Botox for TMJ - would exellis laser around my jawline be a good way to make ensure there is no sagging?

I am a 22 year old female looking to get Botox in my masseter for TMJ. A dentist in my area was recommended to me- is there any questions or things I should look out for to ensure that whoever is doing my botox is qualified? Also, I am concerned about skin sagging/ losing my somewhat sharp jawline- would exellis laser around my jawline be a good way to make ensure there is no sagging? Thank you!