These two newly created crowns have a small gap between them that causes food to be regularly stuck in the gap.

This is very common. And the cause is because the bone where you have both implants is flat. Therefore the gums are also flat in between. Reshaping of the gums before making the crowns and/or bulkier crowns around the gumline may help. Even then, it will be difficult to duplicate bone and gum contours in an area where you have lost teeth and bone for some time.

Crowns are created to mimic your original teeth as closely as possible unless discussed otherwise with your doctor. Like the rest of your teeth floss should be able to be placed in between. You should be happy with your treatment, if not please call you dentist back to discuss the issues.

A standard criteria is that teeth should be close enough so that dental floss goes through with some resistance, but can go down. If too tight, the floss won't go through or will break when doing this. If a space and floss goes through without any resistance, then they might be considered too far apart. The reason when that is not desirable is that food (especially meat) will push down between the teeth, irritating the gums and encouraging more plaque in that area. This is called "a food impaction site" and is not desirable. If this is causing you discomfort, then return to the dentist and have him evaluate it. Sometimes one of the implant crowns can be removed and sent back to the lab to made wider, closing up the space that you're uncomfortable with. If it cannot be removed by your dentist, then you have the choice of having it redone completely or living with the space. it just might mean that you have to floss and brush the area a bit more to keep it clean and more healthy.

Unfortunately, when you loose a tooth you also loose gum and bone and the loss of those structures creates a food trap. Without seeing you it is hard to determine how to fix the problem. Maybe remake a crown?