Dental local anaesthetic solutions are usually contained in premade cartridges, designed for injection without any further mixing or addition. The only exception is 0.5% bupivacaine, with or without adrenaline. It is supplied in vials and so requires the use of a separate syringe. This type of anaesthetic is used by oral and maxillofacial surgeons for pain control after removal of impacted teeth. There has been at least one incident where a dentist used an injection of local anaesthetic from a cartridge and then separately injected sodium bicarbonate in an effort to counteract the acidic pH in an area of acute inflammation. This resulted in a permanent nerve injury with adverse medico-legal consequences for the dentist.
It is therefore recommended that dentists do not inject other solutions when using local anaesthetic cartridges.