At three and five they still need your guidance. This is not a fun thing, but trust me - you want them to get god dentail hygience habits early. It will make all theidifference later when they have or don't have cavities, etc. ALso, their trips to the dentist will be better and later when it gets to braces, if needed, they really need to be familiart with taking good care of their teeth. Be diligent! It's worth it...