I've not heard of this either but I surely hope that there's no basis for it. It's smart to have cats' teeth cleaned because otherwise all sorts of problems could result through neglect, such as gingivitis, which can be painful and some diseases, if left undiagnosed and untreated, can affect the heart and/or brain. I'd still take the risk and have my cats' teeth cleaned but talk to your vet about it if it's really a matter of concern to you. I'm going to ask mine now that you brought it up.