Introduction: The local anesthetic used in dental anesthesia is considered a painful procedure to the majority of patients, it is known that the intra- oral injection is one of the most common reasons why patients escape treatment and that is due to the acidic nature of the anesthetic agent which in turn may delay the onset of anesthesia.

Materials & Methods: The local anesthetic used for dental anesthesia is one of the most common reasons patients avoid undergoing certain treatments. This may be attributed to the acidic, irritating nature of the anesthetic which in turn may lead to a delayed onset of anesthesia.

In this retrospective study, 2% lidocaine with 1:80000 epinephrine buffered with 8.4% sodium bicarbonate (1:10) was evaluated for its effects on the onset time as well as pain response and the duration of anesthesia. 15 patients were injected with the anterior infra-orbital injection and IANB injection with and without buffering with sodium bicarbonate.

Results: Anesthesia onset time in sodium carbonate buffered anterior infra-orbital injection was decreased by 0.07 minutes compared with the conventional injection, and that was not statistically significant. And in the buffered IANB injection the onset of anesthesia decreased 0.87 minutes compared with the conventional injection, and that was statistically significant difference (p=0.048).

Anesthesia duration was also decreased by 8 minutes in the buffered infra-orbital injection compared with the conventional injection, and this was statistically significant difference (p=0.21) and in the buffered IANB injection the duration was also decreased by 19.6 minutes, and that was statistically significant difference. (P = 0.010)

The pain induced by the buffered infra-orbital injection was decreased statistically significant by 2 degrees (P = 0.001), and was decreased in the buffered IANB injection by 1 degree (P = 0.007).

Conclusion: Buffering the anesthetic solution with sodium bicarbonate may induce lesser pain during injection and may decrease the onset time, but may negatively affect the anesthesia duration.