Dental health is so critical for young children, and a great unit to teach towards the beginning of the school year in Pre-K and to re-visit in other ECE grades--especially before the school dental program begins. This blogger has some great related teaching tips, "Teaching Kids to Brush Their Teeth." Definitely check out!
Play dough for plaque...YUCK! On a side note, if you keep the play dough in the blocks overnight, it will harden. This could also be a GREAT lesson to teach how food left in between your teeth will turn into plaque and harden over time...which is why we need to floss on a DAILY basis!