An apparatus (20) for a doctor-controlled injection of a dental anesthetic into an intraligamentary tissue of a subject, the apparatus comprising: a drive unit (22) for delivering a drug at least one flow rate； a handpiece (22) to be held by the doctor, the handpiece being connected to the drive unit (22) to receive the drug and being adapted to hold an injection needle (30) to be inserted into the intraligamentary tissue of the subject by the doctor, to pass the drug to the selected tissue at an instantaneous and absolute pressure that is in a tip (10) of the needle (30), and which varies due to the placement of the needle in the subject, having a minimum threshold absolute pressure of 200 to 500 psi (1379 to 3447 kPa) that is desired to administer the drug to intraligamentary tissue； a computer (102, 104, 106) that is connected to the drive unit (22) and that is programmed to drive the drive unit (22) to deliver the drug at least one flow rate； a pressure sensor (90) that is connected to the computer (102, 104, 106) to detect or calculate the instantaneous pressure based on real time； and a loudspeaker (23) that is connected to the computer (102, 104, 106), and characterized by being the computer (102, 104, 106) programmed to operate the loudspeaker (23) to provide a perceptible auditory ascending signal indicating when the instantaneous pressure is rising towards the minimum threshold pressure, being the ascending auditory signal to guide the movement of positioning the tip (10) of the needle (30) at least until the minimum threshold pressure has been achieved； the computer (102, 104, 106) is programmed to operate the loudspeaker (23) to provide a specific audible signal that indicates when the instantaneous pressure has reached the minimum threshold pressure； The computer (102, 104, 106) is also programmed to operate the loudspeaker (23) to provide a perceptible audible signal indicating whether the instantaneous pressure drops or fluctuates before reaching the
