Effect of adding sodium bicarbonate 8.4% to local anesthesia on pain during upper canine infiltration

Background: Alkalization of local anesthetics may have an impact on alleviating the injection pain by buffering these solutions with sodium bicarbonate. The present study aimed to evaluate the pain during local anesthetic buccal infiltration for the maxillary canines after adding sodium bicarbonate 8.4% during local anesthesia. Materials and Methods: A buffered 2% lidocaine with 1:80,000 epinephrine and sodium bicarbonate 8.4% was used for one site, and an unbuffered 2% lidocaine with 1:80,000 epinephrine was used for the other site at the same appointment. Two groups of volunteers (15 male and 15 female) participated. Each participant received 0.6 mL of the anesthetic solution. Injection discomfort was assessed using a visual analog scale. Results: 73% and 93% of patients in group 1 experienced pain in sites A and B, respectively, during the injection, whereas 80% and 100% of patients in group 2 experienced pain in sites A and B, respectively, during the injection. Both groups showed a significant difference in pain scores between the two injected sites (P < 0.01). Conclusion: Upper canine infiltration anesthesia with buffered lidocaine and epinephrine with sodium bicarbonate has less pain during injection than when unbuffered lidocaine with epinephrine is used.