How To Fix An Underbite: Clinical Protocols, Treatment Timelines, And Corrective Options

Correcting an underbite, clinically classified as a Class III malocclusion, requires a systematic orthodontic or surgical approach tailored to whether the discrepancy is skeletal or dental in origin. Successful treatment relies on precise cephalometric analysis, age-appropriate growth modification, targeted dental movement using braces or clear aligners, or orthognathic jaw surgery to achieve a stable, functional occlusion. Typical clinical correction timelines range from 12 to 36 months depending on the patient's skeletal maturity and the severity of the jaw discrepancy.

Pre-Treatment Evaluation and Diagnostic Phase

Before initiating any underbite correction protocol, a comprehensive diagnostic workup is required to differentiate between a skeletal Class III malocclusion (where the lower jawbone physically outgrows the upper jawbone) and a dental Class III malocclusion (where the jaw alignment is normal, but the teeth are tipped in a way that creates an underbite). Failing to distinguish between these two etiologies will lead to treatment failure, unstable results, and potential temporomandibular joint dysfunction.

Diagnostic Requisites and Patient Classification Criteria

• Imaging & Imaging Software: High-resolution digital Panoramic X-rays, Lateral Cephalometric Radiographs (used to measure the ANB angle and Wits appraisal), and 3D Cone Beam Computed Tomography (CBCT) scans for precise airway and airway-space mapping.
• Intraoral Digital Scans: 3D STL models generated by intraoral scanners to map arch widths, tooth-size discrepancies (Bolton Analysis), and occlusal contact patterns.
• Skeletal Age Indicators: Hand-wrist radiographs or Cervical Vertebral Maturation (CVM) assessments on lateral cephalometric films to determine the remaining mandibular and maxillary growth potential.
• Skeletal Diagnosis Benchmarks: An ANB angle of less than 0 degrees (normal is 2 to 4 degrees) and a negative Wits appraisal indicating a true skeletal Class III relationship.
• Dental Diagnosis Benchmarks: Normal skeletal jaw base relationship (ANB > 0 degrees) with retroclined upper incisors and proclined lower incisors leading to an anterior crossbite.
• Budgetary and Commitment Thresholds: Average treatment costs range from $3,000 to $8,000 for standard orthodontic intervention, and up to $20,000 to $40,000 when combined with orthognathic surgery. Active patient compliance is required for a minimum of 12 to 24 months.

Clinical Correction Protocols for Skeletal and Dental Underbites

Step 1: Comprehensive Diagnostic Mapping and Cephalometric Analysis

The clinical team must map the patient’s facial skeleton to determine the exact degree of maxillary hypoplasia (underdeveloped upper jaw) and mandibular prognathism (overdeveloped lower jaw).

1. Obtain a lateral cephalometric radiograph and perform a tracing analysis. Pay close attention to the SNA angle (maxillary position relative to skull base), SNB angle (mandibular position relative to skull base), and the resulting ANB angle.
2. Measure the vertical dimension of the face. Patients with a high mandibular plane angle (long face) require different biomechanical forces than those with a low mandibular plane angle (short face).
3. Conduct a functional shift evaluation. Check if the patient can guide their jaw back into a centric relation where the incisors meet edge-to-edge. If they can, they possess a "pseudo-Class III" underbite, which has a highly favorable non-surgical prognosis.

Step 2: Interceptive Orthodontic Phase (Ages 5 to 10)

If the patient is a growing child with a diagnosed skeletal Class III deficiency, the clinician must intervene while the sutural growth of the maxilla is still active.

1. Palatal Expansion: Fit a Rapid Palatal Expander (RPE), such as a Hyrax or Haas appliance, to the maxillary first molars and premolars. Instruct the parent to turn the expansion screw 1 to 2 times daily (0.25mm per turn) for 2 to 3 weeks. This disrupts the midpalatal suture and prepares the maxilla for forward movement.
2. Reverse-Pull Face Mask Therapy: Deliver a Delaire or Petit-type face mask. Attach heavy orthopedic elastics from the intraoral hooks on the RPE to the external frame of the face mask. Adjust the vector of pull downward and forward at 15 to 30 degrees to the occlusal plane, delivering approximately 350 to 500 grams of force per side.
3. Compliance Tracking: Instruct the patient to wear the face mask for 12 to 14 hours per day, primarily during sleep, for a period of 6 to 12 months, or until 2 to 3 millimeters of positive overjet is successfully established.

