Aside from sailing, I am a dentist, and what I can suggest is the following.
In any drugstore in the US, you can buy something called temporary filling (over the counter) which costs $3.00 or $4.00. You can also buy a small jar of vaseline. And if you mix them together, you get the closest thing to a dental cement, which you can use to recement a crown while you are off shore. It will also have soothing effect if the tooth that had the crown was a live one, till you can get the necessary work on land.
Also having dental work done in third world countries carries infection control risk.
Using super glue for any dental purpose is incredibly bad idea, except if you lost
a tooth from a denture, where you can glue it back to the denture.
Don't put any super glue on any tooth, live or dead period. if you lost
a filling, don't glue it bad, just use the temp filling to close the cavity till you have it repaired.
Also having Oralgel over the counter on a boat is a very good idea in case you experienced sharp pain all the sudden.
Also if you do any off shore sailing, visiting a dentist before you leave should be added to your check list.
That visit can tell you if you have any dental problem that is waiting to happen.
Having severe dental pain for a few days while you are off shore is not fun.
Hope that would help