Is Mandibular Molar Buccal Infiltration a Mental and Incisive Nerve Block? A Randomized Controlled Trial

Introduction: The aim of this study was to compare the efficacies of buccal local anesthetic infiltrations at various sites of the mandible in order to elucidate the mechanism of action of articaine mandibular infiltrations. Methods: After a power calculation and ethical approval, 22 volunteers received 1.8 mL 4% articaine hydrochloride with 1:100,000 adrenaline as a buccal infiltration at the canine, first, or second molar in a randomized, double-blind, crossover design. The injections at the canine and first molar were considered equidistant from the mental foramen. Responses of the first and second molars, first premolar, and lateral and central incisors were assessed using an electronic pulp tester over a 47-minute period. Volunteers were asked to rate the discomfort of each injection using a visual analog scale. Data were analyzed using repeated measures analysis, McNemar, and Mann-Whitney U testing. Results: Injections at the canine and first molar teeth produced anesthesia in all teeth tested in some volunteers. There was no significant difference between anesthetic success of the first premolar after infiltration at the canine or the first molar. Injection at the second molar failed to produce anesthesia of the incisor teeth. Anesthesia was significantly more likely after injections at an adjacent site. There was no difference in discomfort associated with injections at different sites of the mandible. Conclusions: Articaine first mandibular molar infiltrations achieve an effect via a combination of modified mental and incisive nerve block and local infiltration. Infiltration at the second molar produces anesthesia of both molar and premolar teeth, primarily via infiltration.