Hi Kardisa,
You description of "massive" cavity is troubling to me with respect to diving in a week or so.
Whenever a dentist has to work deep within a tooth there is the possibility of either exposing the nerve or decay so close to the nerve that it will begin to degenerate. In either case, root canal therapy is a real possibility and that possibility can become necessary immediately at the time of tooth preparation, within days of the preparation or some time in the future.
My own inclination... without being able to evaluate the condition of this tooth would be to recommend that you consider placing a reinforced zinc-oxide/eugenol temporary such as IRM base within the cavity preparation and a glass ionomer cement temporary over it.
The zinc oxide/eugenol is "sedative" to the nerve and the glass ionomer is hard enough to act as a long term temporary. This gives the tooth a chance to recover from the trauma of deep decay and preparation, allows for future evaluation without committing to any particular final restorative technique, allows for a root canal without destroying a permanent restoration and can last long enough to complete your dives. When done properly, there should be no trapped bubbles underneath.
If your dentist there doesn't have these materials, then a simple, unreinforced zinc oxide/eugenol cement can be used with good, old fashioned zinc phosphate cement mixed for use as a filling material. Most dentists have these materials.
If you decide to do a long term temporary filling as described, there is still the risk of needing a root canal and your symptoms could appear while diving. There is no way to avoid this fact.
As to what material to restore the tooth with, basically, fillings are meant for fixing "little" cavities. If the restoration needed to fix your "massive" cavity is larger than about 1/2 the width of the tooth or there is only a shell of a tooth left, then you should consider a gold or porcelain crown. Neither one of these can be done quickly... they require a preparation visit and a separate visit to cement the crown. Just because a filling can be placed into a tooth doesn't mean it is the appropriate material/technique to fix the tooth with.
Typically, fixing a tooth with a filling that really requires a crown will result in an early failure of either the filling material or the tooth. This may compromise the possibility of future restoration of that tooth and sometimes render the tooth non-restorable in the future (there is nothing left to restore once the filling or tooth fails).
The filling may seem quicker or less expensive but when you factor in the fact that you will have to address this same problem again in the future and at best, the next restoration will have to be a crown... if it is even possible... skip the intermediate steps and fix the tooth long term... one time.
Hope this helps.
Regards,
Laurence Stein, DDS
