[Fluffagrams]

I had to feed a diet entirely of soft foods to a hamster that had lost all his teeth due to a hereditary condition and he did well on it. His main diet consisted on mashed science selective pellets and then I'd give him things like baby food, porridge and mashed vegetables to give him some variety.

As others have said, keep an eye on his teeth to make sure that they don't get too long, particularly if he's not interested in chewing things any more.