You can go as basic as using a piece of gauze to clean the teeth and stimulate the gums to buying any appropriate sized brush from most pet stores. My veterinarian recommends just using gauze but I use a basic small brush from my local pet store. The important thing is to be brushing and stimulating the gums every day to keep plaque down.
I use an enzymatic toothpaste like Virbac because the enzymes will continue to aid in breaking tartar down after brushing is done.
It's a good idea to wait 30 minutes after eating to brush their teeth and hold off treats/food for at least 30 mins after brushing too. You can let him play with his toys but definitely hold off on any treats for a bit after brushing. If you're worried about the bacteria you can always look for natural ways to clean the toys. I use a vinegar solution on mine if I need to clean them but most toys that cannot be cleaned don't last long enough for me to need to worry.
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