1. Sometimes when you receive an injection of novocain you may feel a spurt of adrenalin. Adrenalin is a hormone produced in the body and represents the body's natural “fight or flight” instinct ... it's what gave the caveman the impetus for self preservation. Fortunately for us, human beings rarely need this fight or flight instinct in the 21st century, but the human body doesn't know that. It still produces adrenalin when it perceives a threat; and while your dentist isn't a threat, having sharp objects stuck in your mouth is tantamount to a threat from your body's perspective. Hence, the adrenalin rush you get sometimes when you receive injections in the mouth. Part of the whole adrenalin experience is an increase in your heart rate and breathing ... and blood pressure.
2. If you are receiving medication for hypertension, some can either affect your sense of taste or cause your mouth to feel dry. If you are taking calcium channel blockers you may experience swelling or overgrowth of gum tissue, which can make chewing difficult. Overgrown gum tissue, in particular, can make it harder for you to keep your teeth clean around the gum line – requiring more frequent dental visits for cleaning and scaling. For serious gum overgrowth, the treatment is to surgically remove the excess gum tissue (a gingivectomy).
3. Let your dentist know what kind of hypertension medication you take so he/she will know what anesthetics not to use ... epinephrine is commonly added to local anesthetics. Epinephrine administered to hypertensive patients can sometimes result in a rapid increase in blood pressure, angina, heart attach or arrhythmias.