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A comparison of intraoral injection discomfort produced by plain and epinephrine-containing lidocaine local anesthetic solutions: a randomized, double-blind, split-mouth, volunteer investigation.

The authors report a clinical trial designed to compare the discomfort produced by plain and epinephrine-containing lidocaine solutions during local anesthesia in the maxilla. Twenty-four healthy volunteers were recruited; each received buccal and palatal infiltrations on each side of the maxilla in the premolar region. The solutions were 2% lidocaine and 2% lidocaine with 1:80,000 epinephrine. Allocation to side was randomized and operator and volunteer were blinded to the identity of the solutions. Volunteers recorded injection discomfort on a 100-mm visual analogue scale (VAS). Volunteers were included in the trial if a score of at least 30 mm was recorded for at least 1 of the matched pair of injections. Differences between treatments were measured using Student's paired t test. Twelve volunteers recorded a VAS score of at least 30 mm for 1 or both buccal injections, and 17 volunteers reached this score for palatal injections. Buccal injection pain was less when the plain solution was used (P = .04) and was not influenced by the order of the injection. Palatal injection discomfort did not differ between the solutions; however, the second palatal injection was more uncomfortable than the first palatal injection (P = .046). These results suggest that plain lidocaine produces less discomfort than lidocaine with epinephrine when administered into the maxillary premolar buccal sulcus in individuals who report moderate pain during this injection. Palatal injection discomfort does not differ between these solutions.