Disclosed are applicators and methods for injecting a liquid, such as anesthetic, into a patient with no or minimal pain. The applicator includes a coupling and a blade rotatably mounted on the coupling. The coupling is arranged to receive a cartridge in which a cannula is mounted such that the cannula extends through a proximal channel of the coupling and into a distal channel of the blade. The coupling is further arranged to secure the applicator to a source of liquid such that the liquid can be selectively introduced into and through the cannula into the tissue of the patient. The blade is thin enough for atraumatic insertion into a gingival sulcus of the patient.
