Pain on injection of prilocaine plain vs. lidocaine with epinephrine. A prospective double-blind study

Prilocaine has been described as causing less pain on injection than lidocaine with epinephrine, possibly because of the higher pH of the prilocaine anesthetic solution.

Three hundred ten consecutively seen patients in a general practice received a total of 334 maxillary buccal infiltration or inferior alveolar block injections, administered under clinical conditions by one of two dentists. Immediately afterward, patients rated the pain from each injection on a six-point scale. Twenty of these patients (in 21 separate appointments) received, and were asked to rate the pain associated with, a second injection of a contralateral tooth. The authors analyzed the pain response by operator, location of injection, patient's age, patient's sex and anesthetic.

The difference in perceived pain between lidocaine and prilocaine was not statistically significant. Regardless of the anesthetic used, the perceived pain was usually no more than mild. Of 334 injections, 292 (87 percent) were rated as causing either no pain or mild pain.

Under clinical conditions, there is no statistically significant difference between injection pain associated with prilocaine plain vs. that associated with lidocaine with 1:100,000 epinephrine.

Since there is no significant difference in associated pain on injection between prilocaine plain and lidocaine with 1:100,000 epinephrine, dentists may prefer lidocaine with epinephrine. Since there is less anesthetic in each cartridge of lidocaine, it may require the use of less anesthetic per patient, and the vasoconstrictor can prolong its duration.