Hello,
Sorry to hear that your dad has been having pain with his teeth. I also have MM and had the same problem a few months ago. In fact I had several abscess come up which were very painful. I had to have root canal work done. I am on Bonefos - which is Sodium Clodronate and read an article that it has been discovered that this can cause problems with the teeth and jaw bones. I stopped the Bonefos while the work on my teeth was carried out but have now started the tablets again. My consultant says that the benefit of these tablets (to strenghten the bones) far outweighs the problems it can cause the teeth.
It is really important that your dad cleans his teeth two, or even three times a day and regularly sees his dentist. In fact, the article which I read, says that you should have the teeth completely checked over, fillings done etc., before starting the Bonefos - I think that the Zometa sounds the same type of thing.
Hope this will be of some help.
Good wishes Phyl