Mushiba Tetsudou Episode 1

"Brush your teeth, or the Cavity Express will come get ya!" Dentist apprentice boy EGG, and his side-kick cavity pal C1 hops into the mechanical-biological-train "Cavity Express" to explore through cavity world to accomplish necessary training need to achieve yearning DOCTOR title! Toothbrush and Toothpaste as his arsenal, Boy Egg resist against bad-nasty-cavities to rush for the "End of the Journey Station"!!! Cavity Express is one of a kind, fantasy adventure animation! (Source: AniDB)