A smile is the universal language of friendship, love, encouragement, happiness and kindness and losing the ability to smile properly makes this simple, but powerful, act of communication difficult. 

Smiling at people in the street, in shops, in bars, draws attention to the fact that your smile is different. Some people stare, some people ask what is wrong with your face, some people are just downright rude.

It becomes easier to try and hide the difference by not smiling at all or limiting it to very small, controlled, close lipped smiles, which in turn makes people thing you are miserable or unfriendly. 

Photos are the worst; constantly being told to smile, when that's the one thing you wish you could do but can't.