How come doctors don't knock you out for painfull medical tests and yet dentists can do it to pull a tooth?

My brother had to have small chips of bone taken out of his back for testing and they did with a large needle through his back that could chip off pieces. It took a long time to do and they would do it then check something then do it again. He said it was torture. Six years later he is still traumatized by it and says if they have to do it again he will kill himself before going through it again. He is not a kid he is 50 years old.
Answer:
Its not because of allergies. They have so many different anesthetics they could find one to knock a person out. Depending on the proceedure there are different reasons why they can't knock someone out. If they are taking blood tests they wont issue an anesthetic because it will be in the blood stream and can obscure the results of the blood sample.For brain or spinal tests they keep the patient awake to communicate with them throughout the proceedure. Since the brain and spinal column have important nerves the doctors need to know if they have touched something so they can correct it immediately. For example if you were having brain surgery your vision might go blurry for a second, in which case you would say so and the doctor would realize that was your optic nerves and act accordingly.

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Its because it might be harmful to the patient in case they are allergic to the medicines they give the patients.

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Something isn't right here, a needle to remove bone chips? Come on now. He may have had a bone marrow aspiration which is painful even though a local anesthetic is used. The primary reason for not "knocking you out" for testing is that the risk of anesthesia is too great for short term minor testing so that risk isn't taken. Meantime it is my experience that males are the total worst patients ever. They complain more, are more afraid of needles and are less cooperative, in general wimps and a royal pain to work with.

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Sedation requires additional education and training, not to mention a huge increase in insurance and office equipment. Typically, oral surgeons are trained and equipped to sedate patients. For a general dentist, it is not worth it.

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