The teeth of the elephant are always difficult to see.  

Their teeth grow from back to front.  Six teeth in the top jaw and six in the bottom jaw.

Two teeth from each jaw are used at a time.  Once these are worn down, they move forward and fall out.  The root is absorbed in the jaw.   This is a painful process and might contribute to their mood.   In an attempt to ease the pain they chew branches and bite rocks.  The chewing is done in a backwards and forwards motion, not side to side like cows or humans.

In their lifetime they will lose 144 teeth.  Old elephants sometimes get an extra tooth, which can weigh up to 4 kilograms.