What is the purpose of sodium bisulfite in dental cartridges?

Sodium bisulfite is included in dental cartridges primarily to prevent oxidation of the vasoconstrictor. In anesthetic solutions that contain vasoconstrictors, these additives are sensitive to oxidation, which can reduce their efficacy. When sodium bisulfite is present, it acts as a preservative that stabilizes the vasoconstrictor, thereby ensuring that it maintains its potency until the solution is used. This is crucial because the effectiveness of local anesthesia can be significantly impacted if the vasoconstrictor is degraded, leading to inadequate anesthesia and potentially complicating procedures. The presence of sodium bisulfite helps ensure that the vasoconstrictor can perform its role effectively, which includes prolonging the duration of anesthesia and minimizing bleeding in the surgical area.