Occasionally the “control” over-laps, in which case it is necessary to use also the finger next to the zone finger, and in the case of wisdom teeth, to get the best results it is sometimes advisable to use both the third and the little finger--as the fourth and fifth zones merge in the head. A very successful method practiced by some experts--particularly where extraction must be done--is to grasp the offending tooth as near the apex of the root as is practicable, and with the thumb and finger make firm pressure for three, four, or more minutes--by the watch. This usually produces a degree of anaesthesia lasting about one half hour, although pressure can, if necessary, be reapplied at any time. Other dentists and oral surgeons get excellent results by pressing on the “heel of the jaw”--the point directly back of the wisdom tooth, ponderously known as “the tuberosity of the superior maxillary.” This produces a very complete and lasting anaesthesia of the entire jaw of the side affected, and permits of the painless extraction of teeth living in the immediate neighborhood. [Illustration: FIG. 25--Pressure at I, Fig. 4, with thumb and finger will anesthetize both thumb zones, inasmuch as the pressure is brought directly on the median line and to the right and left of it. Pressure at II (pressure on inferior dental and lingual nerves) will anesthetize not only entire jaw on side compressed, but to a greater or less extent the entire half of the body. Pressure at _a_ with thumb and finger will often anesthetize that zone sufficiently for painless extraction. Any tooth may be prepared similarly. Pressure at _b_ with thumb and finger anesthetizes bicuspids and occasionally molars. Pressure at III will aid materially in anesthetization.] With the lower front teeth, it has been found that to press or hold the inferior (or lower) dental nerve, where it enters the ramus (or groove) of the lower jaw, gives good anaesthesia. Also pressure with the finger on the inferior dental nerve, where it exits from below the bicuspid tooth (called by doctors the mental foramen) will usually anesthetize that half of the jaw. Many operators, the better to “focus”, prefer to use the blunt end of an instrument (the handle of an excavator is excellent) upon this inferior dental nerve. The proper application of these principles cannot fail to be of immense value to the dentist and oral surgeon in their daily practice. In relieving toothache and neuralgia, in removing deposits, in extracting teeth, and in fact in most painful operations which dentists are called upon to perform, this pressure technique should prove invaluable, as many dentists are learning every day.