Do you really think it is necessary to swab before an injection? And how necessary is it to pull back? Dentists shoot drugs right into the masseter muscle in your jaw. It is one of the strongest most vascular muscles in the body. Yet they never swab the inside of your mouth with alcohol to sterilize it. They also never draw back to see if they are in a vein. The mouth is the dirtiest, most bacteria ridden part of your body inside or out (colon and rectum included). They just jab that needle into your jaw muscle and push the contents in. The arterial vasculature in your jaw has connections directly with the brain (external carotid, connecting to the periorbital arteries, connecting to internal cranial arteries, circle of willis).