I have always had my chin muscle lump up when I close my mouth since I was a child. I talked to the RN that does my Botox about it and she stated this was something Botox could relax and I was skeptical because it worked! The first time we only did four units, which wasn't enough so she added only two more and it was drastically improved. This is obviously a maintenance procedure about every three months. I get Botox in the eye areas as well but the overall cost for the chin is about 66$.