I have had a few toothless cats now, and all have been able to eat biscuits - I spent months putting Snowy's biscuits through the food processor though, till she pinched some of Ginger's, then I realised she could eat them!! Ginger would sulk if he didn't get his supper biscuits (he was on a diet), and he could eat raw meat despite having no teeth, it just had to be small enough pieces for him.