chatdvm,
If properly done, (and I have no reason to doubt that), your porcelain jackets should cause no problems. If you are having a problem with them, then see your dentist...before you dive.
Porcelain jackets are simply caps made completely out of porcelain. There is no metal underneath. They are more brittle than porcelain fused to metal caps but can look much nicer. Your regulator usually rests between the bicuspid/molar teeth and as such, should not put any undue pressure on your jackets.
Unless there is some undetected pulpal pathology within the capped teeth, your dive will be uneventful...at least with respect to your teeth.
There are uncounted numbers of people diving with even more uncounted caps. It is extremely rare that diving causes a problem.
Relax, enjoy your diving.
Laurence Stein, DDS
:doctor: