I have had no trouble with my teeth since I got them all done last year. Being a Hashi patient I did have horrendous trouble with pain, chipping, etc. But I doubt it is the Synthroid causing your pain. Perhaps a dental check up might reveal something. Always good to have a check up once a year anyway!
I have had teeth problems since diagnosis of Graves so think it is thyroid related and not medication related.
There are may here who have teeth problems now.
I don't know about the synthroid causing it but I know when I was hypo my teeth hurt.