Hi there!
Kudos for wanting to keep your pups teeth healthy and strong! At 5 months they are shedding their puppy teeth and getting their adult teeth, so its not too big of a concern at the moment, but its never too early to get in the practice of good habits, and getting your pups used to the sensation of it.
You'll want to use a toothpaste especially for dogs, as the fluoride in human toothpaste is toxic to them. You can find it at your vet clinic or pet store, often in flavors such as peanut butter, malt, chicken, or mint. Check the label to be sure that its safe for young dogs, but I haven't heard of any that aren't.
Best of luck!



