Several companies do "worldwide" policies, including Swiss Life, BUPA and April from memory. You could usefully have a chat with Nick Chubb at
http://www.asttral.com/
who is a broker and pretty straight in my experience.
There is a list of web addresses of several insurance companies here:
http://www.completefrance.com/cs/forums/1017162/ShowPost.aspx
PPP (aka AXA) do an International scheme which isn't actually worldwide but does cover Europe.
Whilst resident in UK I was covered with PPP via my employment but since moving to France and being transferred to an International policy all the documentation now says AXA who are a French company as you probably know.
Depending on the scheme chosen limited dental cover is available with the proviso that you undergo 6 monthly checkups.
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