_In pain due to necrosis of the socket_ deodorant antiseptic injections must be used, while in extensive laceration of the soft and hard parts an anodyne mouth-wash[21] may be tried. In all _obscure cases_ an application should be made to the socket of some local anodyne such as tincture of opium or cocaine, and a mouth wash having similar properties should at the same time be prescribed. (4) DIFFICULTIES, COMPLICATIONS AND SEQUELÆ ARISING DURING EXTRACTION UNDER ANÆSTHETICS. (_a_) =Tongue slipping back.=--During extraction under anæsthetics the tongue not being under control may slip over the larynx, or may be forcibly pushed back by the fingers of the operator. Symptoms of difficult breathing or even arrest of respiration will follow this accident. It is not enough to watch the chest walls, as respiratory movement may continue without air entering the lungs. Treatment consists in pulling the tongue forcibly forward with a suitable instrument and forcibly extending the head on the spinal column. (b) =Forcing out a tooth with a prop or a Mason’s gag.=--With a prop this accident may arise from resting it upon teeth which are loose or from placing it in such a way that undue leverage is brought to bear on the teeth. It is an accident most likely to occur when the prop is fixed on the front teeth and the mouth opened to its widest extent. Under such conditions undue leverage at right angles to the long axis of the tooth is brought to bear upon the palatal surfaces of the upper teeth and they are consequently forced outwards. With a Mason’s gag the accident is due at times to clumsiness; great care should therefore be exercised when using this very powerful instrument. If a tooth is forced out it should if possible be immediately replaced. (_c_) =Passage of a foreign body through the isthmus of the fauces.=--A foreign body, such as a tooth, a broken piece of forceps or a prop, passing through the isthmus of the fauces may become impacted in either the air or food passages. In the air passages it may lodge (1) over the entrance of the larynx, (2) in the larynx, (3) in the trachea or bronchus. In the food passages it may lodge (1) in the pharynx, (2) in the œsophagus, (3) at the pyloric opening of the stomach.