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Prognathism

One of the most common jaw conditions we treat, prognathism is highly correctable with outcomes that improve both function and facial balance.

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What Is Prognathism

Understanding Prognathism

Prognathism is characterized by a forward-positioned lower jaw often combined with an underdeveloped upper jaw, creating a pronounced imbalance in both bite and facial structure.

Patients with this pattern often experience functional limitations, including difficulty biting, chewing, and speaking, along with increased stress on the jaw joints. The imbalance between the upper and lower jaws can also affect overall facial harmony. Treatment focuses on repositioning one or both jaws to restore proper alignment, improve function, and create a more balanced and natural facial appearance.

Clinical presentation of prognathism, profile view with statistics.

Clinical Presentation

Clinical presentation of prognathism, frontal view.
Frontal View

Frontal Analysis

In prognathism, the lower jaw is positioned forward relative to the upper jaw, which can affect overall facial balance and symmetry. Some patients maintain symmetry, while others may show chin deviation or disproportion in the lower third.

Key Assessments:

Prominent lower jaw position
Chin projection or deviation
Dominance of the lower facial third
Dental midline discrepancy
Clinical presentation of prognathism, profile view.
Side View

Profile Analysis

From the side, prognathism is more clearly defined by the forward position of the lower jaw relative to the upper jaw and facial profile. This can create a concave profile with increased chin projection.

Key Assessments:

Forward-positioned lower jaw
Concave facial profile
Increased chin projection
Imbalance between upper and lower jaws
Clinical presentation of prognathism, occlusal view.
Bite View

Occlusal Relationship

Prognathism often affects how the upper and lower teeth come together, resulting in a bite relationship that reflects the underlying skeletal discrepancy, most commonly a Class III occlusion.

Key Assessments:

Class III occlusion pattern
Underbite (lower teeth ahead of upper)
Negative overjet relationship
Misalignment of dental arches

Prognathism

Common Functional Issues

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Eating

Difficulty biting into foods with the front teeth due to the lower jaw sitting forward, often leading to inefficient chewing and increased strain on the back teeth.

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Speech

Certain sounds, particularly “s” and “f,” may be distorted due to the altered relationship between the upper and lower front teeth.

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TMJ

An underbite can place uneven stress on the jaw joints, potentially causing discomfort, clicking, or fatigue with jaw movement.

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Mouth Breathing

Jaw position may contribute to altered tongue posture, which can encourage mouth breathing and affect oral health over time.

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Nasal Congestion

Nasal airflow may be less efficient due to imbalanced facial structure, sometimes contributing to snoring or mild airway resistance.

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Psychosocial Effects

A prominent lower jaw can affect facial balance, which may impact confidence, social interactions, or self-image.

Before & After Gallery

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Prognathism

Jaw Surgery Procedures

Orthognathic surgery corrects prognathia by setting back an overgrown lower jaw and repositioning the upper jaw to restore proper bite and, when necessary, repositioning the upper jaw to restore facial balance. Most commonly, double jaw surgery is performed, combining BSSO and Le Fort I osteotomy to create a more balanced, harmonious result.

BSSO

BSSO Result Illustration

BILATERAL SAGITTAL SPLIT OSTEOTOMY

A bilateral sagittal split osteotomy repositions the lower jaw backward, correcting the underbite and restoring proper occlusion.

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Le Fort I

Le Fort I Osteotomy Result Illustration

LEFORT I OSTEOTOMY

When maxillary deficiency contributes, the upper jaw may be advanced and subtly rotated to refine occlusion and facial balance.

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Double Jaw

Double Jaw Surgery Result Illustration

DOUBLE JAW SURGERY

Commonly, both jaws will be repositioned with controlled occlusal plane rotation to achieve stable alignment and optimal facial harmony.

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Life-Changing Benefits

Orthognathic surgery corrects an underbite by restoring proper jaw alignment, improving function, comfort, and long-term stability.

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Balanced bite and chewing
Reduced TMJ strain
Improved speech clarity
Harmonized facial profile
Improved breathing function
Increased self-confidence

Surgical Management of Prognathism

Lower Jaw

Bilateral sagittal split osteotomy corrects lower jaw protrusion by separating the mandible on both sides behind the last molar, allowing the tooth-bearing segment to be precisely set back into proper alignment. The repositioned jaw is secured with small titanium plates and screws, restoring a balanced bite, reducing chin projection, and improving chewing, speech, and lip closure. Each case is planned with advanced imaging and digital surgical simulation for a stable, predictable outcome.

