Composite filling usually last longer than 8 years on AVERAGE, but it can
vary according to the circumstances of each filling and the tooth in
question. Dentists may not want to claim more than 8 years because some
composites will fail early and they don't want dissatisfied patients.

Your mother probably has silver amalgam fillings, which contain about 50%
mercury, 35% silver, 11-12% copper, 3% tin, and sometimes 1% zinc. Mercury
is the problem here, for the same reason that it is a problem in tuna fish.

One average silver amalgam filling contains enough mercury over its lifetime
in the mouth to exceed the United States Environmental Protection Agency
Adult Intake Standard. Animal and human autopsies demonstrate that mercury
builds up in the body over time. It is detected highest in the kidney,
stomach, jaw, and liver. It can pass through the placental barrier to the
unborn child. Some countries have banned their use, or prohibited government
insurance payments for amalgam fillings.

If your mother's fillings actually were lead, that would be a worse health
hazard than silver amalgam. Lead has been banned in paint and gasoline, and
for good reason.

    Keep your teeth clean.  Brush and floss properly.  Maintain a good
healthy diet.  Visit your dentist regularly.

    Not in any kind of predictable way.  Generally larger fillings have a
higher probability of failing, no matter what they're made of.

    I am not good at fortune telling.  What could give you a clue, since
you are going to your dentist regularly, is if you are continually
getting new cavities each time you go, or if your fillings are mostly
stable, with the occasional cracked filling or tooth needing replacement.
    If you are still getting new cavities with this level of oral hygiene
and professional care, something needs to change.  Your dentist should
be able to discuss this with you--or find a dentist who will.

Good luck,
Steve

Not true. Many last nine or more years. Some people try
not chewing to provide longer lasting service, but we
buried three, maybe four of these patients this month alone

--
Joel34