The word "hygiene" doesn't mean much to a small child. The concept of brushing teeth is foreign to kids-why would they want to put a funny-tasting stick in their mouth and move it  all around? If only children weren't susceptible to cavities. Below are some tips to teach kids how to take care of their teeth and yes, even have fun in the process.
Tricks For Getting Those Teeth Brushed- http://www.ivillage.com/tricks-getting-those-teeth-brushed/6-a-145193 
How does your little one do with teeth brushing? Is it a struggle in your house or does he/she do pretty well?