Common Problems Faced During Dental Anesthesia

I come across many patients who have some sort of complaints about their experience with dental anesthesia. I have tried to compile those in a way which can be helpful for you to refer to. The common problems related to dental anesthesia can be summarized as follows:

  1. The last time that you got an injection, you were numb for hours. Why? Is that normal?

Yes, though rare, it can happen. Getting an area numb (anesthetized) is a clinical skill that dentists or even anesthesiologists acquire over the years through clinical practice. The degree and duration of anesthesia depend on couple of factors:

a)The body metabolism. Anesthetic gets metabolized slowly in some individuals. On the other hand, if you drink a lot of coffee, the anesthesia will wear off rather quickly. The anesthetic can get metabolized very quickly also in patients with hyperthyroidism with higher BMR (Basal Metabolic Rate).

  1. b) Dentists have to learn the anatomical landmarks and based on that they administer the anesthetic. There is no set measurement for selecting the location for the injection.

For example, it is not that they go 10 mm behind the molars to give the injection, because it depends on your built. The measurements change depending on what size jaw bones you have. Also the individual variation of the position of the nerves play a role.

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Therefore, as a result, each time you can get varied response with the same kind of injection. At one time the desired numbness can be achieved which will wear off within a reasonable period of time. But the next time the dentist may end up placing it too close to the nerve. Because the injection is given by assessing the approximate location of the nerve, it is possible that in your case the dentist’s injection could have been very accurate and the anesthetic was placed in close proximity to the nerve producing profound and prolonged anesthesia.

  1. c) The type of anesthetic used. Articane HCl can produce a longer effect compared to that of Xylocaine HCl. You have to remember that the effect is temporary. Even if it takes a little longer than the previous visit, it is usually still within reasonable and normal limit.
  2. The last time the dentist could not get you numb and you felt the pain for a long time? Is that normal?

Yes, it is normal. It should not happen but it can happen. A dentist usually gives injection and allows a reasonable amount of time for the anesthetic to be effective. As explained before, the precise location for the injection can change depending on your built. Also the individual variation of the position of the nerves plays a role. In some cases, there can be additional or accessory nerves supplying the area. As a result with the same kind of injection each time you can get different responses. Because the injection is given by assessing the approximate location of the nerve, one time the dentist can get the desired numbness which wears off within a reasonable period of time. But the next time the same kind of injection may not effectively anesthetize all of the branches.


The best thing is to communicate with your dentist. As soon as you feel any discomfort, raise your hand. Do not jump. Remember, the dentist is working in your mouth with a sharp drill! A dentist who is compassionate about his/her patients will definitely stop and add more anesthetic to achieve the desired numbness.


It is not uncommon to get a burning sensation right when the anesthetic is administered. You may want to ask for the topical (surface) anesthetic gel a few minutes before the anesthetic is administered to make it little better.

  1. The injection that your dentist gives you in the roof of the mouth hurts. Why?

The tissue of the roof of the mouth (palate) is thin and firmly attached to the underlying bone. It has a rich nerve supply. So, when the anesthetic is delivered into that area, it stretches the tissue and you feel the intense pain. Unfortunately, very little can be done to reduce that discomfort. Sometimes though Articane HCl (Septocaine) can be used instead of Xylocaine. It penetrates the bone more eliminating the need for a palatal injection, provided the work that is needed is not too involved.

  1. When the dentist gave you an injection, you got a bruise in your face exactly in the area that corresponds to that tooth. Is that normal?

Yes. It can happen rarely and can still be normal. When an injection is given it pierces through the layers of muscles that are rich in blood supply. It always bleeds when an injection is given (usually you can taste the blood once the injection is given) but it may occasionally become visible externally if the bleeding takes place closer to the outer layer of the facial muscles. Also, it can get more noticeable, if you’re fair in complexion.

  1. When the dentist gave you an injection, your vision became blurred or you were seeing double. Is that normal? Did he do anything wrong?

No, the dentist did not do anything wrong. Again, it depends on the accuracy of the injection. The 5th Cranial Nerve or the Trigeminal Nerve splits into three divisions after emerging from the cranium (skull):

  1. a) The top branch (Ophthalmic Division) supplies the eyes among other things.
  2. b) The middle branch (Maxillary Division) supplies the top teeth and other tissues in the upper jaw (the Maxilla), and,
  3. c) The third branch (Mandibular Division) supplies the bottom teeth and other tissues in the lower jaw (Mandible).

If the dentist administers the anesthetic in the back where the main trunk splits into these three branches, you can feel the anesthetic effect also in your eye on the same side. It is normal.


For the same reason, you can feel referred pain in the top teeth due to a painful bottom tooth and vice versa.

  1. Your muscles hurt after the filling was done. Why?

When anesthetic is administered, the needle pierces through the muscle(s). You may not always feel it because it depends on which muscles are being subjected to trauma. If it is a muscle that is not often used, you may not feel unless you press on it. The discomfort usually is transient and goes away within days. But if it is a muscle that has to work hard when you chew food or smile, you may feel it more. If you’re a bruxer, you will keep on overworking your muscles, thereby delaying the healing. In that case, the discomfort can be there for a significant period of time.

  1. You fell sick when your dentist gave you the injection. It felt like your heart was ‘racing’. You were experiencing palpitation. Why?

The anesthetic most commonly used at the dentist’s office contains epinephrine among other active chemical agents. It is used to constrict the blood vessels to reduce hemorrhage locally and prolong the anesthesia. But at the same time, it can cause an increase in the heart rate. If you experience such problem inform the dentist right away. Your records will be updated to avoid such unpleasant reaction in the future. If you have had such experience before, don’t forget to include that in the health history when you first go to a dentist’s office. There are alternate anesthetics available, which do not contain epinephrine.

Research findings:

Oral submucosal injection of 40 micrograms of epinephrine accelerates the cardiac performance, with little change in blood pressure and heart rate.


You should also have a decent meal before getting the dental procedure done. However, you should not eat anything before a procedure that requires the administration of intravenous anesthetic (I/V sedation). For example, for the extraction of wisdom teeth.