I don’t think its possible to clean their teeth without geeting scrached and bitten and getting them pretty traumatised too. The vets put them under to do it.
I think the best things are chicken wings or other boned meat to chew on and there is also special dry food designed to help keep their teeth clean. Not perfect but it should help.
Never, ever give a cat or a dog bones. Vets will tell you that they can too easily get pieces lodged in their intestines and die from infections.