Teeth are a little different from bone in their structure. Bone tissue is constantly being rebuilt over a lifetime, which is why bone loss is common with long-term prednisone use. Suddenly the amount of bone being built is less than bone being destroyed. Tooth enamel, once formed, doesn't rebuild itself over a lifetime. You can strengthen enamel with topical fluorides, but once formed (around birth and just after for most permanent teeth), it doesn't readily rebuild itself. This is why you get cavities in your teeth, but you don't get "cavities" in your bones. (your bones can heal; enamel, in most cases, can't.)
That being said, prednisone is absolutely, definitely, a contributor in tooth decay, especially if it's used over the long term. Why? Prednisone decreases salivary flow (it dries out your mouth), depriving your teeth of their natural toothpaste, and making the mouth environment more acidic. When your mouth is dry, your teeth tend to be more sensitive to hot, cold, and sweet. Also, prednisone can cause changes in your gum tissue. Many of my patients complain of bleeding gums, or gum swelling, or teeth loosening, while on this medication. When gums are infected, the bacterial load in your mouth is higher than normal, so the bacteria that cause cavities are more active (there are more of them around.)
The moral of the story: If you're on prednisone, especially for the long term, make sure you are getting good, regular care from a trustworthy dentist. Also, make sure your diet is not a contributing factor to possible decay--take only 3 meals per day, with no more than one snack. DON'T sip on sugary drinks between meals to wet your dry mouth. (Use water instead, or a mouth wetting rinse like biotene) Use a fluoride toothpaste (for sensitive teeth if you have the sensitivity issue) and consider using a fluoride supplement like a gel or rinse. Increase your daily brushing to after each meal.
Prednisone is no fun, that's for sure. I've only had to do 4 tapers of 6-8 weeks each since my diagnosis, and I'd much rather sit where I do now, with mucous and some urgency (but minimal D), than go back on the prednisone and have my body function like it did pre-diagnosis. I'll take my normal personality and no side-effects, thanks!
Pancolitis, diagnosed July 2006, at age 29
(Colonoscopy January 2008 showed active disease just in sigmoid and below!)
Imuran & colazol daily; Rowasa and/or canasa rectal meds as needed for maintenence
Currently pregnant-due October 2009