The patient records his pain as an initial pain on the Heath-Parker Visual Analogue Scale (VAS). This pain measurement method involves a 180 mm line with descriptive words that differentiates patients on a line where the best describes their pain. In order to design a standard injection of the maxillary nerve block in all patients, using Aspirating Dental Injection Syringe, Novocol Ontario, Canada, the needle of the 27 mm long 35 mm (Septoject, Septodont, Saint-Maur-des- Fosses cedex, France) Lidocaine 2% with epinephrine 80000/1 mixed with magnesium sulfate or distilled water, injections in the retro-cell region and cm1 above the occlusal mandibular plan. After insertion of the needle at a rate of 3-5 mm into the tissue, aspiration was performed and about 2-3 ml / 2. It is injected from the contents of the cartridge, the syringe 1 mm is returned to the bone hard tissue (in the form of the syringe body in the perimmel area of the opposite side), and after the aspiration of the contents of each cartridge in a 1 minute period It is injected. After 15 minutes, in case of numbness of the lips, the patient begins to study and the access cavity begins on the desired tooth. In each of the stages of acquiring the access cavity or entering the initial file to the canal, in the event of pain, the treatment is suspended and the patient signs his pain on the pain assessment chart based on the Heft-parker VAS and at this stage the study It's over. In the absence of anesthetized lips, the patient is excluded from the study and after completing the injection, the root canal is given.