Pro-Tip: Skeletal response to orthopedic forces drops off rapidly after age 9 or 10. Early intervention during early mixed dentition yields the highest skeletal-to-dental correction ratio, minimizing the need for invasive orthognathic surgery later in life.

Step 3: Orthodontic Decompensation and Alignment (All Ages)

For dental underbites, or as the preparatory phase for adult surgical patients, orthodontic forces are applied to align the dental arches.

1. Appliance Selection: Bond complete fixed orthodontic brackets (0.022-inch slot system preferred) or initiate customized clear aligner treatment with attachments designed for root torque control.
2. Leveling and Alignment: Progress systematically through dental archwires, starting with flexible 0.014-inch Nickel-Titanium (NiTi) wires, progressing to heavier rectangular wires like 0.019x0.025-inch NiTi, and finishing on rigid 0.019x0.025-inch Stainless Steel (SS) wires.
3. Class III Elastic Application: Introduce Class III orthodontic elastics. Hook the elastics from the lower anterior teeth (canines) to the upper posterior teeth (first or second molars). This applies a distalizing force on the mandibular arch and a mesializing force on the maxillary arch to tip the teeth into proper coordinate positions.

Warning: Excessive use of Class III elastics in patients with thin periodontal biotypes can cause lower anterior gingival recession and alveolar bone loss. Monitor the lower incisor root positions closely to prevent driving the roots through the outer cortical bone plate.

Step 4: Surgical Orthognathic Correction (Adults with Severe Skeletal Discrepancies)

If the patient is skeletally mature (generally over age 17 for females and 19 for males) and exhibits a moderate-to-severe skeletal Class III discrepancy, orthognathic jaw surgery is required.

1. Pre-Surgical Orthodontic Phase: Use braces to decompress the arches. This phase intentionally worsens the visual underbite temporary because it moves the teeth into their ideal positions relative to their respective jawbones, undoing any natural dental compensations.
2. Maxillary Advancement (Le Fort I Osteotomy): The oral and maxillofacial surgeon makes an incision above the upper teeth, cuts the maxillary bone, advances it forward by the planned measurement (often 4 to 8 millimeters), and secures it in place with rigid internal fixation titanium plates and screws.
3. Mandibular Setback (Bilateral Sagittal Split Osteotomy - BSSO): The surgeon splits the lower jaw bilaterally along the ramus, slides the lower dental arch backward into alignment with the newly positioned maxilla, and secures the bone segments with surgical screws.
4. Post-Surgical Finishing Phase: After 4 to 6 weeks of surgical healing, the orthodontist resumes light orthodontic treatment for 3 to 6 months to perform fine detailing of the occlusion using light elastics.

Step 5: Long-Term Retention and Occlusal Stability

Underbites have a notoriously high rate of relapse due to late mandibular growth spurts. Rigorous retention protocols are mandatory.

1. Upper Arch Retention: Deliver a Hawley retainer with an active labial bow to hold the expanded maxilla and advanced incisors in place.
2. Lower Arch Retention: Bond a fixed lingual retainer wire (custom-bent 3-to-3 wire, bonded to the lingual surfaces of the lower canines and incisors) to prevent the lower teeth from crowding or tipping forward.
3. Nighttime Wear Routine: Instruct the patient to wear their removable retainers full-time for the first 3 to 6 months post-treatment, transitioning to lifetime nighttime-only wear.

