Here is a bit of general info I picked up on the internet relating to how it works in France:
In relation to prostheses and orthodontic (teeth or jaw irregularities) treatment the cost of the work generally bears little relation to the level of reimbursement.
Here, dentists are entitled to impose their own charges.
Thus, the current official fee for a ceramic ‘crown’ is around €100 whereas the fee charged by the dentist might well be as much as €1000! And remember you only get 70% of the official rate!
These rates are charged because the official rates for general treatment are considered to be so low by dentists that they see this as the only way they can make some money!
In theory, dentists are only entitled to apply reasonable rates for such treatment, but enforcement is weak. You are entitled to ask for an estimate of the cost of the treatment before it is carried out.
Such is the scale of charges for a 'crown' and other related treatment, it is becoming increasingly popular amongst the French to go abroad for treatment, often to Hungary or Morocco, where prices are three to five times lower than in France.
If you are prepared to live with a metal ‘crown’ the charges are more reasonable, as there is an agreement on fees between the government and the dentists profession.
If these things worry you, by law the dentist is obliged to provide you with detailed estimate of the proposed treatment. Sadly, however, it will not make the price any lower!