Size doesn't matter: needle gauge and injection pain

Many dentists prefer using smaller gauge (27- or 30-gauge) needles for anesthesia injection, believing that needles with a smaller diameter result in less injection pain than wider diameter needles. For this study, three dentists in a general practice administered 930 injections to 810 adult patients using 25- and 27-gauge needles for mandibular inferior alveolar block injections and 25-, 27-, and 30-gauge needles for maxillary buccal infiltration or palatal injections. Patients, who were blinded as to the needle gauge, were asked afterward to rate the injection pain on an 11-point scale (0-10). There was no statistically significant difference in perceived injection pain based on needle gauge when analyzed for injection location (mandibular, maxillary posterior, maxillary anterior, and palatal), injection side, patient gender, treating dentist, or overall. These results indicate that when it comes to injection pain and needle gauge, size does not matter.