Background/objectives: This randomized controlled crossover clinical trial aimed to compare the anesthetic efficacy between intraosseous and buccal infiltration techniques as a primary anesthesia for mandibular first molars.

Materials and methods: Twenty adult subjects randomly received intraosseous injection of 1.7 ml 4% articaine with 1:100,000 epinephrine or buccal infiltration of 3.4 ml 4% articaine with 1:100,000 epinephrine at 2 separate appointments. The mandibular first molars were tested for anesthesia with an electric pulp tester at 3-minute cycles for 60 minutes after the injections. Pain ratings for each injection were recorded. The data were analyzed using the McNemar and Wilcoxon signed ranks tests.

Results: There was no significant difference (p = 0.250) in success rate between the intraosseous injections (95%) and buccal infiltrations (80%). However, the onset of pulpal anesthesia was significantly faster with the intraosseous injections (p = 0.004). No significant differences were found for injection or postinjection pain (p > 0.05).

Conclusion: The success rate of buccal infiltration using two cartridges of 4% articaine with 1:100,000 epinephrine is comparable to that of intraosseous injection using a single cartridge of 4% articaine with 1:100,000 epinephrine in asymptomatic mandibular first molars. Both techniques can be useful alternatives for inducing mandibular first molar anesthesia.