Aspiration in dental local anaesthesia.

When injecting into a blood vessel (for example during intravenous sedation) it is essential to aspirate blood into the syringe prior to drug administration to ensure that the tip of the needle is lying within a vein. By the same token, when the injection is intended to be extravascular it would appear to be wise to ensure that no blood is aspirated into the syringe before drug delivery. This procedure is employed routinely by medical and nursing staff, but is not universally accepted by dentists prior to the administration of dental local anaesthetics.