To Blargh, Gasman and Starfish,
A properly integrated (healed) implant will have no air spaces in the bone. There are places within the implant body which can have air spaces but they are not in contact with bone. These spaces are the threaded areas used for the screw that secures the outer prosthesis to the underlying implant. If the screw becomes even slightly loose, food, germs, and other nasty things will accumulate there. Drainage is possible from such a space because it is usually just under the edge of the gum and all this crud can cause gingival inflammation and drainage.
You didn't mention if the implant was upper or lower. An upper implant can impinge on the maxillary sinus. In rare cases, sinus infections can drain through the interface between the bone and the implant. Usually, this will be picked up by the surgeon and proper advise for the future of the implant will be given. If the implant was in the mandible (lower jaw) there is no source of an air space associated with a properly healed implant.
Bone healing takes up to a year to mature.
You also didn't mention if a bone graft was done to augment the bone surrounding the implant. The graft material, especially if it is synthetic may sometimes work it way to the surface and create drainage. This should be checked by the surgeon.
The bite on an implant tooth should be a single point contact in maximum bite and every effort should be made to keep the bite as lite as possible. An implant is directly connected to the bone and not capable of moving. Real teeth can move slightly to absorb the stresses of chewing. If the implant bite is slightly off, there could be pain.
To Starfish, if your bridge is cold sensitive and floss sensitive, don't assume that the bridge shrinks and causes the pain. If it did, the porcelain would break off. You should be concerned about the possiblity of marginal leakage and recurrent decay, a nerve going bad under one or more of the supporting teeth or a loose bridge. Sensitivity immediately after placing a fixed bridge may be normal but it should improve. If it continues, there could be an undetected problem. Your dentist should check to see if the bridge is loose, decay exists under one of the supports (many people believe that a tooth with a cap or a bridge is protected from decay--NOT TRUE!), at the very least, try to identify the offending tooth and keep an eye on it.
One last tidbit. Some dentists use nonprescious metals for crowns. They contain nickel. Many women (15%-25%) are allergic to the metal. Men have less allergy because they tend to wear less jewelry. If you cannot wear stainless steel pierced earing studs, or you must wear earings made of gold studs, you could be allergic to nickel. If used in a crown on top of a tooth or an implant, the gum can get really red, look infected. Sometimes the gum is almost reddish blue it is so inflammed.
I don't know what is wrong with the implant but drainage is not a good sign and there is no place to trap air that would cause barotraumatic pain in a properly healed one. Crud in the screw space could cause drainage and gum pain but it would persist after the dive and it might be there before the dive. There are a lot of things that have to be ruled out--including the bite but the drainage comment really sticks out.
Finding a dentist who understands diving might not be a real necessity. Finding the root of the implant problem is.
Regards,
Laurence Stein, DDS
Steindiver@aol.com