I know a lady at work who has UC, we were complaining together about how much we hate prednisone and she mentioned "oh and it makes my teeth hurt sooo bad!" and I was like 'OMG ME TOO, I thought I just need to use fluoride more often or something".
I went to the dentist and asked if he could give me a fluoride treatment or two, since that helps with tooth sensitivity and I told him I was on prednisone and he was like "oh yeah, that stuff will make your teeth hurt for sure, you also have to worry about damage to your bone structure in your mouth where it will can your teeth more likely to fall out".
I asked him if my teeth were yellow all the time from the prednisone and he said "kinda, part of the problem is that the prednisone seems to damage your enamel and/or keep it from rebuiding itself the way it usually would. when your enamel isn't being maintained properly your teeth hurt, and when your enamel is thinned out you can see the dentin of your teeth more clearly, and the dentin in your teeth is more yellowy than your enamel usually is."
So...yeah, between the vitamin deficiencies and steroids, having crohn's can really mess up your teeth. I'm gonna throw my lot in with the "dentures are awesome" boat, I have heard nothing but horror stories from people who tried unsuccessfully to save their teeth or replace individual ones, and people with dentures said the only bad part was getting their other teeth pulled to have the dentures installed. Plus, dentures are waaaaay cheaper.