you are not crazy!! the dentist are crazy 100%!!!!! they are the mad hatters of this century!! aftter all they are exposed to a great deal of mercury at all times!!! in there office!!!! im sure of it mercury is in there carpet!!! on there clothes!!! *you get the picture* as for porcelain there are no documented cases of allergic reactions however there have been rare allergic responses when it is fused to meatal such as gold & nickel or cobatl-chrome...