Crooked smile from fillers?

It most likely is something which was pre-existing but you just didn't notice. If that's not the case, then it could be from Botox/Dysport in this area. I haven't seen weakness of the marginal mandibular nerve from injections before either.

There may be several reasons for the crooked smile. First, it is possible that it existed before the injections and that it was just not noticed. Second, more filler could have been injected on one side versus the other. Third, filler could have been injected into a muscle. The good news is that if this is the case, it will dissolve. Botox and/or filler could be used likely. It is important to see a fellowship-trained expert! I wish you success!

Facial asymmetry is common and injecting fillers can make asymmetry appear more prominent in some cases after treatment. 

Your left lower lip labialis muscle is slightly weaker than your right side causing a very slight asymmetry.( it doesn’t pull your lower lip down as much as the opposite side)  This was likely pre existing issue and now you are hyper focusing on it since you had a facial treatment . Filler does not affect the marginal mandibular nerve that innervates this muscle. If a local anesthetic was used then it can temporarily affect that nerve but it wears off in a few hours . 

Hi,
Thank you for your question. Without seeing before the treatment photos, it is difficult to judge if fillers have caused or just emphasised slight asymmetry when you are smiling. You could check in with the medical practitioner who treated you. I think face to face consultation is the best option for a proper assessment of your situation.
Best Wishes from Melbourne, Australia

The asymmetry of the smile exist in every individual on this planet. If you carefully look at the photographs of yourself prior to the treatment you will see the same. In the majority of patients the right side of the mouth is a little lower than the left. Good luck from New York City

When we start injecting on our faces, we start to notice things that we didn't pay attention to before. Our faces, and our bodies for that matter, are asymmetrical, never the same on either side. It gets stronger over time from sleeping on one side of the face versus the other.  When you start using fillers, it becomes more apparent, You have to over fill one side to compensate the differences. You may need to go in for a touch up.