Background: Intraosseous anesthesia (IO) allows the anesthetic solution to be injected directly into the cancellous bone. The anesthetic solution immediately reaches the periapical region, and thus the axonal area of the nerve, where it can temporarily disable the sodium pump. The effect is felt almost without any time delay, and only a small amount of anesthetic solution is required. Methods: This study aims to investigate the efficacy of IO using the AnestoⓇ device after infiltration anesthesia (IA) and/or inferior alveolar nerve block anesthesia (IANB) failed to work in symptomatic irreversible pulpitis (hot tooth). The 33 patients included in the study were treated additionally with 1.7 ml articaine hydrochloride with 1:100,000 epinephrine hydrochloride (UltracainⓇ D-S, Sanofi-Aventis, Frankfurt, Germany) IO. Results: The electrical pulp test showed that 95.76% of the volunteers reacted positively to the combination of IANB or IA with the IO. In women, the additive IO was effective at 97.22%. In men, the IO led to pain elimination in 94.00% of cases. The duration of the IO was less than a quarter of an hour (13.03 min). The IO worked longer in women than in men (13.61 min vs. 12.33 min). Overall, more than every third tooth that needed trepanation was located in the posterior area of the mandible (36.4%). Treatment of hot teeth in this area was associated with an increased pulse rate and increased residual pain. There was a moderate correlation (Spearman-Rho [IRI] = 0.280) between the Visual Analog Scale (VAS) score and bone density, and a significant correlation (IRI = 0.612) between subjective residual pain and bone width. The IO resulted in a moderate, transient increase in the pulse rate by approximately 20 bpm. This is similar to the temporary increase in heart rate after conventional anesthesia techniques in non-preloaded patients and can be considered clinically irrelevant. Conclusion IO with the AnestoⓇ device as an extension and deepening of local pain elimination is recommended for the treatment of hot teeth.