Bleach or alcohol. You can take a cup and do 1/3 rd household bleach and rest water, keep the tooth in it for 5 to 10 min. Discard the diluted bleach and wash the tooth with water. Please keep the cup or jar of diluted bleach far far away from reach of children during that 5 to 10 min of disinfecting the tooth! Can do the same with over the counter alcohol.
See below. You could boil them or clean with a bleach solution. However, there is no reason to do so.
10% bleach. Most people just rinse them off with a little soap and water. If you truly want to sterilize the tooth though, let it soak in a 10% bleach solution for 24 hrs. Unless your baby has some deadly disease that nobody else in the family has though, (highly unlikely) this is probably overkill.