First, let's state what might be obvious. If your wife's surgery had been routine, with normal healing, uncomplicated by infection or pain and she could hold a regulator without discomfort, then it would be hard to advise her to wait any longer than she has already waited -- i.e., six weeks. Normally, four to six weeks is sufficient time to allow for the risk of infection, provided there has been good healing and gum tissue has begun to fill in the empty socket. However, the nerve trauma may indicate that her case may be different. I had to consult with two of DAN's referral oral surgeons with experience in dive medicine for assistance on this issue.
Occasionally, proper healing is delayed, often in smokers or older people. In such cases, air can be forced into the subcutaneous tissues by the increased pressures in the mouth during a dive. This condition could further delay the healing process and can be uncomfortable.
Pain can impede the ability to hold the mouthpiece in place; a loosely held regulator during submersion can present a possible drowning hazard. One consultant also cautioned on returning too early to diving based on the softness of the lower jawbone (mandible) after a wisdom tooth extraction. The end of the mandible remains fragile until it's fully healed. Additionally, it is subject to fracturing when pressure is placed on the bone, such as when gripping a regulator in place.
Theoretically, if there is still some localized swelling (edema), offgassing of nitrogen from the area during decompression could be impaired. Although decompression illness in a small area of the jaw seems unlikely, we have insufficient data to be sure.
Finally, some types of pain medicine (those containing codeine, oxycodone or other narcotics) could promote nitrogen narcosis and impair performance and judgment underwater. Both consultants agreed that if you still have symptoms, diving is not a good idea.
Guidelines for diving after most dental surgery include waiting for:
1) A minimum of four to six weeks or until the tooth socket or oral tissue has sufficiently healed to minimize the risk of infection or further trauma;
2) Medication to control pain resulting from the surgery has been discontinued and there is no risk of drug interaction with nitrogen; and
3) The diver can hold the regulator mouthpiece without pain or discomfort for a period of time sufficient to perform a planned scuba dive.