Botox injection in cheek resulted in crooked smile & asymmetry. What muscle was affected & when will I see improvement? (photo)

Unfortunately you are experiencing asymmetry. Over the next 3 months the Botox will begin to dissipate and your smile will go back to how it was originally.

It's tough to say exactly which muscles were affected as they do work as a group. It is possible that it is one of the zygomaticus muscles but could also be your levator anguli oris muscle. Most likely they are all somewhat affected. Botox usually wears off in 3-4 months but the best predictor is how long it has taken your previous Botox sessions to start to lose effect.

Thanks for your question and photos. Sorry to see you are having problems. I think you are correct that your zygomaticus muscle is blocked on the affected side. How long it lasts depends on how much Botox was injected into the muscle. If the Botox just spread to the area it should go away in a couple of weeks. If it was directly injected into the area it may take up to 3 months to resolve. I advise you go back to your practitioner and see if there are any options to help provide symmetry. 

It's unfortunate you had a bad experience with Botox injections. Assymetry that you are feeling is likely secondary to placement and dosage. I would followup with the injector and ask specifically about site of placement and the dosage. The effects should last 3 months depending on these factors. 

As discussed below, sometimes the results from these treatments is not ideal.  However, if you have not revisited your treating physician, I would go back and have them look.  Sometimes, you can improve the result by adding a little botox to the opposing muscle that is over acting and soften the result and improve the symmetry without have to just wait until the botox goes away.  A touch up treatment might be very helpful but check in with your doctor.Best of luck!