You don’t say how old Susan is but it’s not uncommon for older cats to lose their teeth to the point where they have few, if any, left. Unlike people, fillings and crowns are not an option and once the teeth become damaged, or they get gum disease, extraction is the only choice. Also, unlike people, they do not complain if their teeth are causing a problem unless they actually prevent them eating.
I previously looked after a senior cat who had only a couple of teeth and she ate both wet and dry food without any problems. If Susan has been having discomfort she will feel much better now and once her gums have healed you’ll probably find nothing will have changed in terms of her appetite and what she likes to eat.