What Is a Protruding Lower Jaw (Mandibular Prognathism)?

A protruding lower jaw, also known as mandibular prognathism, occurs when the lower jaw extends forward beyond the upper jaw. This condition can cause a bulldog-like appearance, an underbite, and an overall unbalanced facial profile.

Common features of mandibular prognathism include:

• The lower teeth overlapping the upper teeth (underbite)
• A prominent, forward-projecting chin
• Difficulty closing the lips naturally
• Chewing and speech difficulties
• Jaw joint discomfort or TMJ problems
• A longer, more masculine lower face

Mild cases may improve with orthodontics, but for true skeletal discrepancies, surgery is required.

What Is Mandibular Setback Surgery?

Mandibular Setback Surgery is a jaw repositioning procedure designed to correct a protruding lower jaw and restore proper facial balance and bite alignment.

At Seoul Cheil Plastic Surgery, mandibular setback is performed using the Bilateral Sagittal Split Osteotomy (BSSO) technique, which involves:

• Making incisions inside the mouth (no visible scars)
• Cutting the lower jaw bone on both sides
• Repositioning the lower jaw backward to align with the upper jaw
• Fixing the bones in place with titanium plates and screws
• Surgery time: Approximately 2–3 hours under general anesthesia

Why Combine With Other Procedures?

For a balanced, harmonious result, mandibular setback is often combined with:

• Le Fort I osteotomy (upper jaw surgery) for vertical or horizontal adjustment
• Genioplasty to refine chin shape and projection
• Cheekbone reduction for overall facial slimming
• Rhinoplasty for profile balance
• Fat grafting to restore volume in key areas

This comprehensive approach ensures a natural, proportionate facial transformation.

Key Characteristics of Mandibular Prognathism

• Underbite: lower teeth overlap upper teeth
• Forward-projecting chin
• Difficulty closing lips naturally
• Long, masculine facial profile
• Jaw joint discomfort (TMJ)
• Speech difficulties or lisp
• A heavy, prominent lower face

Can Braces Alone Fix It?

In cases of true skeletal prognathism, orthodontics can align the teeth but cannot reposition the jawbone itself.
For moderate to severe cases, mandibular setback surgery is the only permanent solution to correct the bite and achieve a balanced, harmonious facial profile.

Mandibular Setback Surgery at Seoul Cheil Plastic Surgery

Seoul Cheil Plastic Surgery is a leader in jaw and facial bone contouring surgeries, offering:

• Over 20 years of expertise in orthognathic surgery
• Customized treatment plans for each patient’s unique facial structure
• Advanced surgical techniques for scar-free, precise results
• Comprehensive care, from consultation to post-op recovery



If you’re struggling with a protruding lower jaw or underbite, Mandibular Setback Surgery at Seoul Cheil Plastic Surgery can help you achieve a more balanced, confident smile—improving both function and aesthetics.

Book your consultation today and take the first step toward your new profile!