Both Jaws

When prognathia is severe or accompanied by additional skeletal discrepancies, double jaw surgery is recommended. A bilateral sagittal split osteotomy is combined with a Le Fort I osteotomy, setting the lower jaw back while simultaneously repositioning the upper jaw to optimize the bite and facial profile. When indicated, a clockwise rotation of the maxilla and mandible further reduces chin projection and adjusts the occlusal plane. Both jaws are secured with small titanium plates and screws, improving chewing, speech, breathing, and facial balance. Each case is planned using advanced imaging and digital surgical simulation.

Presurgical Considerations

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Growth Completion

Key Assessment Points:

Serial X-rays
Underbite progression stopped
Growth spurt completed
Condylar size unchanged
Young girl in examination chair in doctor's office

Orthodontic Preparation

Key Assessment Points:

Incisor decompensation
Dental arches coordinated
Negative overjet accentuated
Transverse coordination optimized
Clinical jaw evaluation with a patient.

TMJ Documentation

Key Assessment Points:

TMJ function evaluation
Condylar position assessment
Joint symptoms documented
Asymmetric growth identified

Timeline for Prognathism

Month 0

Initial Consultation

Comprehensive history, clinical evaluation, 3D scans, X-rays, photographs, and impressions to assess jaw position and bite.

2–4 weeks after initial consultation

Treatment Planning Visit

Once your records are reviewed and the doctor has coordinated with your orthodontist, you’ll return either in person or via telemedicine to review your treatment plan, see prediction images, and go over the steps and timeline ahead.

6–12 months

Orthodontic Preparation (if necessary)

Braces or aligners gradually guide the teeth into proper positions to prepare the jaws for surgical
correction. In select cases, a surgery-first approach may be possible.

3-6 weeks prior to surgery

Final Surgical Planning

Virtual surgical planning determines precise bone movements for optimal symmetry, stability,
and facial balance.

2–4 weeks prior to surgery

Pre-Op Medical Clearance

Medical exams, lab testing, and final instructions ensure the body is fully prepared for surgery.

Typically a one-night hospital stay

Surgery Day

Corrective jaw surgery is performed to reposition the jaws, improve bite function, and enhance facial balance.

3–9 months after surgery

Post-Surgical Orthodontics

Final orthodontic treatment fine-tunes tooth position and bite, optimizing aesthetics, function, and long-term stability.

Experience Matters

“We personally plan your care, perform your surgery, and guide your recovery. No residents, no fellows, no handoffs.“

Choosing the right surgical team matters. You should feel informed, comfortable, and confident in every step of the process. At our practice, your care is provided by one of the most highly trained and experienced jaw surgery teams in the country.

When you come to our office, you meet directly with your surgeons. We are the ones who plan your treatment, perform your surgery, see you after surgery, and remain personally available to you throughout your recovery. Unlike larger institutions, your care is not delegated to residents, fellows, or doctors in training. Every critical aspect of your treatment is handled by your surgeons.

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Founding Members of the American Society of Orthognathic Surgery

What Our Patients Are Saying

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★★★★★

Dr Lee and the team at Northeast Facial are incredible. I was very nervous about my procedure but Dr Lee walked me through it step by step, never once making me feel rushed. Silvanna at the front desk went above and beyond to help me schedule an appointment that worked for me. I would highly recommend NEFOSS!

Stephanie Brown

★★★★★

“I had double jaw surgery done with Dr. Jacob in June 2021. I am extremely happy with my results. No more jaw pain and chewing problems. I also feel much more confident with my new smile. The surgery was definitely well worth it, thanks to Dr. Jacob and his team!”

Amelia Chen

★★★★★

“I would definitely recommend Dr. Jacob and his team at NEFOSS! Dr. Jacob and the team of doctors are very knowledgeable about all aspects of the TMJ process. They are such a nice group of doctors! The office staff is also very helpful and very friendly.”

Tiffany Puopolo

Frequently Asked Questions

Here are some common questions about prognathism and the surgical options available.

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