MESSRS. EDITORS—In 1841, the second molar tooth in my "working" side of the under jaw became decayed in the center of the crown and forward, so much so that it was very sensitive. Not being where a dentist was accessible, I undertook the job of filling it. I cleaned the cavities and enlarged them slightly sidewise, and filled them compactly with heavy tin-foil, the only thing I could get; thinking that as soon as practicable I would have the thing more artistically done. It is now seventeen years since I did so, yet the tooth has been used constantly, is emphatically a " working" tooth, and is as sound and strong, apparently, as the day it was filled; it has not (owing, I suppose, to the non-conducting properties of the tin) shown the slightest sensitiveness. The metal seems as durable as gold, and if so, is far preferable on several accounts. I shall never have a tooth filled with anything else, if I should need such work done again. R. H. A. Baltimore, Md., January, ]858.