When I was a child my dentist shoved a sharp dental pick into the center of my molars with great force, so hard that I couldn't keep my head up. Think about what does that do to a tooth. It makes a hole, a 'cavity", that then had to be filled with a filling. A mercury filling. I have lots of mercury fillings.
Many hack dentists perform "preventive fillings" that are a preliminary strike before the cavity or problem even exists. Well, teeth constantly gain and lose enamel - many cavities and pits are normal wear and tear that your body heals by itself by remineralization (a scientific fact). Many hack dentists see a healthy untouched tooth as an opportunity to make money. Drill fill and bill.
I had 3 of my mercury lozenges replaced with composites and I regret it - I should have went with something better because the composites are deteriorating quickly and 2 of them need replaced after only a few years - with that frquency of replacement those teeth will be drilled out, dead, and in need of root canal/extraction in no time. Plus the composites cause a reaction in my mouth that is either a bio-reaction or a chemical reaction between the aluminum in the composites and the mercury in my amalgams. Aluminum and mercury react violently. Do dentists consider that? No.
My advice? Get fillings that last. Check the mercury-free links like IAOMT.org to find dentists near you. And, this is important - make lots of phone calls to get recommendations from people about who to go to. Call places like dental labs in your area - some are obviously biased but some labs are great sources of information. Tell the lab you have a lot of inlay or crown work and want to find a lab to do good work before you chose a dentist. Ask them what the best materials are and how long they last. Ask what they put in their own mouth. Email activists against mercury and ask them for advice. A lot people are eager to share their story - some of the best advice I have recieved was from dental lab technicians or owners who's job it is to know about dentists. You should be able to tell the biased people from the genuine. I have talked to a lab tech who called me a "problem patient" because I brought up the word MERCURY. I also had a very positive and revealing 2 hour long conversation with a lab owner when I brought up the word MERCURY. Some are in the "good ol boy" network and will only recommend the dentists they work with, and some will off-the-record tell you what you need to hear about dentists.