I visited 2 prosthodontists and sought treatment plans for dental implants. The 1st dentist suggested that the cat scan be done after pulling the teeth [all my remaining teeth are to be pulled and implants placed] - and he gave me a general estimate of the cost of the treatment. The 2nd dentist suggested I first get a catscan so that he can make a cost estimate. Does it make any difference if the catscan is before or after teeth are pulled ?
If you can tolerate having an interim full denture for use after extractions, the CT scan would be most valuable after the extractions are done and an ideal denture setup is placed. Regardless of cost estimates, this will allow you and your dentist to avoid surprises.
If more bone is lost at the time of extraction than was planned, a pre-extraction CT scan will be of less value. Further, if the teeth are removed first, an accurate surgical template can be used for your surgery. The key point is you being able to tolerate a removable denture while all the planning goes on.