Comparison of Underbite Correction Modalities

Troubleshooting Common Treatment Complications and Relapse

Scenario 1: Re-emergence of Underbite (Relapse) During or After Retention

• Root Cause: Late mandibular growth in young adults (especially males in their early twenties) or poor compliance with prescribed retainer wear.
• Actionable Fix: Obtain a new lateral cephalometric radiograph to compare with post-treatment records to confirm if the change is skeletal or dental. If skeletal growth has resumed, orthodontic camouflage must be abandoned in favor of surgical evaluation once growth ceases. If dental relapse occurred due to retainer non-compliance, fabricate active clear aligners or a spring retainer to pull the upper incisors back over the lower arch.

Scenario 2: Development of TMJ Pain, Clicking, or Lock during Elastic Wear

• Root Cause: Heavy Class III elastics pulling the mandibular condyle out of its centric relation within the glenoid fossa, causing compression of the retrodiscal tissues.
• Actionable Fix: Suspend elastic wear immediately. Allow the temporomandibular joint to settle for 2 to 4 weeks. If symptoms persist, construct a flat-plane stabilizing splint for nighttime wear. Once asymptomatic, resume elastic therapy at a significantly lower force level (e.g., switching from 6 oz to 2 oz elastics) and gradually titrate up as tolerated.

Scenario 3: Lack of Orthopedic Movement with Face Mask Therapy

• Root Cause: Patient age is too advanced (anchorage units are calcifying) or the patient is not meeting the required 12-hour daily wear target.
• Actionable Fix: Assess skeletal age using a cervical vertebral maturation (CVM) scan. If the sutures are fused, discontinue face mask therapy to avoid tipping the upper teeth too far forward without moving the bone. If the patient is young but non-compliant, consider switching to an implant-supported skeletal anchorage system (BAMP - Bone Anchored Maxillary Protraction) which utilizes mini-plates secured directly to the bone, minimizing dependence on patient compliance.

Scenario 4: Extreme Lower Incisor Gingival Recession during Braces Treatment

• Root Cause: Over-retroclination of the lower incisors during compensation mechanics, pushing the dental roots through the thin lingual or labial cortical bone plate.
• Actionable Fix: Immediately cease distalizing or retroclining forces on the lower arch. Take a high-resolution CBCT scan to evaluate bone coverage around the compromised roots. If bone loss is severe, coordinate with a periodontist for a free gingival graft or connective tissue graft, and adjust the orthodontic treatment plan to accept a slightly larger overjet rather than sacrificing periodontal health.

Frequently Asked Questions

Can you fix an underbite without surgery as an adult?

Yes, mild to moderate dental underbites can be corrected in adults without surgery using braces, clear aligners, or Class III elastics to tip the teeth into proper alignment. However, severe skeletal underbites in mature adults cannot be corrected with orthodontics alone and require orthognathic surgery to achieve a healthy bite and correct the facial profile.

How long does it take to fix an underbite with braces?

Fixing an underbite with braces typically takes between 18 and 30 months. The exact duration depends on the severity of the bite discrepancy, whether tooth extractions are required to create space, and the patient's compliance with wearing prescribed orthodontic elastics.

At what age should underbite correction begin?

Skeletal underbite screening should begin by age 7. Interceptive orthopedic treatment (such as palatal expanders and face masks) is most effective between the ages of 5 and 10, when a child's jawbones are still growing and highly responsive to modification.

What happens if you leave an underbite untreated?

Leaving an underbite untreated can cause uneven tooth wear, a higher risk of tooth fractures, chronic jaw pain (TMJ dysfunction), difficulty chewing, speech impediments, and sleep apnea due to improper positioning of the tongue and airway.

Can clear aligners like Invisalign fix an underbite?

Clear aligners can correct mild to moderate dental underbites in both teens and adults. This is accomplished using specialized attachments and Class III elastics to shift the upper teeth forward and the lower teeth backward, though severe skeletal discrepancies still require comprehensive braces combined with surgery.

Consult a Board-Certified Orthodontist Today

Achieving a healthy, stable smile requires a highly customized clinical evaluation of your unique skeletal and dental structures. Schedule an appointment with a board-certified orthodontic specialist to receive your precise 3D diagnostic scan and map out your personalized path to a functional, confident bite.