In looking over the literature of the above-named subject I have again and again been impressed by the few references to the difference between a cystic empyema, so called, and a true empyema, the one being due to the encroachment of a dentinal or alveolar cyst to the antrum, the other a true infection of the antrum either from dental or nasal origin. In an article on empyema of the antrum in one of our leading dental journals not long ago I noticed a statement as follows: Within the last few years a comparatively new affection, frequently confounded with antral empyema, has appeared. Dentigerous cysts arise as you know about the tooth roots and slowly dilate the tissue at the root of the tooth. I quote this principally to show that affections of the teeth and alveolar process in relation to antral troubles do not receive the attention they deserve. If the