Dr gave numbing injection to my son, he's had ALOT of these with out issue before and is used to the brief burning sensation. This time he experienced significant pain, he was grasping armrests and visibly in pain. The dr dismissed his pain, basically said moms often think kids are braver than they are, it terrible bedside manner. My son said he felt the normal pinch and burn then intense tooth pain as well. Google says this can be from hitting a nerve directly or injecting anesthetic too fast.