My 2nd molar has a very deep metal filling against the nerve. It has been giving me problems so I probably need a root canal on this molar. My molars are already very short and I don't like how crowns require tooth structure reduction. Could a post and core or onlay be an alternative to getting the molar crowned after a root canal? Is a crown even necessary? Couldn't a filling just be placed? Crowns are just really risky for me because my molars are very short from tooth grinding.