ASPEN Dental Assisting Practice Exam

A local anesthetic vasoconstrictor is an additive that narrows blood vessels at the injection site. This vasoconstriction slows the uptake of the anesthetic into the bloodstream, so the nerve block lasts longer. It also constricts small vessels to reduce bleeding during the procedure, which helps the clinician see better and work more efficiently, while lowering the risk of systemic toxicity from the anesthetic. So the main reason it's used is to prolong the duration of anesthesia (and provide hemostasis) rather than to stiffen tissue, shorten duration, or have no effect.