Music is prevalent in the preschool classroom for a reason. Kids tend to enjoy it, and they learn well when themes are incorporated into song and dance, since they are kinesthetic learners. Make your hygiene songs by taking familiar tunes such as "Row, Row, Row Your Boat" and changing the lyrics to demonstrate a hygiene activity, such as Brush, Brush, Brush Your Hair." Remember to incorporate simple movement that demonstrates the action. If you don't want to write your own music, organizations such songsforteaching.com have various songs available for educational use.
Educational TV shows and storybooks teach lessons through dramatic action. Instead of telling your preschoolers why it's important to take a bath and floss, perform a skit that demonstrates it. You can bring in another adult or two for the "special performance." Remind the kids that there is some theater etiquette they should follow for the performance, such as being considerate and listening to the story. This way you also introduce the idea of arts appreciation. You might want to write an interactive skit where characters pause the action and ask students what they should do next. Or have students choose what a character should do, then have two different outcomes you can act out based on what students choose.
Use puppets to introduce proper hygiene in an engaging manner. Have a "make your own puppet" day activity, where kids make puppet "washing buddies" to help them wash their hands and face and brush their teeth when at home. Before students take their puppets home, you can have a demonstration day in your dramatic play area. Have kids show you how they brush their teeth, then ask the puppets how they brush their teeth. Continue with hand and face washing. Instead of each student having his or her own puppet, you can also have one puppet that asks students questions: "How do you floss your teeth? When do we need to cover our mouths?" Also, any skit or play can be adapted for puppets, which can sometimes engage preschoolers better than live action.