Receding gums

I have receding gums on two of my teeth. I believe the term is "gingival cleft". Basically some of the gum has come away in an up-pointing triangle. It's happened on the third and fourth teeth out from the middle on the top.

Any idea what has caused this and how can I stop it and make the gum grow back?

Btw, I brush my teeth every day!

I have a dentist appointment for a month's time so am a little worried about whether my teeth are going to fall out in the meantime.