Hi there, thank you for your excellent questions. Althought their bone-building effects are somewhat comparable, there are indeed differences among bisphosphonates such as Fosamax and Actonel. Different physicians may prescribe particular ones for individual situations, and it can be unfortunate when insurances try to encourage a  "one-size (or medication) fits-all" approach. This issue -- of whether Fosamax or its generic equivalent should be the first line of treament for most osteoporosis patients -- has generated a great deal of controversy in England, for example. In any case, you are right that Fosamax is uncoated and Actonel is coated. When you mention difficulty swallowing, please be aware the Fosamax web site (www.fosamax.com) advises "Stop taking FOSAMAX and call your doctor right away if you develop new or worsening heartburn, difficult or painful swallowing, or chest pain because these may be signs of serious upper digestive problems, which can include irritation, inflammation, or ulceration of the esophagus." Even if you are back on Actonel and not having difficulty swallowing, it is important for your physician to be aware of your condition. All this, however, is a separate issue from your sister's dental problems. You didn't mention the specifics of what those issues are, but you should encourage her to make sure her dentist/oral surgeon is aware of her bisphosphonate regimen, and that her osteoporosis specialist is aware of her dental problems. Best wishes to the both of you.