齪

足 = 龰 + 口 : Mnemonic symbol: a football. Zapatista Zebra (zu) wants to pimp his football (足) in the space station's kitchen (Ø2). He thinks that a few more vitamins wouldn't hurt, so he extracts the vitamins from a mandarin (口) with a syringe (龰) to inject them into his football.

齿 = 止 + 凵 + 人 : Charlie Chaplin (ch) has an aching tooth (齿), and Neanderthal Man (人) is about to help him take it out using an electrical barrier (止) in the space station (Ø3). They attached the barrier to the tooth and as Neanderthal Man will plug it into the receptacle (凵), the barrier will pull out the tooth.