You do have to start cleaning a puppy's teeth from day one really. Just do it very gently so that they get used to you putting something into their mouth - either by using a finger brush (at first) and then moving on to a soft baby brush. Never ever use human toothpaste. Dogs can't spit and they could choke. They just swallow the proper dog toothpaste because it tastes of chicken or something. I clean my dogs teeth daily - its a bit of a chore - but pays real dividends. The dog I had before this one had severe dental problems from time to time, but then I had her as a three year old so she wasn't used to having her teeth cleaned. This one I had from 9 weeks and she allows me to do anything. Just as well, as she is a coated breed. The toothpaste I use and could highly recommend is called Virbac Enzymatic toothpaste. I don't think the vets sell it but I get it on line. If you want to watch a demo. of a dog having its teeth cleaned then there are a couple on YouTube which are really good. When you start to try to clean a dogs teeth, praise all the time and offer re-assuring words. Seems to work with my little dog.