Oh mysh! That's horrible. This dentist's office should be reported. What might help to speed your healing buy an aloe vera plant leaf (I get them from my local super market about $5 and great for you skin) and take a q-tip or very clean fingers and rub the gooey substance in the leaf across your gums. Give it a few seconds to absorb into the gums and rinse with water, as it has a bitter taste. Aloe vera has incredible pain stopping and healing properties that's why it's used for burns. Next do the same with olive oil but you don't have to rinse after. Olive oil will coat your gums and the nutrients and vitamin e will also aid in speeding up the healing. This really does help! Get well soon!