Reverse block is far better prevented than managed. This means not diving when you are significantly congested, and, if you experience difficulties with equalization on the way down, perhaps not continuing the dive to much depth. In general, it will be easier for gas to ESCAPE from the airspaces than to enter them, and therefore equalizing on the way down should be more difficult than on the way up. This is because the escaping gas tends to dilate the passages through which it needs to pass, whereas, on the way down, the compression tends to collapse them. That's why reverse block is less common than simple difficulty with equalization.
Abdominal gas should not be a problem, as it isn't going to expand to any volume greater than its original volume on the surface, and it can distribute itself easily through the intestine.
Similarly with teeth -- Even if a tiny air bubble is left in a tooth after a procedure, you should have your pain on descent when it compresses, because it can't expand to a greater volume than it had when you began.
If you do experience a reverse block, you've already gotten good advance. Descend a little bit, work on jaw movement, swallowing, head positioning, and see if a slower ascent will allow it to work out. Since ascending is the one mandatory maneuver in diving, if you have a true block, you are eventually going to have to ascend and tolerate the pain and the damage that you are doing. Thus the recommendation to avoid situations where reverse block is likely.
