (composite) fillings in the front.  The technological breakthrough of the bonding process in the late 1970's changed the playing field of the standard of care, where for the first time, white fillings were being placed on back teeth. 

Silver or amalgam fillings have become somewhat controversial over the years due to the presence of mercury in the alloy of metal.  Despite all of the controversy, this is still a material that has a place in the dental office, in certain situations,since it has proven to be so reliable and durable, sometimes lasting for 20, 30, or even more years.  Any discussion about this material could fill pages, thus no single paragraph can adequately cover the topic.  Suffice it to say that after all these years, and countless discussions about mercury toxicity, it still remains a material with important clinical value.

White or composite resin fillings allow us to create cosmetic replacement of diseased tooth structure, very closely resembling the original tooth. We no longer have to accept unsightly patches of discoloration on our teeth.  White fillings have gradually become the new standard of care, not because it is such a perfect material, but because it is what most patients want.  These fillings have greatly improved since their introduction in the early 1980's, and do create a great cosmetic improvement over other alternative materials.  Composite resins are generally not as durable over decades, but provide us with a means of filling both front and back teeth in a cosmetic fashion.  There are some limits to the practical usefullness in certain applications.  It remains the primary filling treatment option for most fillings placed in modern dentistry.