That “unskilful and unscrupulous Dentists fill with tin covered with gold, thereby causing galvanic action, pulpitis, death of the pulp, abscess, and loss of the tooth,” has certainly not been an accepted creed in this country, for I was early taught the use of this material both alone, and in combination with gold, when I first commenced the study of my profession with Mr. Sheffield, of Exeter, and long experience, and the retention of a tin filling in my own mouth, in a perfect condition for over five-and-twenty years, has fully proved to me the value of this metal. When used in combination with gold, and exposed to contact with the fluids of the mouth, it certainly undergoes a chemical change, becoming nearly black in colour, but without staining the tooth as some amalgams do; it also becomes harder, and cuts harsh like an amalgam filling, but the change does not appear to cause any alteration in its bulk, or in any respect to interfere with its efficiency as a filling, nor have I ever found it produce any of the evils suggested in the creed, and I cannot but think that it would be more used, were it not for the universal prejudice that exists in the mind of the public in favour of gold, partly arising from the magical charm which resides in the word gold, and partly from the nothing but gold theory (if I may so call it), which has been so largely spread by our American brethren. That “a filling may be the best known for a tooth and yet leak badly,” seems a simple admission that in some cases bad is the best that we can do for them. If experience has taught us anything, it certainly has proved that it is the leak which does the mischief; and as in warfare no fortress is considered stronger than its weakest part, so is it with a tooth that is filled. A small leaking point will soon undermine the filling, and prove its ruin. The statement that “gutta-percha _properly used_ is the _most permanent_ filling material we possess,” must make us wish to know the meaning of the words, “properly used,” for the rapidity with which it wears away, in any position in which it is subjected to friction in mastication, seems to me to prevent the possibility of its ever being permanent. The force of the article which says that “a poor gutta-percha filling, _in its proper place_, is better than a _good_ gold one,” seems to depend on the question as to what is the proper place for a gutta-percha filling: surely not the place where we can insert a good gold plug, if by “good,” is meant one that is not only solid, but also sufficiently tight to exclude all moisture from the cavity.