Masseter muscle hypertrophy can be caused by involuntary or habitual grinding of teeth, typically at night. This can cause the Masseter muscles to enlarge, giving a more square shaped face. Sometimes large Masseter muscles are genetic. Masseter muscle enlargement can be bilateral or unilateral giving the face an asymmetrical appearance.

Treatment with anti-wrinkle injections can help with Masseter muscle enlargement and also with the pain and discomfort associated with excessive jaw clenching.

Anti-wrinkle injections can be used to reduce the size of the Masseter muscles giving the face a pleasing oval shape with a gentle feminine curve instead of a square shape.

The effects of the injections will start to work in 4 to 7 days and the maximum effects will be seen at 6 to 8 weeks. Treatment will need to be maintained with a repeat treatment in 8 to 12 weeks. As the Masseter muscle atrophies maintenance treatments can be spaced out at greater intervals.