Does local anesthesia numb the bone also when they are doing oral surgery?

It should: Local anesthesia needs to numb the teeth and the bones because both have nerve endings and sensation which means both can experience pain. Extractions can cause much bone trauma and if it were not numb then it would hurt a lot. Many times the tooth to be removed is already non-vital and so it is primarily the bone being anesthitized anyway.

Technically no: It numbs the soft tissue around the bone. The inside of bone doesn't really have nerve endings for pain. It does, however, numb up the teeth also, which do have nerve endings.

Yes: Local anestheis provides anesthesia to the nerves that supply feeling to the bone. So, yes, the bone is "numb" and surgery can be completed without pain.

See below: Bones do not have any pain endings in them, so actually do not show pain. What does have nerve endings is the covering, periosteum, that surrounds the bone. This tissue is what is numbed by the dentist.