I really love the Petzlife oral gel. We've been using it and the vet said Sheba's teeth are fine except he mentioned that I may have slacked on my "strict" regimen.
Sheba won't let me use a toothbrush in her mouth and I don't know if just spraying it in her mouth will do well enough so I bought a rough towel...you know those ones that no matter how much fabric softener you use it won't get soft? I cleaned it with no soaps and then cut it into little 2" strips and I put the Oralgel on it and use my finger. The rough towel isn't as invasive as a toothbrush and lets me feel every tooth.
Good Luck!