I had veneers on front teeth permanently cemented. When I got home, I noticed the top of the veneers were not completely hidden below the gumline. A very tiny amount of natural teeth were still exposed. It took a keen eye to see it. I asked the dentist and he said not to have them below the gumline because it can cause gums to recede, bacteria and the way it is is easier to clean. I am concerned if not completely hidden it could cause decay? Is this acceptable or should veneers be below gums?