Why would non-vital tooth hurt a lot during tooth extraction?

The most common reason to have difficulty numbing a tooth for an extraction is the presence of infection.Typically if the nerve block has been done successfully, there will not be discomfort. There are times however when there is accessory innervation that  needs to be numbed as well to achieve complete comfort. Additionally,  it is sometimes necessary for  Novacaine to be injected directly into the infected site  to make the extraction completely comfortable. It's possible, but not likely that the nerve beneath the tooth was directly affected and caused you to feel discomfort.I hope you found this information to be helpful,Dr. Champagne 

A non-vital tooth can still have a sensitive or inflamed periodontal ligament, which is the thin soft tissue that surrounds the roots and cushions the tooth. Furthermore, if you've had a history of abscess formation, that could also keep routine methods of local anesthesia administration from being as effective due to altered levels of PH. 

Hi,Any time teeth are endo treated (had root canal) and need extraction, they can be very hard to removed , due to they so dry and fragile they to break in the pieces during procedure of extraction, so your dentist might need to dig in deep in your gum/roots to remove all those pieces, that's what called surgical extraction might need sutures and stuff like that.Your question is that normal to have a pain, that depends, you mentioned your had an several abscesses in the past, in the case tooth has infection and abscess , no matter how much they numb you, you still can feel pain on your tooth even your tongue, lips  and the rest of your mouth is being numb, i think whatever your dentist recommends its best for you!, IV with OS or dentist with good surgical skills + IV,Good LuckGeorge Sahakyan DDS

In many instances as an Oral surgeon I have treated many teeth with root canal therapy that were failing for many reasons. To mention just a few, fracture of the tooth, recurring infection, and/ or loss of bone. Typically teeth that are treated with a root canal are very difficult to treat because the tooth itself at that point behaves like a piece of glass, and it continues to break as it is being removed, requiring the removal of bone or surgical sectioning (were you intentionally separate the tooth into segments) to facilitate its removal. This will definitively increase the degree of discomfort at the time of extraction or after. In cases like yours it's best to be sedated for the removal, since you are going to be more comfortable. Please visit your Oral Surgeon for evaluation and Good Luck!!

Hi, thank you for your question. I see your question pertains to pain during a tooth extraction. Even though the nerve of the tooth has been removed and a root canal has been performed, a broken down endondontically treated tooth can still have infection that is deepened in bone. When the infection around the tooth is severe, then the anesthetic sometimes do not work as well. It is not common to have this occur, and the alternative to have sedation as an adjudicative therapy to prevent further pain is recommended.

While there may not be a nerve inside a tooth while extracted, there are nerves AROUND the tooth, to the gums and ligament holding the tooth to the bone.  Pressure receptors are also unlikely to get profoundly numb, so there is still sensation during a tooth extraction.