Computerized local anesthetic delivery vs. traditional syringe technique. Subjective pain response.

A study was designed to determine if there are changes in the perception of pain when the flow rate and pressure of an injected anesthetic are precisely controlled. Fifty dentists were given contralateral palatal injections. One side was injected with the Wand injector, a new delivery system that uses a microprocessor and an electric motor to precisely regulate flow rate during administration. The control side was injected using a standard manual syringe, in which flow rate and pressure are operator-dependent and cannot be controlled accurately. The subjects used two subjective scales to describe their perceived pain experience. When their responses were analyzed the Wand injector was found to be two- to three-times less painful than the manual injection. The results were statistically significant (p < .001). The authors conclude that there is an optimal flow rate of anesthetic solution at which the perception of pain during an injection is minimized.