Gap between gum and crown - is this normal? (Photos)

Yes, a crown is possible. When the remaining tooth structure is very little, we first build support using a dental post, and then place the crown on top of it.

By reading your description, I feel your issue is due to a high point in the crown. Excessive force on that point causes pain [during biting and heavy pressure]. So it's my advice, do not do anything with a lower crown. The issue is with the upper crown. It's my advice to take a second opinion.

After consulting with your dentist, you can have your front two crowns redone to make them longer. First, your crowns will be removed and then a new one will be made at the appropriate length.

Yes, a worn porcelain crown can sometimes be repaired, depending on the extent of the wear. If the crown is simply thinning but hasn't chipped or cracked, your dentist may use a composite resin material to reinforce the worn area. This can act as a temporary fix to prevent further wear. However,...

Food particles can get trapped between your crown and tooth, which may lead to decay, bad smell and pain. The crown should be removed, and if there is no decay in your tooth, a new crown that fits your tooth properly should be placed.