Most people would agree that a white or porcelain filling looks better than a silver filling.  But of course how a tooth looks is not always what is most important.  Although there are advantages to having newly filled teeth done with the white filling there are some distressing disadvantages to having already existing silver fillings replaced by white fillings.  It is a personal decision and some are willing to face the discomfort and risks to have a smile that they do not feel self-conscious about.  In any case before you make a decision, you should speak to your dental health professional and review advantages and disadvantages of the options that are available to you.

Advantages of White Fillings:
    No more "mouth-full-of-silver" look whenever you smile big enough for someone to see into your mouth.
    There is some vanity involved when it comes to having all of your silver fillings replaced.  Many times, you will have already started having your fillings filled with the white material and are changing out your old silver ones so that all the teeth in your mouth match.

Disadvantages of Silver Fillings
    Many people are concerned about the amount of mercury in silver fillings.
    Some are allergic to the mercury in the amalgam filling.
    Teeth turn gray from the silver seeping through the tooth enamel itself.   Although this is normal with fillings that were made of the silver amalgam from the 1970's.  Teeth can begin to look much like teeth that are "dead" or that have sustained some sort of damage.
    Unfortunately silver filling discoloration will usually get darker and darker with time.

Disadvantages of White Fillings
    Serious dental work is possible and when you have serious dental work there is a higher likelihood of future problems.
    The dentist may decide to have you come in on two separate days so that only one side of your mouth is numbed at a time.  But this means setting aside the time for multiple dentist visits that can be several hours in length.
    The process of removing old silver fillings meant that the silver was not only removed but space needed to be made for the new white filling. This translates into more drilling and more whittling down at the teeth to find a good surface for the new filling to adhere to.
    Some teeth have to be drilled so much to remove the silver filling that a crown must be made for the tooth.  Wearing down the teeth can lead to cracks, sensitivity and hidden fractures in the future.
    Replacing silver fillings with white ones means disturbing the balance of your mouth.  The surface of your teeth will most likely change and with that comes a different bite.  Because biting and chewing exert so much force there can be problems with your jaw or even just problems eating your food.
    During the replacement process teeth left untouched for years are exposed to air and a new filling material.  In addition the tooth has to become accustomed to a new material and a new fit making nerve ending particularly sensitive.
    White fillings are said to not last as long as silver fillings.

Advantages of Silver Fillings
    Last twice as long as white fillings
    Avoid the additional dental work and risks of having the old silver fillings removed and replaced.