The professed incompatibility of gold as a filling material with tooth bone, seems to me to be at variance with the frequent success which we all must have experienced, in the use of that filling in cavities on the labial surface of the roots of the upper incisors. I mention this particular position as being easy of access for operating, and also as being one where the enamel, tooth bone, gold, and saliva, are in constant contact with each other. In those cases where the success of the operation has not equalled our expectations, in endeavouring to estimate the probable incompatibility of the filling material as a cause of failure, it is, I think, necessary to consider whether in the ordinary operation for filling, the whole of the diseased dentine has been so thoroughly removed, as to admit of its proving a satisfactory test case, for the microscope reveals to us a change in the dentine in the sides of a decayed cavity, even when it appears sound to the eye, and also to the feel of the instrument; and in those portions of the margin of the cavity which we undercut for the retention of the filling, we have the dentine not only denuded of its nutrient covering, the periosteum, but also deprived of its nutrition from the pulp by the severance of the tubes of the dentine, and the intervention of the filling material, and in this deteriorated condition, in all probability still exposed to the continuous action of the same deleterious influences (whatever they may have been) which first caused the decay; and I cannot but think that the failure when it occurs, is in a greater measure due to the above named causes, rather than to the incompatibility of the gold with the tooth bone; but with all the success that has attended the use of gold for so many years, we must still, I am sure, be willing to admit the want of a perfect plastic filling, which shall be able to withstand the friction of mastication, and also the deleterious action of the fluids of the mouth. The dictum that, “a tooth that can be so treated as to be satisfactorily filled with anything, is worth filling,” is one, I think, that all who value conservative surgery must readily agree with.